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1985
REFINEMENT OF TECHNOLOGY FOR EXTRACTION AND UTILIZATION OF APRICOT KERNEL OIL AND
PRESS CAKE
ThesisThesisThesisThesis
by
HIMANSHU SHARMA
Submitted in partial fulfilment of the requirements for the degree of
MASTER OF SCIENCE
FOOD TECHNOLOGY
COLLEGE OF HORTICULTURE
Dr Yashwant Singh Parmar University of Horticulture and Forestry, Nauni,
Solan - 173 230 (H.P.), INDIA 2013
Dr. P.C. Sharma Depar tment of Food science and Technology Sr. Horticultural Technologist Dr. Y. S. Par mar University of Horticulture
and Forestry, Nauni-Solan--173 230 (H.P. )
CERTIFICATE – I This is to certify that the thesis entitled, “Refinement of technology for
extraction and utilization of apricot kernel oil an d press cake” submitted in
partial fulfilment of the requirements for the award of degree of
MASTER OF SCIENCE FOOD TECHNOLOGY to Dr Y S Parmar University of
Horticulture and Forestry, Nauni, Solan (H.P.) is a record of bonafide research work
carried out by Mr. Himanshu Sharma (H-2010-22-M) under my guidance and
supervision. No part of this thesis has been submitted for any other degree or
diploma.
The assistance and help received during the course of investigations has
been fully acknowledged.
______________________ Place: Nauni, Solan Dr. P.C. Sharma Date: (Chair man, Advisory Committee)
CERTIFICATE – II This is to certify that the thesis entitled, “Refinement of technology for
extraction and utilization of apricot kernel oil an d press cake” submitted by Mr.
Himanshu Sharma to Dr. Y S Parmar UHF, Nauni, Solan (H.P.) in partial fulfilment
of the requirements for the award of degree of Master of Science Food
Technology has been approved by the Student’s Advisory Committee after an oral
examination of the same in collaboration with the internal examiner.
_________________________ ___________________ Dr. P.C. Sharma Internal Examiner (Chairman, Advisory Committee) Dr. Girish Shar ma
Members, Advisory Committee
____________________ __________________ Dr. (Mrs.) Devina Vaidya Dr. (Mrs.) Manisha Kaushal ______________________ Dr. (Mrs.) Monika Sharma
_______________________________ Dean’s Nominee
Dr. S. K. Patiyal
________________________ Professor and Head
Department of Food science and Technology
________________________
Dean College of Horticulture
CERTIFICATE – III
This is to certify that all the mistakes and errors pointed out by the
external examiner have been incorporated in the thesis entitled, “Refinement
of technology for extraction and utilization of apr icot kernel oil and
press cake” submitted by Mr. Himanshu Sharma (H-2010-22-M) to Dr.
Yashwant Singh Parmar University of Horticulture and Forestry, Nauni, Solan
(Himachal Pradesh) in partial fulfilment of the requirements for the award of
degree of MASTER OF SCIENCE in Food Technology.
__________________________________________
(Dr. P.C. Sharma) Sr. Horticultural Technologist
Chairman, Advisory Committee
__________________________________________
Dr. V.K. Joshi (Professor & Head)
Department of Food Science Technology Dr. Y. S. Parmar UHF, Nauni, Solan – 173 230 (HP)
ACKNOWLEDGEMENT
Every result arrived at is a modest beginning for a higher goal. My work in the
same spirit is just a step in the ladder. It is a drop of ocean. No work can be turned as
a one man show. It needs the close cooperation of friends, colleagues and the guidance
of experts in the field to achieve something worthwhile and substantial.
Sheer words cannot help articulate my most candid gratitude to the chairperson
of my advisory committee, Dr. P.C. Sharma, whose superb guidance, critical analysis,
constructive criticism, constant enforcement & unparallel execution of the essential
requisites during the entire course are beyond the reach of my formal words. I would
remember him more as a guardian than as a guide.
I emphatically extend my heartfelt thanks to the worthy members of my
advisory committee Dr. (Mrs.) Devina Vaidya, Dr. (Mrs.) Manisha Kaushal and Dr. (Mrs.)
Monika Sharma for their constant help, encouragement and valuable suggestions during
the investigation and manuscript preparations.
I would like to avail this chance to extend my thanks to Dr. V.K. Joshi (Professor
and Head, Department of Food Science and Technology) for their wise guidance and
suggestions.
Nostalgia prevails over me as I recall the amiable, ineffable, unforgettable
company and youthful insouciance of my friends without which life would have been
insipid and devoid of hue.
Special thanks are due to my seniors Reena, Vikas Chopra, Vinay Chandel, Manish
Thakur and Prem Prakash, the faculty, office, field and Laboratory staff are thankfully
acknowledged.
I also extend my sincere thanks to the Keerti kaundal, kajal khattri and Sita
sharma for their help & cooperation.
Above all, the utilitarian asset, of course, my adorable and esteemed Dadiji,
Papa, Mumma, Chachaji, my elder brother and bhabhiji, didi and jiju, deserve my
ravishing thanks, whose benignant advice and abiding hallowing, always stood by me in
tough times.
Last but not the least; I thank almighty God for everything, who continues to
look after despite our flaws and limitations.
Needless to say, errors and omissions are mine.
Date: 06-01-2013 Place: Nauni, Solan (Himanshu Sharma)
CONTENTS
Chapter Title Page (s)
1 INTRODUCTION 1-3
2 REVIEW OF LITERATURE 4-17
3 MATERIALS AND METHODS 18-28
4 EXPERIMENTAL RESULTS 29-45
5 DISCUSSION 46-57
6 SUMMARY AND CONCLUSION 58-61
7 REFERENCES 62-67
• ABSTRACT 68
• APPENDICES I-IV
LIST OF TABLES
Table Title Page No.
1 Soaking treatments of apricot stones and kernels to optimize kernel separation efficiency in mechanical separator
20
2 Detail of pretreatments of apricot kernels prior to extraction of oil
20
3 Detail of pretreatments of press cake followed by extraction of volatile oil
22
4.1 Effect of soaking treatments of decorticated apricot stone fractions on the angle of static friction (θ) of stones, kernels, shells and mixture of shells and kernels on different rolling surfaces
30
4.2 Effect of soaking treatments on the moisture and size parameters of apricot stones and kernels.
31
4.3 Effect of soaking treatments on the efficiency of kernel separation in mechanical separator
33
4.4 Effect of soaking, steaming and oil extraction methods on the yield and quality of apricot oil and press cake
36
4.5 Effect of soaking, steaming and oil extraction methods from apricot kernels on the Tintometer colour units of extracted oil
38
4.6 Effect of soaking, steaming and oil extraction methods from apricot kernels on the quality characteristics of extracted oil
39
4.7 Effect of soaking, steaming and oil extraction methods from apricot kernels on the Fatty acid composition (% w/w) of extracted oil
42
4.8 Standardization of method for extraction of hydro-distillate/volatile oil from apricot kernel press cake
43
4.9 Effect of different concentrations (%) of apricot press cake volatile oil on the mycelial growth rate of some plant pathogenic fungi
44
4.10 Inhibitory effect of apricot press cake volatile oil against some plant pathogenic fungi
45
LIST OF PLATES
Plate Title Between
Pages
1. Mechanical separator for separation of apricot kernels from decorticated stone mass
32-33
2. Apricot kernel oil extracted through Table oil expeller 36-37
3. Volatile oil from apricot kernel press cake 44-45
4. Mycelial growth inhibition caused by volatile oil from apricot kernel press cake after 7 days of incubation in different fungi
44-45
LIST OF FIGURES
Figure Title Between
Pages
1. Effect of soaking pre-treatment on angle of static friction (θ) of apricot stones, kernels, shells and shells+kernels on different surfaces
30-31
2. Effect of soaking pre-treatment on sphericity (%) of apricot kernels
30-31
3. Effect of pre-treatment on separation efficiency of apricot kernels in mechanical separator 34-35
4. Effect of pre-treatment of apricot kernels on yield (%) of extracted oil for table oil expeller 34-35
5. Effect of pre-treatment of apricot kernels on the HCN content (mg/100g) of extracted oil and press cake 40-41
6. Effect of pre-treatment of apricot kernels on the tocopherol content (µg/g) of extracted oil 40-41
7. Benzaldehyde content of volatile oil from apricot kernel press cake 44-45
CHAPTER–1
INTRODUCTION
The apricot (Prunus armeniaca L.) a member of Rosaceae family is one
of the most important temperate fruit grown in India. Among stone fruits, apricot
ranks next only to plum and peach. Apricot has wide climatic adaptability and
grows well between elevations of 900-2000 meter above mean sea level. In India
it is grown in the states of Himachal Pradesh, Jammu & Kashmir and Uttrakhand.
Total production of apricot in the country has reached to be 16,739 tonnes from
an area of 4,886 ha during the year 2011 (FAO, 2011).
In Himachal Pradesh, it occupies an area of 3483 hectare with annual
production of 2,447 m tons (Anonymous, 2012). Beside cultivated apricots, a
substantial quantity of wild apricots commonly known as Chulli, Chullu is also
found growing in various parts of HP, Uttarakhand and J&K.
Both cultivated and wild apricots are used in processing for conversion
into different value added products. During these processing operations, a large
quantity of stones/pits are left after utilization of edible portion are thrown as
waste, the kernel of which can serve as good source of oil. Locally, small
quantity of stones is used for extraction of oil, but the method of oil extraction is
quite unhygienic and result in low oil yield with poor quality. The developed
method of apricot oil extraction consisting of mechanical decortication of stones,
separation of kernels by dipping in salt solution, extraction of oil in table oil
expeller, filtration in oil filter press followed by packaging ( Sharma et al., 2005)
further needs refinement to improve the yield and quality of oil.
After decortication of stones, the kernels are generally separated by
dipping the crushed shell as well as kernels in the salt solution, which helps in
separation of kernels (Sharma et al., 2005). However, the adoption of method is
limited due to apprehension of presence of salt in the kernels and oil. The
development of mechanical separator is required for separation of kernels. The
mechanical separator works on the principle of rolling of spherical kernels on the
moving belt. The roundness of kernel is used to allow them to roll on the belt.
2
Soaking of stones or kernels result in their swelling (Fathollahzadeh et al., 2008).
This property can be utilized for making the kernel spherical to allow them to roll
on the upward moving belt, to help in their separation. However, soaking also
affects the oil yield and quality which needs detailed scientific investigations.
Physical properties of apricot kernel are necessary for the design of
equipments of processing, transportation, sorting, kernel separation and oil
extraction. Fathollahzadeh et al. (2008) described the physical properties of
apricot kernels as a function of moisture content. The physical parameter like
length, breadth, thickness, geometric mean diameter and surface area of stones as
well as kernels are known to affect quality as well as yield of the oil. Thus
optimization of this parameter is also helpful in designing the equipment for
kernel separation.
The extraction of oil from apricot kernels is dependent upon many factors
such as moisture content in the kernels, extent of release of oil from the kernels,
temperature used during oil extraction and pressure used in the expeller for oil
extraction, etc. Most of the factors also affect the quality and quantity of the oil.
Thus, there is a need to optimize the method for extraction of oil from apricot
kernels.
The press cake left after extraction of oil from bitter kernels of almond is
the source of volatile oil commercially known as bitter almond volatile oil. The
volatile oil does not exist as such in the kernels but in the form of cyanogenic
glucoside-amygdalin (C20 H27 NO11- mandelo nitrile genitobioside). In the
presence of inherent β-glucosidase (emulsin) enzyme, the amygdalin is
hydrolyzed in to benzaldehyde, HCN and glucose. Upon completion of the
hydrolysis, the material is steam distilled to collect the volatile portion of the
benzaldehyde. The press cake of bitter almond yields about 1 per cent volatile oil
corresponding to about 0.5 per cent from kernels. The residue, which is free from
HCN, can be used as an animal feed or for isolation of proteins. Generally, two
types of kernels i.e. sweet and bitter are found in both cultivated and wild
apricots. Volatile oil, which is identical with bitter almond oil, can be distilled
from bitter apricot kernel and press cake which is cheaper and give higher yield
(0.8-1.6%) than that of bitter almond kernels. The press cake from bitter apricot
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kernels is known to yield 1.6 per cent volatile oil. Thus, after extraction of oil
from the kernel, the press cake can be used for extraction of volatile oil after
steam distillation. After removing the HCN from the volatile oil, the
benzaldehyde, which is the chief constituent in the volatile oil, can be used as a
flavourant in food industry as well as in cosmetic industry. Further the
benzaldehyde and HCN are reported to possess good antimicrobial properties
which can be used against many bacterial and fungal diseases. The available
information on development of Mechanical kernel separator, improved oil
extraction method and commercial method for extraction and utilization of
volatile oil from left over press cake is scanty. Thus, the present study has been
undertaken to meet the following broad objectives:
� To optimize method for separation of kernels from decorticated apricot
stones mass.
� To standardize pre-treatment for improving yield and quality of apricot
oil.
� To develop method for extraction and utilization of volatile oil from
apricot kernel press cake.
CHAPTER–2
REVIEW OF LITERATURE
In Himachal Pradesh large area is under wild apricot plantations, whose
fruits are mainly utilized for making country liquor while stones are used for oil
extraction purposes. Owing to its perishable nature, majority of apricot fruits are
utilized as fresh as well as in drying and processing for preparation of different
value added products. After processing, large quantity of stones/pits are left and
are thrown as a waste which can be utilized for oil extraction and preparation of
different value added products. Except for few solitary reports on chemical
characteristics of oil from apricot fruit kernels and utilization of oil for value
addition, no systematic work has been reported in the literature. Besides, very
little work has been conducted on utilization of press cake left after kernel oil
extraction in preparation of value added products. Nevertheless the work
conducted on different aspects of extraction and utilization of kernel oil and press
cake for preparation of different products has been reviewed as under.
According to Dwivedi and Dwivedi (2007) chulli fruits are sour in taste
and cannot be used for table purpose. Also, the kernels, which is obtained from
the wild apricot, is bitter and sour and cannot be consumed as dry fruit. For this
reason, it is used primarily for oil extraction and left over meal is used as animal
feed after it is boiled. The apricot oil has immense medicinal properties and is
used for joint pain etc. Besides, the oil is used for cooking after it has been boiled
properly and also for cosmetic use (Parmar and Sharma, 1992).
2.1 Composition of fruits
Physical character of apricot fruits grown in different area are reported to
vary. According to Sharma (1994) fruit weight of apricot grown in Kinnaur
district of Himachal Pradesh ranged from 4.0 to 29.3 g with fruit weight and
diameter varying between 1.9 to 3.6 cm. Average weight of stones from different
fruits in Kinnaur in Himachal Pradesh varied between 0.5 to 2.9 g while other
parameter were recorded as flesh stone ratio of 2.7 to 15.5 and kernel weight of
0.2 to 0.7 g.
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Sharma et al. (2005) reported that apricot grown in Solan has stone
weight ranging between 1.106 to 1.150 g with shell thickness of 1.19 to 2.01 mm.
while the pulp/stone ratio of 9.9:1.0 to 13.3:1.0 and kernel weight of 0.35 to 0.42
g. While most of the fruits grown in kumaon region of Uttarakhand were found to
be larger in size with size parameter varying between 3.13 to 5.55 cm in length
and 3.16 to 4.87 cm diameter (Rodriquez et al. 1971). The average share of
kernel in the total weight of the fruit is 26 per cent while that of endocarp is 74
per cent. Based on the chemical composition and percentage of kernel, apricot is
considered as similar to almond.
2.2 Stones/pits
The pits/stones of wild apricot fruits are considered as waste and are
thrown away by the farmers. Mean fruit weight of bitter and sweet kernelled
apricots ranged between 8.0 to 15.1 g and 16.0 to 18.3 g with the stone recovery
of 12.7 to 22.2 per cent and 11.7 to 13.3 per cent respectively (Gupta and
Sharma, 2009).
Sharma et al. (2005) reported that the stone weight in apricot however
ranged between 1.16 g (chulli) to 1.50 g (Newcastle), whereas the thickness of
shell was recorded to be 1.19 mm. Gupta and Sharma (2009) reported stone
weight in wild apricot ranged from 1.78 to 1.92 g while, stone weight of sweet
kernelled stones were ranging from 1.88 to 2.43 g. However, the percentage of
kernel and pits in various stone fruits is also known to vary with the variety, agro-
climatic condition, location etc.
2.3 Kernels
Hallabo et al. (1985) found that the apricot seeds represent about 15 per
cent of the fruit and kernel constitutes about 34 per cent of seed. Similarly,
Iordanidow et al. (1999) found that the pulp, resulting after processing of apricot
mainly comes from the flesh of the fruit and it consists of 55 per cent of the total
fruit. The seeds contain kernels at 13.5 to 38.0 per cent of their weight. Sharma et
al. (2005) recorded length of apricot kernels as 3.58 to 4.52 mm and kernel
thickness as 5.27 to 6.42 per cent.
6
2.4 Physical properties of apricot stones and kernels
According to Fathollahzadeh et al. (2008), the physical properties of
stones are necessary for the design of instrument for processing, transportation,
sorting and separating. The physical properties of apricot kernels have been
evaluated as a function of moisture content varying from 3.19 to 17.46 per cent.
With increase in moisture content, kernel length, width, thickness, geometric
mean diameter and surface area increased. The sphericity varying from 59.79 to
62.21 per cent; while mass (g), thousand grains mass (g), volume (cm3) and true
density (kg/m3) ranged between 0.380 to 0.448 g, 381.6 to 447.9 g, 0.442 to
0.463 cm3 and 882.588 to 983.383 kg m-3 respectively in different samples of
apricot stones. The porosity and bulk density decreased from 52.68 to 51.33 per
cent and 471 to 406.8 kg m-3 respectively as varying moisture contents. The
coefficient of static friction on all surfaces increased as the moisture content
increased and the rupture strength in weakest direction (through length) decreased
from 23.443 to 16.620 N. Thus, moisture exerted a decisive role on the size
parameter of apricot stones and kernels.
Technological properties such as dimensions, geometric mean diameter,
sphericity, surface area, bulk density, true density, porosity, volume, mass, 1000-
unit mass, coefficient of static friction on various surface and rupture force in
three-axis, were determined at 82.34, 16.48 and 13.03 per cent moisture contents
for apricot fruits, apricot pits and apricot kernels, respectively (Fathollahzadeh et
al. 2008). Bulk densities of fruits, pit and kernels were reported to be 443.2,
539.4 and 540.1 kg m-3, the corresponding true densities were 940.7, 1045.5 and
1023.6 kg m-3 and the corresponding porosities were 52.87, 48.40 and 47.21 per
cent, respectively. Further, it was found that values for volume, mass and surface
area of fruits were larger than those of pits and kernels. Static coefficient of
friction of fruit on all surfaces (wood, glass, galvanize sheet and fiber glass sheet)
were measured and static coefficient of friction was less bout for pits and
kernels on glass and their value were 0.474 and 0.188, respectively. Rupture
force of fruit, pit and kernel were 10.11, 497.79 and 18.92 N through length,
7.98, 322.59 and 41.97 N through width and 7.01, 337.21 and 99.58 N through
thickness. Results showed that rupture force through length were minimum and
7
this result is very important factor in designing post harvest machines, especially
for apricot pit crusher machine (Ahmadi et al., 2009).
Polat et al. (2007) studied the effects of heating process and warping
effect on breaking of apricot pits and obtaining of its kernel without damage. For
this aim, heating process (350 oC) was applied to apricot pits. Heated pits were
fallen onto the rotating disc and they were warped to warping wall by centrifuge
effect. Three different disc revolution namely 400, 500 and 600 min-1 and four
different moisture contents of apricot pits namely 6.7, 15.5, 22.2 and 31.5 per
cent were used. The study revealed that increasing the moisture content caused
increase in amount of breaking with sound kernel. Increasing of disc revolution
increased ratio of damaged kernel. The highest breaking amount was determined
with heated pits that had 31.5 per cent moisture content and warped with 400
min-1 disk revolution. Haciseferogullari et al. (2007) studied physical and
chemical characteristics of the six samples of apricot (Prunus armeniaca L.)
fruits. These properties are necessary for the design of equipments for harvesting,
processing, and transportation, separating and packing. Technological properties
such as length and diameter of fruit, mass, volume of fruit, geometric mean
diameter, sphericity, bulk density, fruit density, porosity, projected area, static
and dynamic coefficient of friction were determined at 83.27 per cent (Zerdali),
77.79 per cent (Cataloglu), 82.1 per cent (Hacihaliloglu), 79.79 per cent
(Hasanbey), 82.31 per cent (Soganci) and 77.37 per cent (Kabaasi) moisture
content. The values of length, mass, geometric mean diameter and sphericity of
six different apricot fruits were established between 29.26 mm and 46.98 mm,
14.35 to 41.48 g, 28.99 to 41.15 mm, 0.876 to 0.991 per cent, respectively. Thus,
detailed bioengineering properties of fruit, stones and pits can be utilized for
designing of machine for their decortication.
2.5 Decortication of apricot stones
Decortication is the method of breaking nuts/stones to separate the
kernels. Reddy et al. (1995) developed a hand operated decorticator for apricot
nuts in Oil Technology Research Institute, Anantpur. However, the possibility of
using the decorticator in extraction of kernels from hardy stones of wild apricot is
8
yet to be explored. Similarly, for decortication of apricot stones decorticator has
been designed and developed which has been reported to decorticate 42 kg
pits/hour as against 2.25 kg pits/hour by manual decortication (Sharma et al.,
2005). The clearance between the two rollers for stones of different fruits has
been reported to be 8.25 to 9.11 mm for apricots and 6.58 to 7.28 for plum stones.
Gupta and Sharma (2009) reported that use of mechanical decorticator is most
appropriate for crushing of stones/pits with respect to ease of handling, efficiency
and economy of the operation. According to Dixit et al. (2010) mechanical
decortication and separation could not only save time and money but also reduce
women drudgery (due to manual breaking of stones to separate kernel). The
technology was reported to be suitable for promotion of entrepreneurship on the
processing of apricot oil from apricot kernel in the production catchment.
2.6 Kernel separation
The separation of kernels from the crushed mass is quite laborious and
time consuming operation. The kernel separation method using 20 per cent salt
solution has been optimize by Sharma et al. (2005) with the kernel separation
efficiency of 4.47 kg/hr in apricot, 2.783 kg/hr in peach kernel and 1.633 kg/hr in
plum kernels. Gupta and Sharma (2009) reported that dipping of crushed shells
and kernels in 25 per cent salt solution is optimum for separation of kernels.
However, dipping of kernels in salt solution is also likely to affect the taste and
quality with the apprehension of salt in the oil. Thus, there is need for further
standardization of the method for kernel separation using mechanical separation
beside other considerations.
2.7 Oil extraction
Traditionally, wild apricot oil is extracted manually by crushing the
kernels on pastle and mortar as well as pressing in between the hands. The quality
of this oil is considered better by the local tribal’s with a good pharmaceutical
significance. However, the method of oil extraction is quite cumbersome with
low yield. Thus, the use of oil press (power operated ghani) has been practiced
for oil extraction from stone fruit kernels. The oil yield from wild apricot by
using oil press method was found to be 40.42 per cent in apricot (Aggarwal et al.,
9
1974), against the oil recovery of 50.90 per cent obtained through the solvent
extraction method (Abd El Aal et al., 1986) while, Sharma et al. (2005) recorded
an oil yield of 34.5 per cent by using oil press against the value of 45.03 per cent
in solvent extraction.
Gupta and Sharma (2009) found that the oil yield from bitter kernelled
wild apricot obtained from Mandi, Shimla and Kinnaur areas in Himahcal
Pradesh ranged between 45.6 to 46.3 per cent and sweet kernelled resulted in oil
yield of 46.9 to 47.6 per cent. The use of table oil expeller was optimized for
extraction of oil from separated kernels with an oil yield of 38 to 40 per cent in
wild apricot fruit kernels (Gupta and Sharma, 2009). The available information
indicates that only cold extraction method comprising of passing of apricot
kernels in the oil press or oil expeller without any pre-treatment for extraction of
oil is used. However, pretreatment of raw material like soaking as well as
steaming is known to affect the yield and quality of oil and then calls for detailed
investigation.
2.8 Oil yield
Sherin (1994) recorded a yield of 46.5 per cent oil in apricot cultivar NJA
13 in Pakistan. According to Femenia et al. (1995) sweet apricot kernels
contained more oil (53g/100g kernels) than bitter kernels (43g/100g kernels). The
oil yield in apricot kernels was recorded as 43.03 per cent in chulli and 44.36 per
cent in new castle cultivar (Sharma et al. 2005).
According to Dwivedi and Dwivedi (2007) when the temperature of the
oil extraction apparatus reaches above 100 oC, the dough prepared on the oil
extraction apparatus, is spread at one end of the extraction rock and wetted with
about 50 to 75 ml water. This is the most important step, because the oil can be
extracted only as water suspension. The use of table oil expeller was optimized
for extraction of oil from separated kernels with an oil yield of 38 to 40 per cent
in wild apricot fruit kernels (Gupta and Sharma, 2009).
10
2.9 Physico-chemical characteristics of oil
2.9.1 Colour
The colour of oil besides visual appearance is usually compared in a
Lovibond Tinto meter using a 1 inch or 51/4 inch cell or by measuring the optical
density. Cruess (1958) reported that bitter apricot kernel oil obtained after
refining were light pale yellow in colour. Kamboj (2002) reported that the kernel
oils of apricot, peach and plum were yellow except Santa Rosa which was
reddish yellow in colour. Abd El Aal et al. (1986) showed that apricot kernel oil
was light yellow in colour having 35Y and 5R Tintometer Colour Units (TCU).
Gupta (2006) showed that the kernel oil from bitter apricot was deep yellow
whereas sweet kernel oil was light yellow in colour. The Tintometer colour unit
(TCU) also reflected the yellowness as predominant colour (6.4 to 6.9 TCU) in
bitter kernel oil followed by oil from sweet kernelled apricot with yellow as
predominant colour units (5.7 to 5.8 TCU) and red colour units ranged between
0.1 to 0.3 TCU in bitter kernel oil and 0.1 to 0.2 TCU in sweet kernel oils.
2.9.2 Composition of oil
Iordanidow et al. (1999) reported that apricot kernels contained 27.7 to
51.6 per cent oil 20.3 to 45.3 per cent protein. The kernels also contained sugar
(4.1 to 12.9 %), crude fibers (2.2 to 14.3 %) and minerals. The fatty acid
composition of apricot oil resembled to that of olive oil. The oil is reported to
contain 13.7 per cent saturated, 86 per cent unsaturated fatty acid,
linoleic/linolenic acid fraction (64.6 %) was reported to be comparable with
quality of the oil obtained in soyabean oil (Ciulei et al. 1973). Similarly, Alam
(2001) reported that the saturated and unsaturated fatty acid in apricot oil ranged
from 10.53 to 20.34 per cent and 79.66 to 89.47 per cent, respectively. Oleic acid
was found to be the predominant fatty acid (45.72 to 73.10 %) followed by
linoleic acid (15.21 to 42.57 %).
Similarly, Fatma et al. (2010) reported that the apricot seeds contained
high proportions of oil rich in α-tocopherol and oleic acid, an unsaturated fatty
acid. Genetic variation were also found among the cultivars, however bitterness
or sweetness was not significant. On the basis of two years data, total oil content
11
in different cultivars ranged between 42.77 to 54.92 per cent; oleic acid content
65.81 to 71.40 per cent; linoleic acid content 21.27 to 25.64 per cent; palmitic
acid content 5.29 to 6.66 per cent; stearic acid content 1.10 to 1.48 per cent and
palmitolic acid content 0.58 to 0.88 per cent. Oleic acid was negatively correlated
with linoleic acid, palmitic acid, palmitolic acid and α- tocopherol, which was
also correlated with α-tocopherol.
2.9.3 Lipid profile of extracted oil
The kernel oil from wild apricot have been traditionally used by local
tribal as a oil for cooking, body massaging oil and hair oil as it is known good for
eye sight, relief from joint pains etc. Therefore, to conform utility of the extracted
oil it should be evaluated for their fatty acid profile. According to Sharma et al.
(2003) the fatty acid composition of extracted oil shows significantly higher
proportion of unsaturated fatty acid comprising 91.08 to 91.73 per cent while
saturated fatty acid accounting for only 8.58 to 8.91 per cent of total fatty acid
thus exhibiting unsaturated/saturated ratio of 10.22 to 10.65:1. Therefore, the
kernel oil from apricot possesses special dietary importance.
Savage et al. (2001) reported that vitamin E isomers provide some
protection against oxidation of the lipids. So, a measurement of vitamin E
isomers is important due to their anti-oxidative effect and their positive
nutritional effects in human metabolism.
2.9.4 Acid value
The acid value of an oil or fat is defined as the number of mg of
potassium hydroxide required for neutralizing the free acid in 1 g of the sample
and expressed as the percentage of free acid (Ranganna, 2009). Generally, the
acid value is a measure of the extent to which the glycerides in the oil have been
decomposed by the action of enzyme lipase. The decomposition is accelerated by
heat and light. Rancidity is usually accompanied by free fatty acid formation and
the determination is often used as a general indication of the condition and
edibility of oils (Mayer, 1987).
Eckey (1954) reported an acid value of 0.2 to 4.0 (mg KOH/g) in apricot
kernel oil. The range of acid value in different samples of apricot oil has been
12
reported to be 1.07 mg KOH/g (Dhar & Chauhan, 1963); 0.12 mg KOH/g (Abd
El Aal et al., 1986); 3.6 mg KOH/g in wild apricot oil (Aggarwal et al., 1974). In
refined, bleached and deodorized (RBD) oil, the acid value however has been
found to be less than 4.0 mg KOH/g (Anonymous, 2012a). According to Indian
Food Laws, the acid value of almond oil shall not exceed 4.0 mg KOH/g (FSSA,
2006). Sharma et al (2005) reported an acid value within the range of 2.26 to 4.31
mg KOH/g in apricot kernel oils whereas; Gupta and Sharma (2009) reported that
the acid value ranged within 2.27 to 2.78 mg KOH/g in bitter kernelled apricot oil
and 4.27 to 4.35 mg KOH/g in sweet kernelled oils. Further, Bachheti et al.
(2012) reported acid value of 4.05 mg KOH/g in wild apricot oil from Gharwal
region of Uttarakhand.
2.9.5 Iodine value
The iodine value of an oil or fat is defined as number of grams of iodine
absorbed by 100 grams of sample. The glycerides of the unsaturated fatty acids
present (particularly of oleic acid series) unite with a definite amount of halogen
and the iodine value is therefore a measure of the degree of unsaturation. It is
constant for a particular oil or fat, but the exact figure obtained depends on the
particular technique employed. According to Pearson (1976) the range of iodine
value in different fats vary between 30 to 70 g I2/100 g in animal fats (butter, lard
etc); 80 to 110 g I2/100 g in non drying oils (olive oil, almond oil etc); 80 to 140
g I2/100 g in semi drying oils (cotton seed oil, sesame oil, soya oil) and 125 to
200 g I2/100 g in drying oils (linseed oil, sunflower oil etc.).
The iodine value is often the most useful index for identifying oil or at
least placing it into a particular group. It is reported that the less unsaturated fats
with low iodine values are solid at room temperature, or conversely oils that are
more highly unsaturated are liquids (thus representing a relationship between the
melting points and the iodine values). Besides, the degree of unsaturation (i.e. the
higher the iodine value), the greater is the liability of the oil or fat to go rancid by
oxidation (Thimmiah, 1999). A direct fall in iodine value of oil was also observed
by Handoo et al. (1992). Eckey (1954) reported an iodine value of 97 to 109 g
I2/100 g in apricot kernel oils. Dhar and Chauhan (1963) recorded only 87.2 g
I2/100 g as iodine value in apricot oil.
13
Further, Morpankha and Chawaru cultivars of apricots in Kumaon and
Ladakh region were reported to contain 109.9, 99.58 and 80.82, 123.0 g I2/100 g
iodine values respectively (Dang et al., 1964 and Kapoor et al., 1987). The wild
apricot kernel oil had an iodine value of 104.1 g I2/100 g (Aggarwal et al., 1974).
In refined, bleached and deodorized (RBD) apricot oil, the iodine value ranged
from 104 to 112 g I2/100 g (Anonymous, 2012a) and 98 to 110 g I2/100 g
(Chakaraborty and Talapatra, 1965). Abd El Aal et al. (1986) reported an iodine
value of 103.8 g I2/100 g in apricot kernel oil, while Kamboj (2002) recorded the
iodine value of 95.5 g I2/100 g in wild apricot kernel oil. Similarly, Sharma et al.
(2005) reported iodine value of 100.2 to 112.9 g I2/100 g in kernel oil from
apricots grown in Himachal Pradesh. Gupta and Sharma (2009) recorded 110.4 to
112.7 g I2/100 g iodine value in sweet kernelled apricot oil and 100.2 to 100.4 g
I2/100 g in bitter kernelled apricot oil. Bachheti et al. (2012) reported iodine
value of 102.0 g I2/100 g in oil from wild apricot kernels.
2.9.6 Peroxide value
Peroxides are the main initial product of auto-oxidation and can be
measured by various methods based on their ability to liberate iodine from
potassium iodide or to oxidize ferrous to ferric ions. Peroxide number is a
measure of oxidative rancidity, which is expressed as milli equivalent of peroxide
per kg of lipids. Various successful attempts have been made to correlate
peroxide value with development of rancid flavour. According to Jacob (1958)
high peroxide value is the indicator of spoilage in unsaturated fatty acids and
shall not exceed 125.0 meq/kg. However, the amount of oxygen that must be
absorbed and formed to produce rancidity also vary with composition of oil,
presence of antioxidant and condition of oxidation (Nawar, 1985). Generally, the
more unsaturated a fat is, the faster it will go rancid (Anonymous, 2012a).
In apricot oil, the peroxide value has been found to be 0.12 meq/kg by
Abd El Aal et al, 1986. In different samples of commercial apricot oil the
peroxide value has been reported to be 10.0 meq/kg (Anonymous, 2012a); 5.39 to
6.63 meq/kg (Kamboj, 2002) and 4.38 to 5.39 meq/kg (Sharma et al., 2005).
Further, Gupta and Sharma (2009) reported that peroxide value ranged between
5.12 to 5.27 meq/kg in bitter kernelled oil and 4.32 to 4.40 meq/kg in sweet
14
kernelled oil. Ozcan et al. (2010) recorded peroxide value in between 0.83 to 8.29
meq/kg in oil from different cultivars of apricot.
2.9.7 Saponification value
The saponification value of an oil or fat is defined as the number of mg of
potassium hydroxide required to neutralize the fatty acids resulting from the
complete hydrolysis of l g of the sample. The low molecular weight esters of the
fatty acids require more alkali for saponification, therefore the saponification
value is inversely proportional to the molecular weights of the fatty acids in the
fat/oil (Pearson, 1976). As many oils have somewhat similar values (e.g. those in
the olive oil series fall within the range 188 to 196 mg KOH/g), thus, the
saponification value is not, as useful for identification purposes as the iodine
value .The saponification value is of most use for detecting the presence of
coconut oil (255 mg KOH/g), palm kernel oil (247 mg KOH/g) and butter fat
(225 mg KOH/g) which contain a high proportion of the lower fatty acids.
Paraffin with a negligible saponification value, can also be detected and
estimated if present as an adulterant.
According to Eckey (1954) the saponification value in apricot oil ranged
between 188 to 200 mg KOH/g, while, Abd El Aal et al. (1986) recorded a value
of 189.7 mg KOH/g in apricot oil. Similarly, Morpankha and Chawaru cultivars
in Kumaon region were found to contain 191.3 and 193.8 mg KOH/g
saponifiation value (Dang et al., 1964). While, wild apricot oil showed the
presence of slightly lower (188.8 mg KOH/g) level of saponification value
(Aggarwal et al., 1974). Kamboj (2002) reported saponification value of 194.9
mg KOH/g in apricot kernel oil whereas Sharma et al. (2005) recorded a range of
190.2 to 194.4 mg KOH/g in apricot kernel oils. In refined, bleached and
deodorized (RBD) apricot oil, the saponification value ranged from 185 to 195
mg KOH/g (Anonymous, 2012a). According to Gupta and Sharma (2009) the
saponification values of sweet and bitter apricot kernel oils ranged from 193.4 to
193.6 mg KOH/g and 189.8 to 191.3 mg KOH/g respectively. Bachheti et al.
(2012) reported saponification value 190.0 mg KOH/g in wild apricot oil from
Gharwal region of Uttarakhand.
15
2.9.8 Hydrocyanic acid (HCN)
The kernels of stone fruits are reported to contain a cyanogenic glucoside which
upon hydrolysis yield HCN. The lethal dose of HCN for human being is estimated to be
0.5 to 3.5 mg/kg of body weight. In different fruit kernels varying levels of amygdalin and
HCN has been recorded. According to Winton and Winton (1959), an HCN content of
0.06 per cent was recorded in plum kernels where as apricot kernels also contain 0.06 per
cent. Stosic et al. (1987) conducted toxicological test on mice and found that apricot
contain 8.1 mg/kg of HCN as toxic compound. Amygdalin, a cyanogenic glucoside ranges
from 2.5 to 3.5 per cent (dry wt.) of bitter almond seeds. Amygdalin has also been detected
at low levels in some sweet almond cultivars (Mc Carty et al., 1952). Amygdalin is an
association of genitiobiose and mandelic acid (β-gentiobiose of the nitrate of α-
hydroxyphenyl acetic madelo nitrate acid). On the hydrolysis, it is split by the inherent
enzyme β-glucosidase (emulsin) into two molecules of glucose, benzaldehyde and HCN
(Brower, 1969). However, Amar cultivar of apricot did not show the presence of any HCN
in its kernel (Abd EI Aal et al., 1986). Sharma et al. (2005) recorded as 6.47 mg/kg HCN
in apricot oil. Femenia (1995) observed that amygdalin content was very high (5.59
mg/100mg) in bitter apricot kernels. According to Gupta and Sharma (2009) dipping of
kernels in 25 per cent salt solution prior to oil extraction brought about complete removal
of bittering component, HCN in oil. Further, blanching of kernels in boiling water for 40 to
50 min helps in complete detoxification of apricot kernels from the HCN content. Among
different methods of detoxification the use of 10 per cent sodium thiosulphate was found to
be most effective for complete detoxification.
Therefore, it is essential to detoxify this toxic compound before utilization of
kernel oils and press cake as edible and pharmaceutical purposes.
2.10 Utilization of kernel press cake
The press cake left after oil extraction contains amygdalin which yields
about 0.06 per cent HCN (hydrocyanic acid), upon hydrolysis. It is known to be
utilized as fuel and fertilizer as it is considered unfit for cattle feed due to
presence of HCN. Chemically it contains nitrogen (6.64 per cent), phosphoric
acid (2.2 per cent) and potash (1.64 per cent). The seed cake of bitter apricot is
reported to yield about 1.6 per cent of volatile oil. Iordanidow et al. (1999)
reported that the kernel meal can be used for protein isolation by protein
16
extraction, iso-electric precipitation and freeze drying. The protein products at a
75 per cent yield had low protein content (up to 53.5 %), were light coloured and
had comparable functional properties to commercial soya isolate.
2.11 Volatile Oil
Volatile oils are extracted from stone fruit kernels and left over press cake after oil
extraction. The benzaldehyde is the chief constituent of these oils and extraction is done by
steam or water distillation. Gildemeister and Holfmann (1974) reported that bitter almonds
yield from 0.5 to 0.7 per cent, apricot kernels from 0.6 to 1.8 per cent of volatile oil.
According, to Tilakratne (2007) diluting press cake with water (1:10) followed by
immediate distillation yielded about 30 ml. of volatile oil, which contained about 40 per
cent of benzaldehyde, but the essential oil also contained appreciable amount of HCN
(152 mg/100g). In order to remove HCN from the distillate, the volatile oil obtained after
distillation of slurry (press cake + water in the ratio of 1:10) without maceration was re-
distillate with 3 per cent each of CaO and FeSO4, which resulted in 3.3 per cent of volatile
oil with 75 per cent benzaldehyde without HCN.
2.12 Anti-fungal activity of volatile oil
According to Tilakartne (2007) the anti microbial activity of apricot
kernel oil and volatile oil was evaluated against both Escherichia coli and
Staphyloccocus aureus. It was found that volatile oil extracted from press cake
exhibited good anti-microbial activity against both the micro organisms i.e.
Staphyloccocus aureus and Escherichia coli. The inhibition zone developed by
the volatile oil against Staphyloccocus aureus and Escherichia coli measured to be
3.4 cm and 1.2 cm diameter respectively. Apricot oil, however did not exhibit any
anti-microbial activity against Staphyloccocus aureus. While apricot oil showed
good anti-microbial activity against Escherichia coli with the development of
inhibition zone of 2.0 and 1.4 cm diameter respectively. In contrast to these
observations Hammer et al. 1999, recorded no inhibitory effect on Escherichia
coli and Staphyloccocus aureus which might be due to low concentration in the
study. Yigit et al. (2009) also tested the apricot kernel extract against human
pathogenic micro-organism using a disc-diffusion method and evaluated the
minimal inhibitory concentration (MIC) values. The most effective antibacterial
17
activity was observed in the methanol and water extracts of bitter kernels and in
the methanol extract of sweet kernels against the gram-positive bacteria
(Staphylococcus aureus). Additionally, the methanol extracts of the bitter kernels
were very potent against the gram-negative bacteria with a MIC value of 0.312
mg/ml for Escherichia coli. Similarly, significant anti-candida activity was also
observed with the methanol extract of bitter apricot kernels against Candida
albicans consisting of a 14 mm in diameter of inhibition zone and a 0.625 mg/ml
MIC value. Thus, volatile oil from apricot kernels need to be evaluated for
antimicrobial activity against different micro-organisms.
CHAPTER–3
MATERIALS AND METHODS
The present investigation entitled, "Refinement of technology for
extraction and utilization of apricot kernel oil and press cake" was conducted in
the Department of Food Science and Technology, Dr. Y.S. Parmar University of
Horticulture and Forestry, Nauni-173230, Solan (H.P.) during the years 2010-
2013. The experimental details and technique used in these studies are described
under following heads:
3.1 Raw material
Wild apricot stones in bulk left after utilization of edible portion were
processed from Karsog area in Mandi district of Himachal Pradesh (1850 meter
above mean sea level) and brought to the department of Food Science and
Technology, UHF Nauni for experimentation. The stones were utilized for
conducting following three studies
1. Development of method for mechanical separation of apricot kernels after
decortication.
2. Optimization of parameter for oil extraction.
3. Extraction and utilization of volatile oil from apricot kernel press cake.
3.2 Development of method for mechanical separation of apricot kernels after decortication
The suitability of mechanical separator was evaluated for simultaneous
separation of kernels from the crushed apricot stone mass. The mechanical
separator consisted of inclined belt moving in upward opposite direction to allow
rolling of kernels and carrying forward the shells. The inclination angle of the
belt was optimized on the basis of angle of static friction of apricot stones and
kernels on different surfaces. Four surfaces (wood, glass, paper and rubber) were
evaluated to optimize the surface on belt for development of inclined plane type
mechanical separator for apricot kernels. Angle of static friction of apricot stones,
19
kernels and shells on four surfaces was determined with the help of inclined plane
instrument with adjustable slope. In order to make moving inclined plane, the
rubberized belt was optimized on a moving surface for separation of apricot
kernels. The suitability of rubber for its use as a belt was used in the mechanical
separator placed in inclination position about 22.5o from base and move in
opposite direction from the flow of decorticated stones (shells and kernels) which
are dropped from the height to allow the kernels to roll on the belt while shells
being coarse are carried by the moving belt to other end of the separator. The
length of the belt was kept 6 feet with speed of 5 rpm which was found optimum
to achieve separation. The belt was moving with the help of 2 hp motor. The
assembly was provided with forced air fan facility to allow separation of dust and
fine shells/kernels particles while moving on the belt. The efficiency of kernel
separation was compared with the kernel separated by using gravity separation
method (Gupta and Sharma, 2009) which served as the control.
3.2.1 Effect of soaking treatments on the efficiency of kernel separation in mechanical separator
Effect of soaking of apricot stones/kernels in water on the efficiency of
kernel separation in mechanical separator was optimized. Four treatments viz.
mechanical decortication without soaking followed by separation in salt solution
(control) (S1), soaking of apricot stones in water for overnight followed by
decortication and kernel separation in mechanical separator (S2), soaking of
decorticated apricot stones mass in water for overnight followed by kernel
separation in mechanical separator (S3) and mechanical decortication of pre-
soaked apricot stones followed by further soaking of decorticated stone mass
prior to separation in mechanical separator (S4) were studied to standardize
optimum soaking treatment (Table 1). The effect of soaking on change in
physical parameter of apricot stones as well as kernels was studied. The treatment
giving optimum rolling of the kernels on the moving belt was rated as most
appropriate.
20
Table 1: Soaking treatments of apricot stones and kernels to optimize kernel separation efficiency in mechanical separator
Treatment No.
Particulars
S1 Mechanical decortication without soaking followed by separation in salt solution (control).
S2 Soaking of apricot stones in water for overnight followed by mechanical decortication and kernel separation in mechanical separator.
S3 Soaking of mechanically decorticated apricot stones mass in water for overnight followed by kernel separation in mechanical separator.
S4 Mechanical decortication of pre-soaked apricot stones for overnight followed by further soaking of decorticated stone mass for another 12 hours prior to separation in mechanical separator.
3.3 Optimization of parameters of apricot kernel for improving yield and quality of oil
Apricot kernels after separation in mechanical separator were used for
extraction of oil through Table oil expeller. Suitability of soaking apricot kernel
in different proportion of water with or without steaming prior to oil extraction
was standardized as per treatments shown in Table 2. The yield and quality of oil
extracted through Table oil expeller after different pretreatments was compared
with the oil extracted through Soxtec oil extraction apparatus. Treatment showing
maximum oil yield was optimized for the extraction of oil.
Table 2: Detail of pretreatments of apricot kernels prior to extraction of oil
Treatment No.
Particulars
O1 Oil extraction in Soxtec oil extractor from apricot kernels without adding water.
O2 Oil extraction in Table oil expeller from apricot kernels without adding water (Control).
O3 Oil extraction in Table oil expeller after soaking by addition of 5% (w/w) water in apricot kernels.
O4 Oil extraction in Table oil expeller after soaking by addition of 10% (w/w) water in apricot kernels.
O5 Oil extraction in Table oil expeller after steaming of apricot kernels (5 psi) for 15 min without prior soaking in water.
O6 Oil extraction in Table oil expeller after soaking by addition of 5% water in apricot kernels followed by steaming (5 psi) for 15 min.
O7 Oil extraction in Table oil expeller after soaking by addition of 10% water in apricot kernels followed by steaming (5 psi) for 15 min.
21
3.3.1 Solvent extraction
The apricot kernels were ground to a coarse powder in a household mixer
cum grinder prior to its use for oil extraction purposes. 20 g of powdered sample
was weighed in respective thimbles and placed in Soxtec Oil Extraction
Apparatus (M/S Velps Scientifica, SRL, Italy) preprogrammed (Temperature 130
°C, immersion time 360 minutes; washing time 30 minutes; recovery time 20
minutes) for oil extraction using petroleum ether (40-60 oC Boiling Point) as a
solvent. After six hours of extraction process, the crude oil was collected after
recovering about 90% of the solvent and allowing the rest to evaporate in the
oven (Ranganna, 2009). The extracted oil was then packed in pre-sterilized glass
bottles for its later use in analytical purposes.
3.3.2 Table oil expeller (Y2K)
Table oil expeller (Y2K) is a 24 patti screw type oil expeller (M/S Sardar
Engineering Company, Kanpur, India) driven by 5HP motor. In the experiment
the kernels were fed from the hopper at a predetermined flow rate, which were
pressed in between the screw roller (worm) and sidewalls of the expeller. The
kernels were passed 3-4 times until a very thin slip of press cake was obtained.
The extracted oil was filtered through a filter press, which consisted of different
layers of thick nylon cloth through which oil was pumped from the motor for
filteration. The clear oil was then packed in amber coloured plastic bottles (200
ml capacity) and kept in cool dry place until used for further experimentation.
3.4 Extraction and utilization of volatile oil from apr icot kernel press cake
Hydro-distillation apparatus consisted of stainless steel heating unit
capacity 10 litres. The heating pan was provided with a false bottom for placing
solid residue to avoid burning during heating. The vapours were carried through a
vertical tube which was cooled in a horizontally placed stainless steel condenser
and collected in vapour collection tube. The volatile oil containing hydro-
distillate floating in the glass tube was collected periodically. After collection of
about 1 % of the distillate, the diluted cake was removed and another batch was
fed. The press cake left after oil extraction was utilized for extraction of volatile
22
oil in hydro-distillaion apparatus and clevenger’s apparatus. The method was
optimized for separation of benzaldehyde from the mixture of volatile oil
containing HCN. Four treatments T1 (Diluting press cake with water (1:10)
followed by distillation to collect 1 % distillate), T2 (Diluting press cake with
water (1:10) maceration at 50°C for 12 hours followed by distillation to collect 1
% distillate), T3 (Re-distillation of distillate (100 ml) from T1 with 3% each of
CaO and FeSO4 to collect 50 % of volatile oil), T4 (Re-distillation of distillate
(100 ml) from T2 with 3% each of CaO and FeSO4 to collect 50 % of volatile oil)
were used for extraction of volatile oil from the kernel press cake Table 3. Best
treatment with maximum yield of benzaldehyde was optimized for the extraction
of volatile oil from apricot kernel press cake.
Table 3: Detail of pretreatments of press cake followed by extraction of volatile oil
Treatment No.
Particulars
T1 Diluting press cake with water (1:10) followed by distillation to collect 1 % distillate (100 ml)
T2 Diluting press cake with water (1:10) maceration at 50°C for 12 hours followed by distillation to collect 1 % distillate (100 ml)
T3 Re-distillation of distillate (100 ml) from T1 with 3% each of CaO and FeSO4 to collect 50 % of volatile oil
T4 Re-distillation of distillate (100 ml) from T2 with 3% each of CaO and FeSO4 to collect 50 % of volatile oil
3.5 Analysis of stones and kernels
3.5.1 Size of stones and kernels
Size parameters comprising of length, breadth and thickness of stones and
kernels were recorded with the help of Digital Vernier Caliper and
expressed in mm.
3.5.2 Geometric Mean Diameter, Sphericity and Coefficient of Static Friction
Ten apricot stones randomly selected and their kernel were analyzed for
their size parameters like length (l), breadth (b), thickness (t), geometrical mean
diameter (Dg) in mm and sphericity (O). Geometrical dimensions were measured
by using Vernier Calliper with accuracy of 0.01mm. On the basis of three
23
dimensions [length (l), breadth (b) and thickness (t)], geometrical mean diameter
and sphericity of the apricot stones/kernels was calculated by using following
equations (Mohsenin, 1970; Jain and Bal, 1997).
Dg= (l.b.t) 1/3 (1) Dg: Geometric mean diameter
O = [(l.b.t)1/3/l]x100 (2) O: Sphericity
The angle of static friction of apricot stones, kernels and shells on four
surfaces including wood, glass, paper and rubber was determined using inclined
plane instrument. For determining Angle of static friction (θ), the sample (stones,
kernels, shells) was placed on the respective surface with adjustable slope
(Inclined plane instrument). The angle, at which the kernels started to slip, was
indicated as angle of static friction (θ).
3.6 Physico-chemical characteristics of extracted oil
3.6.1 Colour
Instrumental colour of oil was measured in a Lovibond Colour Tintometer
Model E, AF-900 (Tintometer Ltd., Salisbury, U.K.) using one inch cell. The
Lovibond Tinotometer is a subtractive colourimeter based on direct observation
of illuminated sample through a viewing tube. The instrument is provided with
sets of red, yellow and blue glass slides to be used as permanent standards
(Ranganna, 2009). The results were then expressed as red, yellow and blue colour
units (TCU) and discussed on the basis of dullness. The value of colour, which is
lowest, expressed the amount of dullness. The lowest value was then combined
with equal values of other two colours to form a like value of neutral tint or
dullness. The remaining two colours were combined in equal values of the lower.
Thus, red and yellow formed equal units of orange, yellow and blue formed green
and red and blue resulted in violet. The balance of units of the remaining colour
staying unchanged was referred to as predominant colour.
3.6.2 Acid value
Acid value of apricot kernel oil was estimated by titrating a known weight
of sample (10g) containing 50 ml neutral solvent (25 ml ether + 25 ml 95 %
alcohol + 1% phenolphthalein) against 0.1N KOH solution using phenolphthalein
24
as an indicator (FSSAI, 2012). The acid value was calculated by using following
expression:
Titre x Normality of KOH x 56.1 Acid value (mg KOH/g oil) = -------------------------------------------------
Weight of sample (g)
3.6.3 Iodine value
Iodine value was estimated according to Wijs (carbon tetrachloride-acetic
acid solvent) method (FSSAI, 2012). The oil sample (0.26-0.32 g) was mixed
with carbon tetrachloride (25 ml) followed by addition of Wijs solution and then
stored in dark for one hour. After addition of 15 ml of 15 per cent Kl and 100 ml
distilled water, the solution was titrated against 0.1 N sodium thiosulphate using
starch solution as an indicator. The iodine value was then calculated by
subtracting the sample titre from the blank titre using following expression:
(Blank titre - Sample titre) x Normality of Na2S2O3 x 12.69 Iodine value = ------------------------------------------------------------ (g l2 /100 g oil) Weight of sample (g)
3.6.4 Peroxide value
Peroxide value was estimated by taking the sample (5g) mixed with 30ml
Acetic acid- chloroform solution containing saturated KI solution and titrated
against 0.1 N sodium thiosulphate using starch as an indicator and calculated as
milli-equivalent peroxide per kg sample (FSSAI, 2012). The peroxide value was
calculated by using following expression:
(Sample titre- Blank titre) x Normality of Na2S2O3 Peroxide Value = ----------------------------------------------------------- x 1000 (meq/kg oil) Weight of oil (g)
3.6.5 Saponification Value
Saponification value of apricot kernel oils was estimated according to
standard method (FSSAI, 2012). The known weight of sample (1 g) was mixed
with alcoholic potassium hydroxide (25 ml) and the mixture was refluxed for 30
minutes to completely saponify the sample and then titrated against 0.5 N HCI
using phenolphthalein as an indicator. Blank titration was carried out along with
25
the sample. Saponification value of the oil was then calculated by using the
expression as under:
(Blank titre- Sample titre) x 28.05 Saponification value = -------------------------------------------- (mg KOH /g oil) Weight of oil (g)
3.6.6 Hydro-Cyanic Acid (HCN)
3.6.6.1 Qualitative method
To pre-weighed sample (10 g apricot kernels or 10 ml apricot kernel oil),
2 ml freshly prepared 3 per cent FeS04.7H20 solution was added followed by
addition of single drop of 1 per cent FeCI3.6H20 solution. After proper mixing, 10
per cent NaOH solution was added drop wise until no further precipitate formed
followed by dissolving of precipitates by adding diluted H2SO4 (1+9) solution.
The development of Prussian blue colouration indicated the presence of HCN
(AOAC, 1995).
3.6.6.2 Quantitative method (Alkaline-titration method)
Alkaline-titration method was followed for quantitative estimation of
hydro-cyanic acid in apricot kernels and oil. 20 g sample was mixed with 200 ml
water and allowed to stand for 2 hours for complete hydrolysis of amygdalin to
HCN. The mixture was then steam distilled to collect 150-160 ml of distillate in
NaOH solution (0.5g in 20 ml H20) followed by its dilution to 250 ml. 100 ml
aliquot containing 8 ml 6N NH4OH and 2 ml 5 per cent Kl (Pottasium Iodide)
solution was then titrated against 0.02 N AgNO3 to a faint permanent turbid
colour (AOAC, 1995). The HCN content (mg/100g) in the sample was then
calculated using following expression:
Titre x 1.08 x Volume made up x Aliquot taken HCN (mg/100g) = ----------------------------------------------------------- x 100 Sample taken x Distillate taken 3.6.7 Lipid profiling/fatty acid composition
The fatty acid estimation of the apricot kernel oil was determined
according to the method of Metcalfe et al. (1966) by converting them in to
respective fatty acid methyl esters and by using gas liquid chromatography
26
(GLC). Methyl esters of the fatty acids were dissolved in hexane and analyzed by
Gas Chromatograph (GC) on a 2 meter column packed with either 3% SE/30 or
10% DEGS on 80-100 mesh Gas-Chrom Q. Retention times and peak areas were
determined by comparison with respective standards. Methyl esters of the fatty
acids (FA) were formed with BF3-methanol. A known amount of internal
standard (C15:0) was added prior to derivatization of standards and samples. Peak
areas were measured with a Shimadzu CR1A® recording integrator. Recovery
values and constants were determined and used as correction factors.
3.6.8 Vitamin E (Tocopherols)
Sample for estimating of vitamin E (tocopherols) was prepared by
refluxing 1 g of oil containing 10 ml absolute alcohol and 20 ml 1M acidic alcohol in 100 ml flask fitted with reflux condenser for 45 min. Upon cooling, the
sample was transferred to separating funnel along with 2x50 ml water to extract the unsaponifiable matter with 5x30 ml di-ethyl ether, followed by evaporation of combined extract at low temperature under the stream of nitrogen. The residue
obtained was dissolved immediately in 10 ml absolute alcohol.
To aliquot of the sample and standard (0.3-3.0 mg vitamin E) in 20 ml
volumetric flasks, 5 ml absolute alcohol and 1 ml concentration nitric acid was
added drop wise with constant swirling followed by heating at 90 °C for 3
minutes. Upon rapid cooling, the volume was adjusted to 20 ml with absolute
alcohol. The absorbance of samples and standard was measured at 470 nm
against a blank containing 5 ml absolute alcohol and 1 ml conc. nitric acid treated
in a similar manner (Pearson, 1976). The vitamin E in the sample was calculated
from the standard curve and expressed as µg/g.
3.6.9 Benzaldehyde content in volatile oil
A known volume of sample was pipetted out into distillation flask. After
addition of water, 100 ml distillate was collected. Aliquot of distillate was then
diluted with 10 per cent ethyl alcohol to produce absorbance (A) of sample at 249
nm, using 10 per cent of ethyl alcohol blank. Absorbance of standard
benzaldehyde solution was determined at 249 nm against blank (A') of 10 per
cent ethyl alcohol and standard curve was plotted (AOAC, 1995). Benzaldehyde
27
concentration from absorbance (A) was determined at 249 nm and standard curve
and average of 1 ppm benzaldehyde (A) was calculated from following
expression:
Concentration of benzaldehyde in ppm = (A/ A') x F
Where, F is dilution factor.
3.6.10 Antifungal activity of volatile oil
Apricot volatile oil extracted from press cake was evaluated for its
antifungal property against different fungi namely Fusarium sp., Sclerotium sp.
and Macrophomina sp. obtained from Department of Plant Pathology, Dr.
Yashwant Singh Parmar University Nauni. The active cultures of fungi were
maintained and multiplied on potato dextrose agar medium. The apricot volatile
oil was tested in vitro by using the Poisoned Food Technique in Completely
Randomized Design (CRD) to study the inhibitory effect of these oils on mycelial
growth of different fungi. These oils were evaluated at different concentrations
i.e. 5 per cent, 10 per cent, 15 per cent and 20 per cent against the pathogenic
fungi.
Double strength potato dextrose agar medium was prepared in distilled
water and sterilized in autoclave at 1.05 kg/cm3 pressure and 121oC for 20
minutes. Simultaneously, double concentrations of volatile oil were also prepared
in sterilized distilled water. Oil suspensions were added separately to equal
quantities of double strength potato dextrose agar medium aseptically before
pouring into petri plates. After the solidification of medium, these plates were
then inoculated with 2 mm diameter mycelial bit of different pathogenic fungi
taken from actively growing 5 days old culture. A control treatment was also
maintained in which only plain sterilized distilled water was added to double
strength medium. Each treatment was replicated thrice. The inoculated plates
were incubated at 28±1oC. The observation was recorded in the form of radial
growth of pathogenic fungi in millimeter (mm) daily until the control plates were
fully covered with the mycelium. Per cent inhibition was calculated as described
by Vincent (1947):
I = C-T x 100 T
28
Where, I = Per cent inhibition.
C = Growth of fungus in control (mm).
T = Growth of fungus in treatment (mm).
3.7 STATISTICAL ANALYSIS
The data on physico-chemical characteristics of apricot stones, kernels, oil
and volatile oil were analyzed statistically by using Factorial Completely
Randomized Design (CRD Factorial) (Cochran and Cox, 1967) and Logarithmic
Transformation (Gomez and Gomez, 1984). Triplicate determinations were made
for each parameter.
CHAPTER–4
EXPERIMENTAL RESULTS
The present investigation entitled “ Refinement of technology for
extraction and utilization of apricot kernel oil and press cake” was conducted in
the Department of Food Science and Technology, Dr Y S Parmar University of
Horticulture and Forestry, Nauni, Solan (H.P.) during the year 2010-2013. The
results of the study presented in tables 4.1-4.10 are described as under:
4.1 Development of method for mechanical separation of apricot kernels after decortication for development of mechanical separator
4.1.1 Optimization of coefficient of static friction
The angle of static friction of apricot stones and kernels on different
surfaces was found to vary between 20.0 to 22.8o on wood, 9.6 to 14.0o on glass,
13.8 to 16.8o on paper and 22.2 to 25.3o on rubber surface. The highest angle was
found on rubber (25.3o). Soaking of apricot stones brought about significant
improvement on the angle of static friction of stones and kernels. The mean value
of angle of static friction of soaked kernels was recorded as 21.0o on wood, 10.2o
on glass, 14.5o on paper and 22.5o on rubber against 19.0o on wood, 9.0o on glass,
13.0o on paper and 22.0o on rubber in un-soaked material (Table 4.1). Thus, on
the basis of angle of static friction of soaked apricot kernels on rubber, the
inclination angle of rubberized belt in mechanical separator was optimized as
22.5o from the base.
4.1.2 Effect of soaking treatments on moisture and size parameter of apricot stones and kernels
Data presented in Table 4.2 represent the effect of soaking treatments on
the moisture content and size parameters of apricot stones and kernels. As
expected, soaking of apricot stones prior to decortication (D2), soaking of
decorticated stone mass (D3) as well as soaking of stones before and after
decortication (D4) brought about significant increase in moisture content of
stones as well as kernels.
30
Table 4.1: Effect of soaking treatments of decorticated apricot stone fractions on the angle of static friction (θ) of stones, kernels, shells and mixture of shells and kernels on different rolling surfaces
Stone Fraction
Angle of static friction (θ)
Stones/Pits Kernels Shells Shells+Kernels
Unsoaked Soaked Mean Unsoaked Soaked Mean Unsoaked Soaked Mean Unsoaked Soaked Mean
Wood 21.0 22.0 21.5 19.0 21.0 20.0 22.0 22.5 22.3 22.0 23.5 22.8
Glass 11.5 12.5 12.0 9.0 10.2 9.6 12.5 13.0 12.8 12.0 13.0 12.5
Paper 14.0 16.0 15.0 13.0 14.5 13.8 15.5 17.0 16.3 16.0 17.5 16.8
Rubber 23.0 24.0 23.5 22.0 22.5 22.3 24.0 25.5 24.8 24.5 26.0 25.3
CD(0.05) 0.98 1.01 0.78 0.83 1.09 0.68 0.96 0.68 0.69 1.15 0.76 0.66
Fig: 1. Effect of soaking prekernels, shells and shells+kernels on different
Fig: 2. Effect of soaking pre-
0
5
10
15
20
25
30
Un
soa
ke
d
So
ak
ed
Me
an
Un
soa
ke
d
Stones
70.5
71
71.5
72
72.5
73
73.5
74
74.5
75
D1
Sphericity (%)
Effect of soaking pre-treatment on angle of static friction (θ) of apricotkernels, shells and shells+kernels on different surfaces
-treatment on sphericity (%) of apricot kernels
So
ak
ed
Me
an
Un
soa
ke
d
So
ak
ed
Me
an
Un
soa
ke
d
So
ak
ed
Me
an
Kernels Shells Shells+Kernels
Angle of static friction (θ)
D2 D3 D4
Treatment
SPHERICITY (%)
[(l.b.t)1/3/l]x100
apricot stones,
kernels
Wood
Glass
Paper
Rubber
SPHERICITY (%)
[(l.b.t)1/3/l]x100
31
Table 4.2: Effect of soaking treatments on the moisture and size parameters of apricot stones and kernels.
NOTE: - * 20 kg of stones were used for each batch of experimentation Figure in parentheses indicate per cent weight gain after soaking treatment
Treatment*
Particulars Weight after
soaking (kg)
MOISTURE (%)
LENGTH (mm)
BREADTH (mm)
THICKNESS (mm)
GEOMETRIC MEAN
DIAMETER (mm) (l.b.t)1/3
SPHERICITY (%) [(l.b.t)1/3/l]x100
Stone Kernel Stone Kernel Stone Kernel Stone Kernel Stone Kernel Stone Kernel
D1 Mechanical decortication of apricot stones without soaking (control)
- 7.8 4.4 20.0 12.0 15.9 9.0 10.3 6.0 14.8 8.6 74.3 72.1
D2 Soaking of apricot stones in water for overnight followed by mechanical decortication
22.1
(10.5)
15.7 17.0 20.5
12.1
16.4
9.1
10.6
6.1
15.3 8.7 74.5 72.4
D3 Soaking of mechanically decorticated apricot stones mass in water for overnight
23.0
(15.2)
18.4 28.5 -
12.2
-
9.3
-
6.2
- 8.9 - 72.9
D4 Mechanical decortication of pre-soaked apricot stones followed by further soaking of decorticated stone mass for overnight
23.4
(17.0)
20.6 30.4 - 12.6 - 9.4 - 7.0 - 9.4 - 74.6
CD(0.05) - 0.21 0.63 - 0.07 - 0.07 - 0.07 - 0.08 - 0.014
32
Maximum moisture content in stones (20.6 %) and kernels (30.4 %) was
found in treatment S4 as compared to the initial moisture content of apricot stones
(7.8 %) and kernels (4.4 %) without soaking of apricot stones (control).
Consequently, the weight of stones and decorticated mass also exhibited increase
from original weight of 20 kg.
Soaking treatments also brought about significant improvement in
geometrical dimensions of apricot kernels, such as length (12.0 to 12.6 mm),
breadth (9.0 to 9.4 mm) and thickness (6.0 to 7.0 mm). Further with the increase
in the moisture content, the geometric mean diameter of kernels also increased
from 8.6 to 9.4 mm. Sphericity, which is a measure to define the shape of kernels
also exhibited increase from 72.1 to 74.6 per cent (Table 4.2). The increase in the
size parameter like geometric mean diameter and sphericity are expected to make
the kernels more rolling on the belt, which will improve their separation from the
shells.
4.1.3 Optimization of treatments for designing mechanical separator for apricot kernels
On the basis of optimized rubber surface and angle of inclination of belt,
the design parameters of mechanical separator for apricot kernels were worked
out. Out of different surfaces, the use of rubberized belt, it’s placement in
inclination position of 22.5o angle from the base and allowing it to move in
opposite direction was optimized. This arrangement allowed rolling of kernels on
the belt and carrying away shells and undecorticated stones to the other end. The
speed of moving belt was optimized at 5 rpm, as increasing the speed of belt
caused mixing of the kernels and shells. The use of hopper with mixing assembly
allowed uniform discharge of the decorticated stone mass on the moving belt for
separation. Forced air draft on the moving belt provided separation of dust
particles as well as directed the flow of the shells towards the upper end for easy
separation (Plate 1). Data in Table 4.3 reveal that soaking of apricot stones or
decorticated stone mass brought about significant improvement in separation of
kernels through mechanical separator.
33
Table 4.3: Effect of soaking treatments on the efficiency of kernel separation in mechanical separator
Treatment*
Particulars
Time taken for separation
(min/kg)
Quantity of kernel separated (kg)
Rate of kernel
separation (Kg/min)
% Separation
1st
Pass 2nd
Pass 3rd
Pass Total in
mechanical separator
4th** Pass
Total
S1 Mechanical decortication without soaking followed by separation in salt solution (control)
0.60 5.80 5.80 0.48 100.0
S2 Soaking of apricot stones in water for overnight followed by decortication and kernel separation in mechanical separator
2.41 1.91 1.36 0.12 3.99 1.72 5.71 0.12 69.9
S3 Soaking of decorticated apricot stones mass in water for overnight followed by kernel separation in mechanical separator
2.50 2.30 1.20 0.12 4.20 1.58 5.78 0.13 72.7
S4 Mechanical decortication of pre-soaked apricot stones followed by further soaking of decorticated stone mass prior to separation in mechanical separator
2.12 2.58 1.34 0.14 4.60 1.25 5.85 0.14 78.6
CD (0.05) 0.06 - - - - - 0.057 0.024 0.19
NOTE: - * 20 kg of stones were used for each batch of experimentation. ** 4 th separation was carried out in 20% salt solution as in control.
34
Out of 20 kg apricot stones, 5.8 kg apricot kernels were obtained by using gravity
separation i.e. dipping decorticated stone mass in 20 per cent salt solution
followed by separation of kernels (control). For separation through mechanical
separator, the stones and decorticated mass after different soaking treatments
were placed in the hopper and allowed to roll on the rubberized belt moving in
the opposite direction. The material was passed through the belt for three times
(three passes). It was evident from the data that maximum separation of kernels
was obtained in first two passes (3.27-3.92 kg) and least (0.12 to 0.14 kg) in the
third pass to achieve complete separation. The left over material was separated by
dipping in salt solution, which was referred to as 4th pass. The soaking treatment
(S4) comprising of decortication of presoaked stones and further soaking of
decorticated stone mass exhibited higher quantity (4.60 kg) of kernels separated
through mechanical separator followed by S3 and S2 treatments. The efficiency of
kernel separation in S4 treatment was found to be 78.6 as against 72.7 per cent
and 69.9 per cent obtained in S3 and S2 treatments. Further, the time taken
(min/kg) for kernel separation through mechanical separator was the lowest in S4
treated stones (2.12 min/kg). Consequently, rate of kernel separation (kg/min)
was highest (0.14 kg/min) as compared to other two treatments. In comparison to
S2 and S3 soaking treatments, the decortication of presoaked stones followed by
further soaking (S4) exhibited highest amount of kernel separation (78.6 %)
through mechanical separator. Soaking of apricot stones prior to decortication
and re-soaking of decorticated mass brought about significant improvement in
kernel separation efficiency and reduced the time taken for separation of kernels
through the mechanical separator. The optimized method for mechanical
separation of kernels consisted of soaking of apricot-stones in water for overnight
followed by soaking of decorticated mass and separation through mechanical
separator having rubberized belt placed on 22.5o inclination for 1 to 3 passes
(Plate 1).
Thus, the mechanical separator can be used for separation of kernels from
mixed stones/ shells/kernel mass after soaking pretreatments of apricot
stones/kernel.
Apricot stones
Soaking in water (Overnight)
Removal of surface moisture
Decortication using mechanical decorticator
Further soaking of decorticated mass for overnight
Removal of surface moisture
Separation in mechanical separator
Fig. 1: Standardization of method for separation of apricot kernels from decorticated mass using mechanical separator
Fig: 3. Effect of pre-treatment on separation efficiency of apricot kernels in mechanical separator
Fig: 4. Effect of pre-treatment of apricot kernels on yield (%) of extracted oil for table oil expeller
100
0
20
40
60
80
100
120
S1
0
5
10
15
20
25
30
35
40
45
50
O1
46
treatment on separation efficiency of apricot kernels in separator
treatment of apricot kernels on yield (%) of extracted oil for
69.972.7
S2 S3 Treatment
O2 O3 O4 O5 O6
3840 41
3942
treatment on separation efficiency of apricot kernels in
treatment of apricot kernels on yield (%) of extracted oil for
78.6
S4
O7
43
35
4.2 Optimization of pretreatments of apricot kernels for improving yield and quality of oil
The effect of soaking of apricot kernels in water (5 and 10 % w/w) with or
without steaming on the yield of kernel oil through Table oil expeller was studied
and compared with oil yield obtained through Soxtec oil extractor using
petroleum ether as organic solvent. The data in Table 4.4 reveal that with the
increase in proportion of water in the kernels, the oil yield exhibited an increase
(40.0 and 41.0 %) at 5 and 10 per cent moisture content. The oil yield through
Table oil expeller from kernels without soaking (control) was found to be 38 per
cent which increased significantly to 40 and 41 per cent when water (5 to 10 %
w/w) was used for soaking of kernels. Further, steaming of kernels prior to oil
extraction brought about significant improvement in oil yield from the steamed
kernels (42.0 and 43.0 %). However, the difference in oil yield between 5 and 10
per cent water soaking was not significant. The press cake left after oil extraction
was proportional to the oil yield from respective treatments. Further, the residual
oil in the press cake ranged between 2.5 to 7.0 per cent with maximum oil
remaining in the press cake left after oil extraction of apricot kernels (7.0%)
without prior soaking and steaming (control). The treatment having minimum
(2.5 %) quantity of residual oil in cake and maximum (43.0 %) quantity of oil
expelled from Table oil expeller was considered optimum and most appropriate.
Thus, soaking of kernel by addition of 10 per cent water followed by steaming
(5 psi) for 15 minutes was considered optimum for achieving higher yield (43.0
%) of expressed oil with minimum (2.5 %) amount of residual oil in the press
cake. The moisture content in the kernels exhibited an expected pattern of
increase with the increase in addition of water content for soaking. However, the
kernels evaluated after steaming showed higher moisture content (13.5 %) than
those without steaming. The extracted oil also showed similar pattern of moisture
content ranging between 0.40 to 1.40 per cent in different treatments (Table 4.4).
However, the difference in oil yield by using 5 per cent or 10 per cent water for
soaking (Treatments O6 and O7) was not significant, as such even soaking of
kernels by using 5 per cent water can be considered appropriate.
36
Table 4.4: Effect of soaking, steaming and oil extraction methods on the yield and quality of apricot oil and press cake
Treatment
Particulars OIL YIELD (%)
PRESS CAKE YIELD
(%)
RESIDUAL OIL IN PRESS CAKE
(%)
MOISTURE
KERNELS (%)
OIL (%)
O1 Oil extraction in Soxtec oil extractor from apricot kernels without adding water
46.0 54.0 - 3.8 -
O2 Oil extraction in Table oil expeller from apricot kernels without adding water (control)
38.0 62.0 7.0 4.0 0.30
O3 Oil extraction in Table oil expeller after soaking by addition of 5% (w/w) water in apricot kernels
40.0 60.0 5.5 4.5 0.38
O4 Oil extraction in Table oil expeller after soaking by addition of 10% (w/w) water in apricot kernels
41.0 59.0 4.5 5.0 0.40
O5 Oil extraction in Table oil expeller after steaming of apricot kernels (5 psi) for 15 min without prior soaking in water
39.0 61.0 6.0 9.0 1.25
O6 Oil extraction in Table oil expeller after soaking by addition of 5% water in apricot kernels followed by steaming (5 psi) for 15 min
42.0 58.0 4.0 12.0 1.30
O7 Oil extraction in Table oil expeller after soaking by addition of 10% water in apricot kernels followed by steaming (5 psi) for 15 min
43.0 57.0 2.5 13.5 1.40
CD(0.05) 1.05 1.34 0.77 0.60 0.03
Wild apricot kernels (5 kg)
Addition of 10 per cent water (50 ml.)
Steaming (5 psi) for 15 min.
Cooling at room temperature to remove surface moisture
Extraction of oil in Table oil expeller
Oil filtration in oil filter press
Storage in coloured bottles for analysis
Fig 2: Standardization of method for extraction of oil from wild apricot kernels through Table oil expeller
37
4.2.1 Effect of pretreatments of apricot kernels on Physico-chemical characteristics of extracted oil
Data in Table 4.5 indicate that the visual colour of extracted oil after
different soaking and steaming treatments remained deep yellow, thus indicating
not much change in visual colour appearance with the use of treatments.
However, according to Tintometer colour evaluation, the yellow colour units in
different oils exhibited a decline (6.4 in control to 5.2 in O7). The oil extracted
after adding water showed lower yellow colour units (5.7) and slightly higher red
(0.3) and blue colour units (0.1). Further, steaming of apricot kernels also caused
decrease in yellow colour units (5.3-5.2) with increase in red (0.6-0.7) and blue
colour units (0.1). Thus, the study indicates that soaking and steaming treatments
did cause some change in colour units as compared to petroleum ether extracted
oil (control). However, broadly, the visual appearance of oil remained deep
yellow in colour.
The apricot kernel oil exhibited low acid value ranging from 2.27 to 2.77
mg KOH/g of oil. The oil extracted from solvent extraction method (O1)
possessed minimum acid value of 2.27 mg KOH/g of oil, while acid value was
found maximum in oil extracted after steaming treatment of kernels (O7). Thus,
extraction of oil in Table oil expeller with or without soaking and steaming
caused some increase in acid value as compared to solvent extracted oil. Iodine
value of apricot oil by using solvent extraction or Table oil expeller with or
without soaking and steaming treatments ranged between 100.2 to 100.6 gI2/100g
thus exhibiting no appreciable effect of different treatment combinations. Iodine
value representing degree of unsaturation of oil being an inherent character is not
expected to change with the method of extraction. Peroxide value representing
the quality of oil ranging between 5.12 to 5.27 meq/kg was affected by the
pretreatment of apricot kernels and method of extraction. Oil extracted through
solvent extraction had the minimum peroxide value (5.12 meq/kg) which
increased significantly to 5.18 meq/kg when the oil was extracted by using Table
oil expeller. Soaking of kernels in 5 to 10 per cent water prior to oil extraction
also caused increase in peroxide value of oil (5.21-5.22 meq/kg). Further,
steaming of kernels with or without soaking also brought some increase in
peroxide value of oil. However, the effect of using 5 or 10 per cent water for
38
Table 4.5: Effect of soaking, steaming and oil extraction methods from apricot kernels on the Tintometer colour units of extracted oil
Treatment Particulars Tintometer colour units (TCU) Visual colour appearance
Yellow Red Blue
O1 Oil extraction in Soxtec oil extractor from apricot kernels without adding water
6.4 0.2 0.0 Deep Yellow
O2 Oil extraction in Table oil expeller from apricot kernels without adding water (control)
5.8 0.4 0.1 Deep Yellow
O3 Oil extraction in Table oil expeller after soaking by addition of 5% (w/w) water in apricot kernels
5.7 0.3 0.1 Deep Yellow
O4 Oil extraction in Table oil expeller after soaking by addition of 10% (w/w) water in apricot kernels
5.7 0.3 0.1 Deep Yellow
O5 Oil extraction in Table oil expeller after steaming of apricot kernels (5 psi) for 15 min without prior soaking in water
5.3 0.6 0.1 Deep Yellow
O6 Oil extraction in Table oil expeller after soaking by addition of 5% water in apricot kernels followed by steaming (5 psi) for 15 min
5.2 0.7 0.1 Deep Yellow
O7 Oil extraction in Table oil expeller after soaking by addition of 10% water in apricot kernels followed by steaming (5 psi) for 15 min
5.2 0.7 0.1 Deep Yellow
39
Table 4.6: Effect of soaking, steaming and oil extraction methods from apricot kernels on the quality characteristics of extracted oil.
Treatment
Particulars
Quality attributes
Acid Value (mg KOH/g)
Iodine Value
(gI2/100g)
Peroxide Value
(meq/kg)
Saponification value
(mg KOH/g)
HCN in oil
(mg/100g)
HCN in press cake
(mg/100g)
Tocopherol content
(µg/g)
O1 Oil extraction in Soxtec oil extractor from apricot kernels without adding water
2.27 100.2 5.12 189.7
0.0
99.8 277.0
O2 Oil extraction in Table oil expeller from apricot kernels without adding water (control)
2.52 100.4 5.18 190.2
26.5
32.5 286.0
O3 Oil extraction in Table oil expeller after soaking by addition of 5% (w/w) water in apricot kernels
2.64 100.4 5.21 190.4
29.2
30.2 286.7
O4 Oil extraction in Table oil expeller after soaking by addition of 10% (w/w) water in apricot kernels
2.67 100.4 5.22 190.6
32.5
28.8 289.0
O5 Oil extraction in Table oil expeller after steaming of apricot kernels (5 psi) for 15 min without prior soaking in water
2.71 100.6 5.24 191.5
0.0
0.0 273.7
O6 Oil extraction in Table oil expeller after soaking by addition of 5% water in apricot kernels followed by steaming (5 psi) for 15 min
2.74 100.6 5.26 191.6
0.0
0.0 272.7
O7 Oil extraction in Table oil expeller after soaking by addition of 10% water in apricot kernels followed by steaming (5 psi) for 15 min
2.77 100.6 5.27 191.7
0.0
0.0 272.0
CD(0.05) 0.016 0.03 0.014 0.13 0.20 0.17 1.64
40
soaking was found non-significant with respect to its peroxide value.
Saponification value of apricot oil extracted by using solvent extraction or Table
oil expeller with or without soaking and steaming treatments ranged between
189.7 to 191.7 mg KOH/g. Statistically, though the difference in values were
significant between solvent extraction (control) and table oil expelled oil yet the
difference within soaking and steaming were not appreciable. Thus, the
saponification value was not affected much with the pretreatment of apricot
kernels. HCN content in the oil was also variable in different treatments. The use
of different pretreatments of apricot kernels brought about change in presence of
hydro-cyanic acid (HCN) in the extracted oil. Oil extracted through Soxtec oil
extraction apparatus did not show the presence of HCN while press cake left after
oil extraction exhibited highest content (99.8 mg/100g) of HCN. Similarly, in
case of oil extracted through Table oil expeller, the level of HCN content varied
according to the type of treatments used for oil extraction. Oil and press cake
obtained after steaming of kernels at 5 psi for 15 min did not show any presence
of HCN. While, the oil extracted through Table oil expeller after soaking of
kernels without steaming showed the presence of HCN. The HCN content in oil
and press cake from un-soaked kernels was 26.5 and 32.5 mg HCN/100 g
respectively and kernels soaked by using 5 and 10 per cent water exhibited 29.2
and 32.5 mg HCN/100g in oil and 30.2 and 28.8 mg HCN/100g in press cake
respectively (Table 4.6). Thus, steaming of kernels prior to oil extraction through
Table oil expeller was effective in removing the HCN content from oil as well as
press cake. The vitamin E content in oils ranged between 272 to 289 µg/g in oil
obtained from kernels after using different pre-treatments. Maximum tocopherol
content (289.0 µg/g) was found in oil obtained from expelling of pre-soaked
kernels in 10 per cent water (O4). As expected, steaming of kernels caused some
loss in vitamin E content of the extracted oil. Thus, on the basis of complete
removal of HCN content and minute changes in quality attribute of oil, the
extraction of oil through Table oil expeller after soaking and steaming of kernels
was found optimum for apricot oil extraction.
Fig: 5 Effect of pre-treatment of apricot kernels on the HCN content (mg/100g) of extracted oil and press cake
Fig: 6. Effect of pre-treatment of apricot kernels on the tocopherol content (µg/g) of extracted oil
0
26.5 29.232.5
0 0 0
99.8
32.5 30.2 28.8
0 0 00
20
40
60
80
100
120
O1 O2 O3 O4 O5 O6 O7
HCN in oil (mg/100g) HCN in press cake (mg/100g)
277
286 286.7
289
273.7272.7 272
260
265
270
275
280
285
290
295
O1 O2 O3 O4 O5 O6 O7
41
4.2.2 Effect of pretreatment of apricot kernels on the Fatty acid composition (% w/w) of extracted oil
Data presented in Table 4.7 indicate that apricot oil irrespective of
pretreatments and methods of extraction contained appreciable proportion of
unsaturated fatty acids (90.48-91.52 % w/w) as compared to only (8.61-8.87 %
w/w) saturated fatty acids. Among unsaturated fatty acids, monounsaturates
comprising of palmitoleic acid (C16:1) and oleic acid (C18:1) accounted for 62.34
to 64.79 per cent (w/w) in apricot oil from different treatments. Oleic acid (C18:1)
was the predominant monounsaturated fatty acid in the apricot oil (61.93-64.16 %
w/w). The oil was found to be good source of poly-unsaturated fatty acids
comprising of 25.66 to 27.61 per cent (w/w) linoleic acid (C18:2) and 1.02 to 1.47
per cent (w/w) linolenic acid (C18:3). The soaking and steaming treatments of
apricot kernels followed by oil extraction through Table oil expeller did cause
some change in the fatty acid composition of extracted oil. Among the oil
extracted through Table oil expeller (O2-O7), the level of palmitic acid (7.82-7.84
% w/w), palmitoleic acid (0.52-0.58 % w/w), stearic acid (0.97-1.03 % w/w) and
oleic acid (63.13-63.18 % w/w) was higher in oil extracted after soaking and
steaming of kernels (O5-O7 treatments). Thus, soaking and steaming of apricot
kernels prior to oil extraction was considered appropriate for extraction of oil
through Table oil expeller.
4.3 Standardization of method for utilization of apricot kernel press cake for extraction of volatile oil
The method for recovery of volatile oil from press cake left after oil extraction
from apricot kernel was standardized. On the basis of preliminary screening
dilution of press cake in water in 1:10 proportion was found most appropriate and
used for hydro-distillation in 10 litre capacity distillation apparatus. Further, out
of different fractions of distillate (100 ml, 200 ml, 300 ml, 400 ml and 500 ml)
collected from 10 litres of diluted press cake, it was found that maximum volatile
oil fragrance was found only in the first 100 ml distillate and used for further
experimentation. Data in table 4.8 reveal that 1.0 per cent distillate from 10 litres
of diluted press cake (1:10) contains 12 per cent benzaldehyde (Table 4.8).
42
Table 4.7: Effect of soaking, steaming and oil extraction methods from apricot kernels on the Fatty acid composition (% w/w) of extracted oil
Σ SFA - Sum of Saturated fatty acid Σ MUFA - Sum of Monounsaturated fatty acid Σ PUFA - Sum of Polyunsaturated fatty acid Σ UFA - Sum of Unsaturated fatty acid U:S Ratio - Unsaturated:Saturated ratio O1-O7 - Details of soaking, steaming and oil extraction methods shown in Table-2 (Chapter-3)
Sr. No. Fatty Acid Soaking, steaming and oil extraction method CD(0.05)
O1 O2 O3 O4 O5 O6 O7 1 Palmitic C16:0 7.61 7.69 7.70 7.73 7.82 7.83 7.84 0.012 2 Palmitoleic C16:1 0.63 0.41 0.42 0.46 0.52 0.56 0.58 0.013 3 Stearic C18:0
1.14 0.92 0.92 0.95 0.97 0.97 1.03 0.014 4 Oleic C18:1
64.16 61.93 61.95 61.97 63.13 63.17 63.18 0.030 5 Linoleic C18:2
25.66 27.71 27.65 26.63 26.55 26.51 26.49 0.021 6 Linolenic C18:3
1.02 1.47 1.45 1.42 1.16 1.15 1.12 0.015 7777
Σ SFA (1+3) 8.75 8.61 8.62 8.68 8.79 8.79 8.87 -
8888 Σ MUFA (2+4)
64.79 62.34 62.37 62.43 63.65 63.73 63.76 -
9999 Σ PUFA (5+6)
26.68 29.18 29.10 28.05 27.71 27.66 27.61 -
10101010 Σ UFA (2+4+5+6)
91.47 91.52 91.47 90.48 91.36 91.39 91.37 -
U:S Ratio (10/7) 10.45:1 10.63:1 10.61:1 10.42:1 10.39:1 10.39:1 10.30:1 -
43
Allowing the diluted press cake to macerate at 50 oC for overnight (T2) increased
the yield of benzaldehyde to 17.0 per cent in the first 100 ml distillate of
fractions. However, volatile oil also contained hydrocyanic acid (45.0 to 51.2
mg/100g) which is an undesirable. Data in Table 4.8 further indicate that re-
distillation of distillate up to 50 per cent of original volume in the laboratory
scale Clevenger’s apparatus resulted in appreciable improvement in benzaldehyde
content of the volatile oil. The benzaldehyde content increased after re-distillation
of distillate in treatments, T3 and T4 to 26.7 and 29.8 per cent from initial
concentration of 12.0 to 17.0 per cent.
Table 4.8: Standardization of method for extraction of hydro- distillate/volatile oil from apricot kernel press cake
Treatment Particulars Volatile oil yield
(ml)
Benzaldehyde (%)
Residual HCN (mg/100 ml)
Specific gravity of Volatile oil
T1 Diluting press cake with water (1:10) followed by distillation to collect 1 % distillate (100 ml)
100.0 (1.0%)*
12.0 45.0 1.042
T2 Diluting press cake with water (1:10) maceration at 50 °C for 12 hours followed by distillation to collect 1 % distillate (100 ml)
100.0 (1.0%)*
17.0 51.2 1.042
T3 Re-distillation of distillate (100 ml) from T1 with 3% each of CaO and FeSO4 to collect 50 % of volatile oil
50.0 (50%)*
*
26.7 0 1.045
T4 Re-distillation of distillate (100 ml) from T2 with 3% each of CaO and FeSO4 to collect 50 % of volatile oil
50.0 (50%)*
*
29.8 0 1.046
CD (0.05) 0.35 0.27 0.002
* Figure represents per cent of volatile oil obtained from distillation of total volume (10 litre)
** Figure represents per cent of volatile oil obtained after re-distillation of distillate T1 & T2 - 10 litre of diluted press cake (1:10) was used for distillation in
commercial distillation unit T3 & T4 - 100 ml of distillate was re-distilled in Clevenger’s apparatus
The highest concentration of benzaldehyde (29.8 %) was found in distillate
obtained after maceration of diluted press cake for 12 hours followed by mixing
of 3 per cent each of CaO and FeSO4 prior to re-distillation (T4). Further, addition
44
of 3 per cent (w/v) each of CaO and FeSO4 caused complete removal of residual
HCN in the re-distilled volatile oil. The volatile oil exhibited a specific gravity of
1.042 to 1.046. Thus, collection of 1 per cent distillate from the diluted press cake
(1:10) obtained after maceration (at 50 oC for 12 hours) and further collection of
50 per cent fraction (v/v) after re-distillation of distillate containing 3 per cent
each of CaO and FeSO4 was optimized for extraction of volatile oil from the
apricot press cake.
4.3.1 Anti-fungal activity of apricot volatile oil
Suitability of volatile oil from apricot kernel press cake was evaluated for
use as antimicrobial agent against different plant pathogenic fungi. Mycelial
growth rate of different plant pathogenic fungi was assayed by Poisoned Food
Technique in presence of different concentration of volatile oil to evaluate the in-
vitro fungicidal effect. Data in Table 4.9 indicate mycelial growth rate (mm/day)
of different plant pathogenic fungi as affected by different concentration of
volatile oil from apricot kernel press cake. The mycelial growth of Fusarium sp.,
Sclerotium sp. and Macrophomina sp. was recorded as 9.7, 9.0 and 9.8 mm/day
with mean value of 9.5 mm/day in control medium having no volatile oil. Use of
different concentration of volatile oil from apricot kernel press cake (5-20 %)
brought about significant effect on the mycelia growth rate of different fungi.
Table 4.9: Effect of different concentrations (%) of apricot press cake volatile oil on the mycelial growth rate of some plant pathogenic fungi
Volatile oil Concentration
(%)
Average mycelial growth (mm/day) Fusarium
sp. Sclerotium
sp. Macrophomina
sp. Mean
0.0 %
9.7 (18.1)
9.0 (17.5)
9.8 (18.2)
9.5 (17.9)
5.0 %
8.4 (16.8)
5.5 (13.6)
6.1 (14.3)
6.6 (14.9)
10.0 %
0.0 (0.0)
1.0 (5.7)
1.3 (6.5)
0.7 (4.1)
15.0 % 0.0 0.0 0.0 0.0 20.0 % 0.0 0.0 0.0 0.0 CD(0.05) 0.08 0.27 0.13 -
Values in parentheses indicate transformed values.
Left over press cake after oil extraction (1 kg)
Addition of water (10 kg)
Maceration at 50 oC for 12 hrs
Water distillation in volatile oil extraction apparatus
Collection of volatile oil (100 ml)
Addition of 3% each CaO and FeSO4
Re-distillation of distillate in Clevenger’s apparatus
Collection of volatile oil (50 ml) without HCN
Fig 3: Standardization of method for extraction of apricot volatile oil from left over press cake
Fig: 7. Benzaldehyde content of volatile oil from apricot kernel press cake
12
17
26.7
29.8
0
5
10
15
20
25
30
35
T1 T2 T3 T4
Benzaldehyde (%)
45
The mean growth rate (mm/day) at 5 per cent volatile oil concentration was found
to be 8.4 mm/day in Fusarium sp., 5.5 mm/day in Sclerotium sp. and 6.1 mm/day
in Macrophomina sp. While at 10 per cent volatile oil concentration the growth
rate was significantly reduced to 0.0 mm/day in Fusarium sp., 1.0 mm/day in
Sclerotium sp. and 1.3 mm/day in Macrophomina sp. Mycelial growth rate in
volatile oil concentration to be going 10 per cent i.e. 15 to 20 per cent was
recorded to be 0.0 mm/day. Statistically, the difference in growth rate at different
concentration of volatile oil found to be significant.
Further, it was revealed from the data (Table 4.10) that use of volatile oil
from apricot press cake exhibited a significant inhibitory effect on the mycelia
growth of different plant pathogenic fungi. Even 10 per cent concentration of
volatile oil was effective in bringing about 100 per cent inhibition in mycelia
growth of Fusarium sp. followed by 83.5 per cent in Macrophomina sp. and
98.06 per cent in Sclerotium sp. However, 100 per cent inhibition in mycelial
growth of all the three plant pathogenic fungi was observed when 15 per cent and
20 per cent concentration of volatile oil was used. Thus, it can be concluded that
15 per cent concentration of apricot press cake volatile oil can significantly be
used for inhibiting growth of Fusarium, Sclerotium and Macrophomina fungi.
The antifungal property of volatile oil of apricot press cake could be a potential
source of new antifungal agent and can be used as natural antifungal agent for
treatment of various skin diseases as well as for control of plant pathogenic fungi.
Table 4.10: Inhibitory effect of apricot press cake volatile oil against some plant pathogenic fungi
* Mycelial growth inhibition was measured after 7 days of incubation. Growth inhibition
was measured by using different concentration of apricot press cake volatile oil. Values in parentheses indicate transformed values.
Fungus sp.
Mycelial growth inhibition (%) at different concent rations after 7 days
5% 10% 15% 20% Fusarium sp. 31.8
(34.3) 100
(90.0) 100 100
Sclerotium sp. 61.4 (51.6)
83.5 (66.0)
100 100
Macrophomina sp. 52.44 (46.4)
98.06 (82.0)
100 100
CD (0.05) 0.07 0.10 - -
CHAPTER–5
DISCUSSSION
The present investigation entitled “Refinement of technology for
extraction and utilization of apricot kernel oil and press cake” was conducted in
the Department of Food Science and Technology, Dr. Y S Parmar University of
Horticulture and Forestry, Nauni, Solan, (H.P.) during the years 2010-2013. The
result of this study presented in tables 4.1-4.10 are discussed as under:
5.1 Development of method for mechanical separation of apricot kernels after decortication
The parameters like angle of static friction of apricot stones and kernels
on different surfaces of rolling belt and effect of soaking of kernels on size
parameters of kernels were standardize to design a mechanical separator for
separation of kernels from the decorticated apricot stone mass.
5.1.1 Optimization of coefficient of static friction
Angle of static friction (θ) of un-soaked and soaked wild apricot stones,
kernels, shells and decorticated mass (shells+kernels) was evaluated on four
surfaces viz. wood, glass, paper and rubber. On different surfaces, the angle of
static friction of apricot stones and kernels was found to be 20.0 to 22.8o on
wood, 9.6 to 14.0o on glass, 13.8 to 16.8o on paper and 22.2 to 25.3o on rubber
surface (Table 4.1). It was clear that the angle of static friction for all fractions of
apricot stones after soaking was more than the un-soaked stones. Soaking of
apricot stones brought about significant improvement on the angle of static
friction of stones and kernels. Earlier, Fathollahzadeh et al. (2008) also found
increase in angle of static friction on wood, fiberglass, glass and galvanize sheet
with the increase in moisture content of the apricot stones as well as kernels. The
mean value of soaked kernels was recorded as 21.0o on wood, 10.2o on glass,
14.5o on paper and 22.5o on rubber against 19.0o on wood, 9.0o on glass, 13.0o on
paper and 22.0o on rubber in un-soaked material. Similar to these findings,
Ahmadi et al. (2009) recorded lower angle of static friction on glass for apricot
shells and kernels as compared to wood, galvanize sheet and fiberglass sheet.
47
Jafari et al. (2011) also observed increase in angle of static friction of sunflower
seed with increase in moisture content from 5 to 25 per cent on mild and
galvanized steel sheet. Therefore, soaking of apricot stones and kernels prior to
separation was considered optimum. Further, in view of flexibility and static
friction, the use of rubberized belt with an inclination angle of 22.5o from base
was found appropriate for the mechanical separator. Thus, at 22.5o inclination
angle of the rubberized belt it was expected to allow the kernels to roll down on
opposite upward moving belt thereby separating kernels from the crushed stone
mass (kernels, shells and undecorticated stones).
5.1.2 Effect of soaking treatments on moisture and size parameter of apricot stones and kernels
As expected soaking thought about increase in moisture and size
parameters of the apricot stones and kernels (Table 4.2). Soaking of apricot
stones for overnight followed by re-soaking after decortication caused increase in
moisture content from 7.8 per cent to 20.6 per cent in stones and 4.4 per cent to
30.4 per cent in kernels. Initial moisture content was 7.8 per cent in stones and
4.4 per cent in kernels without soaking (control). Due to inhibition of moisture,
the size parameters like length, breadth, thickness, geometric mean diameter and
sphericity of stones and kernels also increased. The length of stones and kernels
before soaking (Control) was 20.0 mm and 12.0 mm which were found to
increase to 20.5 mm and 12.6 mm respectively after soaking treatment. Further,
the breadth of stones (15.9 mm) and kernels (9.0 mm) before soaking increased to
16.4 mm and 9.4 mm respectively after soaking. Thickness of stones and kernels
before soaking was 10.3 mm and 6.0 mm which increased to 10.6 mm and 7.0
mm after soaking respectively. With increase in length, breadth and thickness the
geometric mean diameter of stones and kernels after soaking was found as 15.3
mm and 9.4 mm respectively from initial value of 14.8 mm and 8.6 mm
respectively before soaking. Consiquently, with the increase in various size
parameters the sphericity of kernels also increased to 74.6 per cent after soaking
from the initial value of 72.1 per cent before soaking. The improvement in size
parameters of soaked apricot kernels was attributed to cellular inflation and
penetration of water in the porous area of kernels. In conformation to these
48
studies, Haciseferogullari et al. (2007) also found improvement in technological
properties of apricot fruits like length, diameter, geometric mean diameter,
sphericity, bulk density and static coefficient of friction with increase in moisture
contents.
Fathollahzadeh et al. (2010) recorded increase in sphericity of apricot
kernels from 62.2 to 62.9 per cent with increase in moisture content from 2.86 to
13.03 per cent.
Jafari et al. (2011) also found increase in surface area of sunflower seeds
of Shamshiri variety with the increase in moisture from 6.3 to 20 per cent.
Improvement in size parameters of kernels like length, breadth, thickness,
geometric mean diameter and sphericity after soaking are expected to make the
kernels more rolling on the upward moving rubberized belt, which will improve
their separation from the shells. Thus, soaking of apricot stones for overnight
followed by re-soaking after decortication was optimized for improving the size
parameters of apricot kernels to help in their separation through the mechanical
separator.
5.1.3 Mechanical separator for apricot kernels
Keeping in view the optimized rubber surface for allowing rolling, angle
of inclination of belt and improvement in physical properties of stones and
kernels by soaking, the mechanical separator for separation of apricot kernels was
developed. Out of different surfaces, the use of rubberized belt and it’s placement
in inclination position of 22.5o angle from the base was found optimum allowing
it to move in opposite direction. This arrangement allowed rolling of kernels to
lower end on the belt and carrying away shells and undecorticated stones to the
upper end. The speed of movement of belt on the mechanical separator was
optimized at 5 rpm, as increasing the speed of belt caused mixing of the kernels
as well as shells. The use of hopper with mixing assembly allowed uniform
discharge of the decorticated stone mass on the moving belt for separation.
Forced air draft on the moving belt provided separation of dust particles as well
as directed the flow of the shells towards the upper end for easy separation (Plate
1). Further, soaking of apricot stones followed by re-soaking of decorticated
stone mass significantly improved the separation of kernels.
49
Though, separation of kernels by dipping in 20 per cent salt solution
(gravity separation) yielded 5.8 kg kernels from 20 kg decorticated stone mass,
considered as complete separation. Yet, the kernels are known to absorb salt,
which is not considered appropriate for oil extraction purposes. Thus, mechanical
method was standardized for kernels separation.
For separation through mechanical separator, the stones and decorticated
mass after different soaking treatments were placed in the hopper and allowed to
roll on the rubberized belt moving in the opposite direction. The material was
passed through the belt for three times (three passes). It was evident from the data
that maximum separation of kernels was obtained in first two passes (3.27-3.92
kg) and least (0.12 to 0.14 kg) in the third pass to achieve complete separation.
The left over material was separated by dipping in salt solution, which was
referred to as 4th pass. The soaking treatment comprising of decortication of pre-
soaked stones and further soaking of decorticated stone mass (S4) exhibited
higher quantity (4.60 kg) of kernels separated through mechanical separator
followed by other two treatments viz. soaking of apricot stones prior to
decortications (S2) or soaking of decorticated stone mass (S3). The efficiency of
kernel separation in S4 treatment was found to be 78.6 as against 72.7 per cent
and 69.9 per cent obtained in S3 and S2 treatments. The increase in separation
efficiency was alternated to the improvement in size parameters of the kernels
viz. sphericity, geometric mean diameter, etc. which allow the kernels to roll on
the surface. Further, the time taken (min/kg) for kernel separation through
mechanical separator was the lowest in S4 treated stones (2.12 min/kg).
Consequently, rate of kernel separation (kg/min) was highest (0.14 kg/min) as
compared to other two treatments. Thus, mechanical separator can be used
successfully for separation of about 78.6 per cent kernels from decorticated
apricot stones to replace the use of gravity separation using salt solution.
Therefore, the optimized method for mechanical separation of kernels consisted
of soaking of apricot stones in water for overnight followed by re-soaking of
decorticated mass and separation through mechanical separator having rubberized
belt placed on 22.5o inclination for 1 to 3 passes was considered most
appropriate.
50
5.2 Optimization of parameters of apricot kernel for improving yield and quality of oil
Pre-treatment of apricot kernels like soaking in water with or without
steaming was evaluated for improving yield and quality of oil through Table oil
expeller. Out of different considerations, soaking of apricot kernels in 5-10 per
cent water followed by steaming (5 psi) for 15 minutes prior to oil extraction in
Table oil expeller brought about significant improvement in oil yield (43 %) as
compared to only 38 per cent oil found in untreated kernels. However, soaking
alone also caused increase in extracted oil (40-41 %) than without soaking but the
yield was lower than the oil extracted after soaking and steaming of kernels. The
residual oil in press cake left after oil extraction was found to be minimum (2.5
%) as compared to the other treatments. In conformation to these results Gupta
and Sharma (2009) recorded only 39-40 per cent oil in apricot kernels, extracted
without using pre-treatments. Sharma et al. (2005) obtained 43.03 per cent in
wild apricot kernels (chulli). The increase in oil recovery thought be attributed to
the releasing of oil from the oil bearing cells caused by soaking and steaming of
the kernels. Oil extracted through Table oil expeller (43 %) and oil actually
present in kernels (46 %) obtained by solvent extraction indicate that soaking and
steaming pre-treatments were capable to extract about 91.30-93.48 per cent oil
from kernels through Table oil expeller. Thus, soaking of kernels by addition of
10 per cent water followed by steaming at 5 psi for 15 minutes was optimized for
extracting higher oil yield (43 %) through Table oil expeller with minimum
amount of residual oil (2.5 %) in the press cake.
5.2.1 Physico-chemical characteristics of apricot kernel oil
The visual appearance of apricot oil extracted from kernels with or
without soaking and steaming treatments recorded deep yellow, thus indicating
not much change in appearance with the use of pre-treatments. Earlier, Sharma et
al. (2005), Gupta (2006) and Tilakaratne (2007) also observed visual yellow
colour in kernel oil from different apricot cultivars and in wild apricot kernel oil.
The tintometer colour units (TCU) also reflected yellowness as predominant
colour which ranged from 5.2 to 6.4 (TCU) in different treatments. Gupta (2006)
51
recorded yellow colour ranging between 5.7-6.9 TCU in apricot kernel oil from
different cultivars from different areas of Himachal Pradesh. Tilakaratne (2007)
recorded 6.8 TCU in bitter kernel oil and 5.7 TCU in sweet kernel oil. However,
soaking and steaming of kernels did cause some decrease in yellow colour units
and slightly higher red and blue colour units in the extracted oil. However,
broadly the visual appearance of oil was deep yellow and acceptable.
The acid value represents the amount of free fatty acid present in the oil
which is also used as an indicator of hydrolytic rancidity. The wild apricot kernel
oil after different pre-treatments exhibited low acid value (2.27 to 2.77 mg
KOH/g oil). Sharma et al. (2005) reported acid value ranging between 2.26-4.31
mg KOH/g oil in apricot kernel oil. Gupta (2006) and Tilakaratne (2007) also
recorded low acid value (2.27 to 2.78 mg KOH/g oil) and (2.28 mg KOH/g oil),
respectively. While Gupta (2006) recorded high acid value in sweet kernelled
apricot oil ranged between 4.27 to 4.35 mg KOH/g oil. According to FSSA
(2006) the acid value of oil shall not exceed 6.0 mg KOH/g oil. Therefore, the
acid value of apricot kernel oil obtained after soaking and steaming of kernels
was found well below the specified limit.
Iodine value defined as number of grams of iodine absorbed by 100 g of
the oil represents the degree of unsaturation in the oil. More the iodine value
more will be the unsaturation. The iodine value of oil extracted from apricot
kernel after different pre-treatments was ranged between 100.2 to 100.6 gI2/100 g
oil. Earlier, Gupta (2006) recorded iodine value in sweet and bitter apricot kernel
oils, ranging between 100.2 to 112.7 gI2/100 g oil. Tilakaratne (2007) also
observed the iodine value ranging between 100.3 to 110.4 gI2/100 g oil in apricot
kernel oil. Further, commercially sold refined, bleached and deodorized (RBD)
apricot oil also contained iodine value within the range of 100 to 112 gI2/100g
(Anonymous, 20012a). Therefore, the iodine value of oil obtained after soaking
and steaming of apricot kernels remained within the specified limit for apricot oil.
The peroxide value of apricot oil obtained after different pre-treatments of
kernels varied between 5.12 to 5.27 meq/kg oil. Similar to these results,
Tilakaratne (2007) recorded peroxide value of 5.28 meq/kg oil and 4.3 meq/kg oil
in bitter and sweet kernelled apricot oil. Gupta (2006) found peroxide value in
52
range of 5.12 to 5.26 meq/kg oil in bitter kernelled oil and 4.32 to 4.40 meq/kg in
sweet kernelled oil. However, soaking of apricot kernels followed by steaming
caused some increase in peroxide value. The level of peroxide value was found
well below the critical value of peroxides (125 meq/kg) specified for unsaturated
fatty acids (Jacobs, 1958). The commercially sold refined, bleached and
deodorized (RBD) apricot kernel oil was reported to have peroxide value of 8 to
10 meq/kg oil (Anonymous, 20012a). Therefore, soaking and steaming of apricot
kernels did not cause any adverse effect on the peroxide value of the extracted
oil.
Further, the saponification value of apricot kernel oil extracted by using
Solvent extraction or Table oil expeller with or without soaking and steaming
pre-treatments ranged between 189.7 to 191.7 mg KOH/g oil. Thus, in view of
the range of saponification value, the soaking and steaming did not cause any
adverse effect on the quality of the oil. Earlier, Tilakaratne (2007) and Gupta
(2006) recorded saponification values as 190.3 mg KOH/g oil and 189.8 mg
KOH/g oil in bitter and 190.3 mg KOH/g oil in sweet kernel oil, respectively.
According to FSSA, 2006 (Food Safety and Standard Act), the saponification
value of almond oil should be in the range of 186 to 195 mg KOH/g oil
(Anonymous, 2012a). Thus, the saponification value of the oil extracted after
soaking and steaming of apricot kernels remained well within the specified limit
of almond oil.
Wild apricot kernels are known to contain cyanogenic glucoside-
amygdalin which upon hydrolysis in presence of β-glucosidase yield hydrocyanic
acid (HCN) and cause bitterness in the kernels (Cheeke, 1998). Sharma et al.
(2005) recorded a value of 72 mg/100g in wild apricot kernels. However, oil
extracted from the apricot kernel contains comparatively very less value of the
bittering compounds on HCN is reported to be water soluble. In the present
investigations, oil and press cake obtained after passing the un-soaked apricot
kernels through Table oil expeller showed the presence of 26.5 and 32.5 mg
HCN/100g respectively. Soaking of kernels in 5-10 per cent water prior to oil
extraction through Table oil expeller exhibited increased level of HCN in oil
(29.2-30.2 mg/100g) and press cake (28.8-32.5 mg/100g). Increased level of
53
HCN in soaked apricot kernel oil was attributed the activation of inherent β-
glucosidase enzyme in the soaked kernels to cause hydrolysis of amygdalin to
release HCN. However, the oil extracted through solvent extraction did not show
the presence of HCN in oil while, press cake contained as high as 99.8 mg/100g
which was attributable to the volatile nature of HCN thus remaining only in the
press cake. Further, oil and press cake obtained after steaming of kernels at 5 psi
steam pressure for 15 minutes were completely free of HCN. This might be
attributed to the loss of HCN by steaming as HCN is reported to be water soluble.
Thus, steaming of apricot kernels can be considered a necessary pre-treatment for
extraction of oil which is completely free of bittering component (HCN).
Tocopherol (vitamin E) content in apricot kernel oil varied between 272.0
to 289.0 µg/g. Different workers found different levels of tocopherol in different
cultivar of apricot kernel oil. Tilakaratne (2007) reported the tocopherol content
varied between 430 to 438 µg/g in bitter and sweet kernelled apricot oil. Earlier,
Dutta et al. (1999) recorded the tocopherol content in apricot oil in the range of
268.5 to 436.0 µg/g. As expected, steaming of kernels caused some loss in
vitamin E content of the oil.
On the basis of physico-chemical characteristics and complete removal of
HCN in the oil method consisting of soaking apricot kernels in 5 to 10 per cent
water followed by steaming (5 psi) for 15 minutes prior to oil extraction through
Table oil expeller was found most appropriate.
5.2.2 Effect of pre-treatment of apricot kernels on the Fatty acid composition (% w/w) of extracted oil
The fatty acid present in the apricot kernel oil (Table 4.6) were found to
be as palmitic (7.61 to 7.84 %), palmitoleic (0.41 to 0.63 %), stearic (0.92 to 1.14
%), oleic (61.93 to 64.16 %), linoleic (25.66 to 27.71 %) and linolenic acid (1.02
to 1.47 %). It was found that apricot kernel oil irrespective of pre-treatments and
method of extraction possessed an appreciable proportion of unsaturated fatty
acid which comprised of 62.34 to 64.79 per cent monounsaturated fatty acid and
26.68 to 29.18 per cent polyunsaturated fatty acid. While saturates were only
ranging from 8.61-8.87 per cent thus the ratio between unsaturates and saturates
(U/S) was ranging from 10.45 to 10.63. Among the unsaturated fatty acids, oleic
54
acid (C18:1) and linoleic acid (C18:2) were the predominant acids in apricot kernel
oil. Soaking and steaming treatments of apricot kernels followed by oil extraction
through Table oil expeller did cause some changes in the fatty acid composition
of extracted oil. However, the ranges of fatty acids in the present investigation
were in agreement with earlier workers.
Tilakaratne (2007) recorded a value of 62.07 per cent oleic acid and 27.76
per cent linoleic acid in apricot kernel oil. Sherin et al. (1994) recorded a value of
68.88 per cent oleic acid and 15.77 per cent linoleic acid in kernel oil of NJA-13
apricot cultivar grown in Pakistan. According to Kapoor et al. (1987) the oleic
and linoleic acid content of different cultivars of apricot grown in Ladakh region
ranged between 50.95-83.33 per cent and 9.62-45.90 per cent respectively.
Similarly, kernel oil from Amar cultivar of apricot grown in Egypt was reported
to contain 66.29 per cent and 28.64 per cent of oleic and linoleic acid respectively
(Abd El-Aal et al. 1986). In wild apricot kernel oil presence of oleic and linoleic
acid was found 74.3 per cent and 21.6 per cent respectively (Aggarwal et al.
1974). The oil rich in polyunsaturated fatty acid have been shown to reduce the
risk of cardio vascular disease (Agar et al. 1995). Linoleic and linolenic acid are
essential fatty acids and are important for maintenance of skin, hair growth,
regulation of cholesterol metabolism and maintenance of cell integrity (Sardesai,
1997). Therefore, apricot kernel oil possesses special dietary importance and can
be used for edible and pharmaceutical purpose.
Thus, a method consisting of soaking (5-10 %) and steaming (5 psi, 15
min.) of apricot kernels prior to oil extraction in Table oil expeller resulting in
higher oil yield with no adverse effect on the quality and completely free from
HCN was optimized for apricot oil extraction at commercial scale.
5.3 Method for extraction and utilization of volatile oil from apricot kernel press cake
5.3.1 Standardization of method for extraction of volatile oil from apricot kernel press cake
Process protocol for extraction of volatile oil from press cake left after
expelling of apricot kernel oil through Table oil expeller was standardized.
Process optimization consisted of standardization of pre-treatment of press cake
55
slurry to allow maximum hydrolysis of inherent amygdalin to benzaldehyde and
HCN, collection of appropriate proportion of distillate having volatile oil and
removal of HCN from the distillate. On the basis of preliminary screening, the
dilution of press cake in water in 1:10 proportion was found appropriate for use
in distillation as lower dilution resulted in slurry of very thick consistency and
most suitable for distillation purpose. Out of different fractions of distillate (100
ml, 200 ml, 300 ml, 400 ml and 500 ml) obtained from distillation of press cake
slurry, collection of first 100 ml (1 % of slurry) contained the maximum volatile
oil with 12 per cent benzaldehyde (T1). Allowing the diluted press cake slurry to
macerate at 50 oC for overnight (T2) followed by distillation caused increase in
benzaldehyde to 17 per cent is in first 100 ml distillate (Table 4.8). However, the
distillate also contained hydrocyanic acid (45.0-51.2 mg/100g) which is an
undesirable component in the volatile oil. This increase in benzaldehyde along
with HCN in distillate upon maceration of slurry was attributable to the activation
of amulsin (an inherent β-glucosidase enzyme) known to be present in the press
cake slurry, which react upon the amygdalin during maceration and released
benzaldehyed, HCN and glucose (Liener, 1966). Therefore, first distillate
contained both benzaldehyde as well as HCN. Re-distillation of distillate up to
first 50 per cent of original volume in Clevenger’s apparatus was found
appropriate in increasing the concentration of benzaldehyde in the distillate (T3)
to 26.7 to 29.8 per cent (T3 & T4) from initial concentration of 12 to 17 per cent.
As expected the highest concentarion of benzaldehyde (29.8 %) with no residual
HCN was found in the distillate obtained after maceration of diluted press cake
for 12 hours followed by mixing of 3 per cent each of FeSO4 and CaO prior to re-
distillation (T4). According to Gildmeister and Holfmann (1974) the addition of 3
per cent (w/v) each of FeSO4 and CaO in the distillate caused precipitation of
HCN as insoluble calcium ferro-cyanide, thereby making the re-distilled volatile
oil completely free of HCN.
In conformation to these results, Tilakaratne (2007) reported that re-
distilling of 3.31 per cent volatile oil after addition of CaO and FeSO4 in distillate
contained as high as 89.0 per cent benzaldehyde without any HCN. Gildmeister
and Holfmann (1974) also recorded 0.5 to 0.7 per cent volatile oil from bitter
56
almond and 0.6 to 1.8 per cent from apricot kernels. Thus, the method consisting
of maceration of press cake slurry (1:10) at 50 oC for overnight followed by
distillation of 10 litres slurry in volatile oil distillation apparatus to collect 1 per
cent distillate and re-distillation of distillate in Clevenger’s apparatus (50 %) after
addition of 3 per cent each of FeSO4 and CaO was optimized to obtain volatile oil
completely free of HCN for use as flavourant.
5.3.1 Antifungal activity of apricot volatile oil
The volatile oil obtained after hydro-distillation of macerated apricot
kernels press cake slurry (1:10) for overnight at 50 oC was evaluated for anti-
microbial properties. It was found that volatile oil considerably checked the
mycelial growth rate (mm/day) of different fungi. The initial mycelial growth rate
of Fusarium sp. (9.7 mm/day), Sclerotium sp. (9.0 mm/day) and Macrophomina
sp. (9.4 mm/day) without use of volatile oil (Control) was reduced to 8.4 mm/day
(Fusarium sp.), 5.5 mm/day (Sclerotium sp.) and 6.8 mm/day (Macrophomina
sp.) when 5 per cent volatile oil was used in the growing medium. Significant
reduction in mycelial growth rate ranging between 0.0-1.3 mm/day was observed
when 10 per cent volatile oil was used while use of volatile oil beyond 10 per
cent brought about complete check in the mycelial growth (Table 4.9). In view of
statistically insignificant difference in 15 and 20 per cent concentration, the use
of 15 per cent volatile oil was considered optimum for checking the growth of
three used fungi. Reduced mycelial growth rate of different fungi by use of
volatile oil was probably attributed to the presence of HCN content in the volatile
oil. In conformation to these observations Lechtenberg and Nahrstedt (1999)
reported the discovery of structure of HCN-librating compounds in bitter
almonds by Robiquet and Boutron-Chalard in 1830 which possessed anti-
microbial activity. This compound was named as amygdalin as it was isolated
from Prunus amygdalus. According to Franks et al. (2005) diglucosidase
amygdalin was the first measure to be isolated as a natural product called as
cyanogenic glucosides found in many plant species, upon disruption of plant
tissue containing cyanogenic glucosides, these are hydrolysed by β-glucosidase
with concomitant release of glucose, an aldehyde or ketone and hydrocyanic acid
(HCN). Thus, the presence of HCN content in the apricot press cake volatile oil
57
might be attributed to the inhibition of mycelial growth in plant pathogenic fungi.
It was further revealed from the study (Table 4.10) that the one of volatile oil
exhibited significant inhibitory effect on the mycelial growth of different fungi.
Application of 10 per cent volatile oil brought about 100 per cent inhibition in
mycelial growth in Fusarium sp. followed by 83.5 per cent in Macrophomina sp.
and 98.06 per cent in Sclerotium sp. However, complete inhibition of mycelial
growth of the three plant pathogenic fungi was found when 15 per cent or more
concentration of volatile oil was used. According to Espinel-Ingroff et al. (2002)
and Dellavalle et al. (2011) the minimum fungicidal concentration (MFC) refers
to the lowest concentration that inhibits the fungal growth on the solid medium.
Thus, the use of 15 per cent volatile oil is considered to be the minimum
fungicidal concentration (MFC) of apricot volatile oil for all the three plant
pathogenic fungi. In conformation to these results Feminia et al. reported that
bitter apricot seed posses stronger and broader spectrum of anti-microbial activity
due to the presence of some metabolic toxins or broad spectrum anti-biotic
compounds. Thus, it can be concluded that 15 per cent concentration of apricot
kernel press cake volatile oil can significantly be used for inhibiting growth of
Fusarium, Sclerotium and Macrophomina sp.
Therefore, the anti-fungal property of volatile oil of apricot press cake
could be potential source of new and natural anti-fungal agent for treatment of
various skin diseases as well as control of plant pathogenic diseases.
CHAPTER–6
SUMMARY AND CONCLUSION
Studies on “Refinement of technology for extraction and utilization of
apricot kernel oil and press cake” were conducted in the Department of Food
Science and Technology, Dr. Y S Parmar University of Horticulture and Forestry,
Nauni, Solan (H.P.) during the years 2010-2013. Wild apricot stones left after
utilization of edible portion were procured in bulk from Karsog area in Mandi
district of Himachal Pradesh (1850 meter above mean sea level) and brought to
the Department of Food Science and Technology. The wild apricot stones before
or after pretreatments were decorticated using mechanical decorticator with
separating sieves (M/S Kisan Krishi Yantra Udyog Kanpur, India), specially
designed and modified for decortication of apricot stones. Mechanical separator
was developed by optimizing parameters like rolling surface of belt, soaking
pretreatments of apricot stones/kernels, speed of rolling belt, feeding conveyer
and forced air draft for separation of kernels and shells from the decorticated
stone mass. Steaming pre-treatments of apricot kernels with or without addition
of water was optimized for extraction of oil through Table oil expeller (M/S
Sardar Engineering Co, Kanpur, India). The press cake left after oil extraction
was utilized for extraction of volatile oil after pretreatment of press cake slurry.
The method for extraction of volatile oil from press cake was standardized using
Volatile oil distillation unit and Clevenger’s apparatus. The anti-microbial
properties of press cake based volatile oil were studied against Fusarium sp.,
Sclerotium sp. and Macrophomina sp. The results of these studies on various
aspects are summarized briefly as under:
1. Angle of static friction (θ) of soaked stones, kernels, shells and mixture of
shells as well as kernels on different rolling surfaces was more than the
un-soaked stone fractions. The highest angle of static friction was found
on rubber based rolling surface. Thus, the use of rubberized belt and
soaking of stones/kernels with an inclination angle of 22.5o was optimized
59
and adopted for use in development of mechanical separator for apricot
kernels.
2. Soaking of apricot stones/kernels affected the length, breadth, thickness,
geometric mean diameter and sphericty of stones and kernels. As the
moisture content of stones and kernels increased, the size parameters of
stones and kernels also increased. Size parameters of kernels such as
length (12.0 mm), breadth (9.0 mm), thickness (6.0 mm), geometric mean
diameter (8.6 mm) and sphericity (72.1 %) were increased to 12.6 mm,
9.4 mm, 7.0 mm, 9.4 mm and 74.6 per cent respectively, after soaking
treatments. Study of physical properties of apricot stones and kernels were
used in designing of equipments for kernel separation.
3. Soaking of stones/kernels before and after decortication improved the
efficiency of kernel separation in mechanical separator. Decortication of
pre-soaked apricot stones followed by further soaking of crushed stone
mass was found optimum for separation of apricot kernels with 4.60 kg of
kernels from 20 kg of crushed mass out of 5.85 kg of total kernel yield in
three passes. The kernel separation efficiency of Mechanical separator
was worked out to 78.6 per cent.
4. Steaming of apricot kernels with or without addition of water brought
about improvement in yield and quality of oil extracted through Table oil
expeller. Soaking of kernels by addition of 10 per cent water followed by
steaming (5 psi) for 15 min was considered optimum for achieving higher
yield (43.0 %) of expressed oil with minimum (2.5 %) amount of residual
oil in press cake.
5. Visual colour of extracted oil after different soaking and steaming
treatments remained deep yellow, thus indicating not any adverse change
in visual colour. However, according to Tintometer colour evaluation, the
yellow colour units in different oils exhibited a decline (6.4 in control to
5.2 in oil from moistened and steamed kernels). Apricot kernel oil
exhibited low acid value ranging from 2.27 to 2.77 mg KOH/g of oil.
Iodine value of extracted oil by using solvent extraction or Table oil
expeller with or without soaking and steaming treatments ranged between
60
100.2 to 100.6 g I2/100 g. Peroxide value ranged between 5.12 to 5.27
meq/kg was affected by the pretreatment of apricot kernels and method of
extraction. Steaming of kernels with or without soaking brought some
increase in peroxide value in the oil (5.24-5.27 meq/kg). Saponification
value of apricot oil extracted by using solvent extraction or Table oil
expeller with or without soaking and steaming treatments ranged between
189.7 to 191.7 mg KOH/g.
6. Oil extracted through soxtec oil extraction apparatus did not show the
presence of hydrocyanic acid (HCN) while press cake left after oil
extraction exhibited highest content (99.8 mg/100g) of HCN. Oil and
press cake obtained after steaming of kernels at 5 psi for 15 min did not
show any presence of HCN. However, oil extracted through Table oil
expeller after soaking of kernels without steaming showed the presence of
HCN.
7. The vitamin E content in oils ranged between 272-289 µg/g. Maximum
tocopherol content (289.0 µg/g) was found in oil obtained from expelling
of pre-soaked kernels in 10 per cent water. As expected, steaming of
kernels caused some change in vitamin E content of the extracted oil.
8. The soaking and steaming treatments of apricot kernels followed by oil
extraction through Table oil expeller did cause some change in the fatty
acid composition of extracted oil. Among the oil extracted through Table
oil expeller, the level of palmitic acid (7.82-7.84 % w/w), palmitoleic acid
(0.52-0.58 % w/w), stearic acid (0.97-1.03 % w/w) and oleic acid (63.13-
63.18 % w/w) was higher in oil extracted after soaking and steaming of
kernels.
9. Collection of 1 per cent distillate from 10 litres of diluted press cake
(1:10) obtained after maceration at 50 oC for 12 hours followed by
collection of 50 per cent distillate after re-distillation of distillate
containing 3 per cent each of CaO and FeSO4 was optimized for
extraction of volatile oil from the apricot press cake which contained
29.77 per cent benzaldehyde without HCN.
61
10. The volatile oil exhibited inhibitory properties against mycelial growth of
some plant pathogenic fungi viz. Fusarium sp., Sclerotium sp. and
Macrophomina sp. The antifungal property of volatile oil of apricot press
cake could be a potential source of new antifungal agent against plant
diseases. Thus, 15 per cent concentration of apricot press cake volatile oil
can significantly be used for inhibiting growth of Fusarium sp.,
Sclerotium sp. and Macrophomina sp.
CONCLUSION
It can thus, be concluded from the present investigations that mechanical
separator having rubberized belt placed at an inclination angle of 22.5o moving in
upward opposite direction can be used for separation of kernels from pre-soaked
wild apricot kernel mass with about 78.6 per cent separation efficiency with no
apprehension of presence of salt in the kernels. Further, overnight soaking of
apricot kernels in 10 per cent water followed by steaming (5 psi) for 15 min can
be used as a pretreatment for extraction of oil through Table oil expeller with
about 43 per cent oil yield with complete removal of HCN from the oil. The press
cake left after oil extraction can also be utilized for extraction of volatile oil with
29.8 per cent benzaldehyde for its use in various formulations viz. flavourant,
antifungal agent etc. The method consisting of maceration of press cake slurry
(1:10) at 50 oC for 12 hrs followed by distillation to collect 1 per cent distillate
and its maceration along with 3 per cent each of CaO and FeSO4 to obtain about
50 per cent of the distillate was optimum for hydro-distillation of volatile oil. The
anti-fungal property of volatile oil of apricot kernel press cake could be a
potential source of new natural anti-fungal agent against plant diseases caused by
Fusarium sp., Sclerotium sp. and Macrophomina sp.
Thus, use of mechanical separator for separation of apricot kernels,
soaking and steaming of apricot kernels for extraction of oil in Table oil expeller
to improve yield and quality of oil and extraction and utilization of volatile oil
from left over press cake can be adopted by the entrepreneurs on a cottage scale.
CHAPTER – 7
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Dr. Y.S. Parmar University of Horticulture and Forestry, Nauni, Solan (HP) Department of Food Science and Technology
Title of Thesis : Refinement of technology for extraction and
utilization of apricot kernel oil and press cake Name of student : Himanshu Sharma Admission number : H-2010-22-M Major advisor : Dr. P. C. Sharma Major Field : Food Technology Minor Field(s) : i) Food Sci. & Tech. (Group-I)
ii) Food Sci. & Tech. (Group-II) Degree Awarded : M.Sc. Food Technology Year of Award of Degree : 2013 No. of pages in Thesis : 68+ No. of words in Abstract : 465
ABSTRACT
Technology for mechanical separation of apricot kernels, improvement in oil extraction and utilization of volatile oil from press cake for control of plant pathogens was evaluated and refined. Out of different rolling surfaces, the use of 22.5o inclination angle on rubberized belt was found optimum for separation of kernels in mechanical separator. The size parameters of apricot kernels after soaking increased. Geometric dimensions such as length (12.0 mm), breadth (9.0 mm), thickness (6.0 mm), geometric mean diameter (8.6 mm) and sphericity (72.0 %) of apricot kernels was recorded to increase to 12.6 mm, 9.4 mm, 7.0 mm, 9.4 mm and 74.6 per cent respectively after soaking treatment. Besides, soaking of stones or decorticated stone mass brought about significant improvement in separation of kernels through mechanical separator with 78.6 per cent separation efficiency. Steaming of kernels at 5 psi for 15 min after addition of 10 % water brought about significant improvement in oil yield extracted through Table oil expeller. Further, the quality characteristics of oil from steamed kernels ranging between 2.27-2.77 mg KOH/g acid value; 100.21-100.63 g I2/100g iodine value; 5.12-5.27 meq/kg peroxide value and saponification value 189.67-191.73mg KOH/g oil, were found within the specification as laid under Food Safety and Standard Act for almond oil. Besides, steaming of kernels caused complete removal of residual HCN from extracted oil and left over press cake. The oil also contained 272.0-277.0 µg/g vitamin E, which is regarded as natural anti-oxidant and make the oil suitable for cosmetic and pharmaceutical purpose. The oil was found rich in unsaturated fatty acid containing oleic (61.93-64.16 % w/w) and linoleic (25.66-27.71 % w/w) as the major fatty acid, fractions with only 8.61 to 8.87 per cent saturated fatty acids. The press cake left after oil extraction was found suitable for the extraction of volatile oil for various purposes. For extraction of volatile oil, the method consisting of maceration of press cake in water (1:10) at 50 oC for 12 hrs followed by extraction of 1 % distillate and re-distillation of distillate in 3 % each of CaO and FeSO4 followed by collection of 50 % of volatile oil with 29.8 % benzaldehyde was optimized. The volatile oil possessed good anti-fungal properties against some plant pathogenic fungi like Fusarium sp, Sclerotium sp and Macrophomina sp. At 15 % volatile oil concentration, 100 % mycelial growth inhibition was recorded in all the three fungi. Therefore, anti-fungal property of volatile oil of apricot kernel press cake could be a potential source of new natural anti-fungal agent against plant diseases caused by Fusarium sp, Sclerotium sp and Macrophomina sp. Thus, complete technology for mechanical separation of kernels, steaming of kernels for oil extraction and hydro-distillation of volatile oil from press cake can be adopted at commercial scale for utilization of apricot stones by the entrepreneurs.
Signature of Major advisor Signature of student
Countersigned
\
Professor and Head Department of Food Science and Technology
Dr. Y. S. Parmar University of Horticulture and Forestry Nauni, Solan-173 230 (H.P.)
AP
PE
ND
IX-I
AN
OV
A fo
r ef
fect
of s
oaki
ng tr
eatm
ents
of d
ecor
ticate
d ap
ricot
sto
ne fr
actio
ns o
n th
e an
gle
of s
tatic
fric
tion
(θ)
of s
tone
s, k
erne
ls, s
hells
an
d m
ixtu
re o
f she
lls a
nd k
erne
ls o
n di
ffere
nt r
ollin
g su
rfac
es
Sou
rce
of
Var
iatio
n
De
gre
e of
F
reed
om
Mea
n su
m o
f squ
ares
Sto
nes/
Pits
K
erne
ls
She
lls
She
lls+
Ker
nels
Un-
soak
ed
Soa
ked
Mea
n
Un-
soak
ed
Soa
ked
Mea
n
Un-
soak
ed
Soa
ked
Mea
n
Un-
soak
ed
Soa
ked
Mea
n
Tre
atm
ent
3 15
1.15
14
1.15
14
5.83
17
1.25
16
4.55
16
7.41
14
5.83
15
5.83
15
0.42
16
1.15
17
2.50
166
.74
Err
or
16
0.53
0.
56
0.34
0.
38
0.64
0.
26
0.50
0.
25
0.26
0.
72
0.3
1 0.
23
Tot
al
19
- -
- -
- -
- -
- -
- -
AN
OV
A fo
r ef
fect
of s
oaki
ng tr
eatm
ents
on
the
moi
stur
e an
d size
par
amet
ers
of a
pric
ot s
tone
s an
d ke
rnel
s.
Sou
rce
of
Var
iatio
n
De
gre
e of
F
reed
om
Mea
n su
m o
f squ
ares
Moi
stur
e K
erne
l Le
ngt
h
Ker
nel
Bre
adth
K
erne
l T
hick
ness
G
eom
etric
me
an
diam
eter
of K
erne
l S
pher
icity
of
Ker
nel
Sto
ne
Ker
nel
Tre
atm
ent
3 15
6.14
6 72
1.24
6 0.
249
0.20
2 1.
078
0.58
2
0.00
1
Err
or
16
0.02
5 0.
220
0.00
2 0.
003
0.00
3 0.
004
0.00
1
Tot
al
19
- -
- -
- -
-
ii
AN
OV
A fo
r ef
fect
of s
oaki
ng tr
eatm
ents
on
the
effici
ency
of k
erne
l sep
arat
ion
in m
echa
nica
l sep
arat
or
Sou
rce
of
Var
iatio
n
De
gre
e of
Fre
edom
Mea
n su
m o
f squ
ares
Tim
e ta
ken
for
sepa
ratio
n Q
uant
ity o
f ker
nel s
epar
atio
n R
ate
of k
ern
el s
epar
atio
n %
sep
arat
ion
Tre
atm
ent
3 1,
576.
967
0.01
7 0.
155
928.
167
Err
or
16
0.81
9 0.
002
0.00
3 0.
019
Tot
al
19
- -
- -
AP
PE
ND
IX-I
I
AN
OV
A fo
r ef
fect
of s
oaki
ng, s
team
ing
and
oil e
xtrac
tion
met
hods
on
the
yiel
d an
d qu
ality
of a
pric
ot oil
and
pre
ss c
ake
Sou
rce
of V
aria
tion
D
egr
ee
of F
reed
om
Mea
n su
m o
f squ
ares
Oil
yiel
d
Pre
ss c
ake
yiel
d
Res
idua
l oil
in p
ress
cake
Moi
stur
e
Ker
nels
O
il
Tre
atm
ent
6 21
.714
21
.524
16
.714
49
.810
0.
986
Err
or
14
0.35
0 0.
576
0.18
7 0.
111
0.00
2
Tot
al
20
- -
- -
-
ii
i
AN
OV
A fo
r ef
fect
of s
oaki
ng, s
team
ing
and
oil e
xtrac
tion
met
hods
from
apr
icot
ker
nels
on
the
qual
ity ch
arac
teris
tics
of e
xtra
cted
oil.
Sou
rce
of
Var
iatio
n
De
gre
e of
Fre
edom
Mea
n su
m o
f squ
ares
Aci
d
valu
e
Iodi
ne
valu
e
Per
oxid
e
valu
e
Sap
onifi
catio
n va
lue
HC
N in
oil
HC
N in
pre
ss
cake
Toc
ophe
rol
cont
ent
Tre
atm
ent
6 0.
090
0.06
5 0.
008
1.94
9 74
9.91
0 3,
764.
906
16
3.52
4
Err
or
14
0.00
1 0.
003
0.00
2 0.
005
0.01
3 0.
009
0.85
7
Tot
al
20
- -
- -
- -
-
AN
OV
A fo
r ef
fect
of s
oaki
ng, s
team
ing
and
oil e
xtrac
tion
met
hods
from
apr
icot
ker
nels
on
the
Fat
ty a
cid c
ompo
sitio
n (%
w/w
) of
ex
trac
ted
oil
Sou
rce
of
Var
iatio
n
De
gre
e of
Fre
edom
Mea
n su
m o
f squ
ares
Pal
miti
c ac
id
Pal
mito
leic
aci
d S
tear
ic a
cid
O
leic
aci
d
Lino
leic
aci
d
Lino
leni
c ac
id
Tre
atm
ent
6 0.
022
0.02
1 0.
018
2.19
7 1.
859
0.10
4
Err
or
14
0.00
1 0.
003
0.00
2 0.
012
0.00
7 0.
003
Tot
al
20
- -
- -
- -
iv
AP
PE
ND
IX-I
II
AN
OV
A fo
r st
anda
rdiz
atio
n of
met
hod
for
extr
actio
n of
hyd
ro-d
istil
late
/vol
atile
oil
from
apr
icot
ker
nel p
ress
cak
e
Sou
rce
of
Var
iatio
n
De
gre
e of
F
reed
om
Mea
n su
m o
f squ
ares
B
enza
ldeh
yde
R
esid
ual H
CN
S
peci
fic g
ravi
ty o
f Vol
atile
oil
Tre
atm
ent
3 20
6.36
8 2,
332.
831
0.01
2 E
rror
8
0.03
2 0.
020
0.00
1 T
otal
11
-
- -
AN
OV
A fo
r ef
fect
of d
iffer
ent c
once
ntra
tions
(%
) of
apr
icot
pre
ss c
ake
vola
tile
oil o
n th
e m
ycel
ial g
rowth
rat
e of
som
e pl
ant p
atho
geni
c fu
ngi
Sou
rce
of V
aria
tion
D
egr
ee
of F
reed
om
Mea
n su
m o
f squ
ares
F
usa
riu
m s
p.
Scl
ero
tium
sp.
Mac
roph
omin
a sp
.
Tre
atm
ent
6 27
5.94
1 18
8.41
1 20
5.73
7 E
rror
14
0.
002
0.02
2 0.
005
Tot
al
20
- -
- A
NO
VA
for
inhi
bito
ry e
ffect
of a
pric
ot p
ress
cak
e vo
latil
e oi
l aga
inst
som
e pl
ant p
atho
geni
c fu
ngi
Sou
rce
of V
aria
tion
D
egr
ee
of F
reed
om
Mea
n su
m o
f squ
ares
M
GI a
t 5%
M
GI a
t 10
%
Tre
atm
ent
2 23
5.14
7 44
7.40
6 E
rror
6
0.00
1 0.
003
Tot
al
8 -
-
CURRICULUM VITAE
Name : Himanshu Sharma
Father’s Name : Sh. Ved Prakash
Date of Birth : 31st Dec, 1987
Sex : Male
Marital Status : Unmarried
Nationality : Indian
Educational Qualifications:
Certificate/ degree Class/ grade
Board/ University Year
10+2 First HP Board of School Education.
2006
B.Sc. (Horticulture) First Dr.Y.S.P. Univ. Of Horticulture & Forestry
Nauni- Solan
2010
Whether sponsored by some state/ : NA
Central Govt./Univ./SAARC
Scholarship/ Stipend/ Fellowship, any : University Stipend
other financial assistance received
during the study period
(Himanshu Sharma)