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STUDIES ON PRESERVATION AND PROCESSING OF CUSTARD APPLE (Annona squamosa L.) PULP

By

T. SRAVANTHI B.Sc (Food Science)

THESIS SUBMITTED TO ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY

IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DEGREE OF

MASTER OF FOOD SCIENCE TECHNOLOGY

INTERFACULTY PG PROGRAMME

POST GRADUATE AND RESEARCH CENTRE ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY

RAJENDRANAGAR, HYDERABAD – 500 030

MARCH, 2004

STUDIES ON THE PREPARATION OF SQUASH, NECTAR, RTS AND JUICE BLENDS FROM

WATERMELON FRUITS

By

FATHIMA FARHEEN B.Sc.

THESIS SUBMITTED TO ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY

IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DEGREE OF

MASTER OF FOOD SCIENCE AND TECHNOLOGY

INTERFACULTY PG PROGRAMME

POST GRADUATE AND RESEARCH CENTRE ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY

RAJENDRANAGAR, HYDERABAD – 500 030

APRIL, 2004

CERTIFICATE

I, T. SRAVANTHI has satisfactorily prosecuted the course of

research and that the thesis entitled “STUDIES ON PRESERVATION

AND PROCESSING OF CUSTARD APPLE (Annona squamosa L.)

PULP” submitted is the result of original research work and is of

sufficiently high standard to warrant its presentation to the examination.

I also certify that the thesis or part thereof has not been previously

submitted by her for a degree of any university.

Date : (Dr. Y. NARAYANA REDDY) Place : Hyderabad Major Advisor

CERTIFICATE This is to certify that the thesis entitled “STUDIES ON PRESERVATION AND PROCESSING OF CUSTARD APPLE (Annona squamosa L.) PULP” submitted in partial fulfillment of the requirements for the degree of MASTER OF FOOD SCIENCE AND TECHNOLOGY of the Acharya N.G. Ranga Agricultural University, Hyderabad, is a record of the bonafide research work carried out by T. SRAVANTHI under our guidance and supervision. The subject of the thesis has been approved by the student’s advisory committee. No part of the thesis has been submitted for any other degree or diploma. The published part has been fully acknowledged. All assistance and help received during the course of the investigation have been duly acknowledged by the author of the thesis.

(Dr. Y. NARAYANA REDDY) Chairman of the Advisory Committee

Thesis approved by the student advisory committee Chairman (Dr. Y. NARAYANA REDDY)

Professor and Univ. Head, Department of Horticulture, Rajendranagar, Hyderabad-30.

Member

(Dr. J. DILIP BABU) Senior Scientist, AICRP on PHT, Rajendranagar, Hyderabad-30.

Member

(Dr. R. SUBHASH REDDY) Associate Professor and Univ. Head Department of Agricultural Microbiology and Bioenergy, Rajendranagar, Hyderabad-30.

Member (Dr. S. SUMATHI) Associate Professor, Post Graduate Research Centre Rajendranagar, Hyderabad-30.

DECLARATION

I, T. SRAVANTHI hereby declare that the thesis entitled

“STUDIES ON PRESERVATION AND PROCESSING OF CUSTARD APPLE

(Annona squamosa L.) PULP” submitted to the ACHARYA N.G.

RANGA AGRICULTURAL UNIVERSITY for the degree of

MASTER OF FOOD SCIENCE AND TECHNOLOGY is the result

of original research work done by me. I also declare that any material

contained in the thesis has not been published earlier.

Date : (T. SRAVANTHI)

CONTENTS

Chapter

Title

Page No.

I INTRODUCTION

II REVIEW OF LITERATURE

III MATERIALS AND METHODS

IV RESULTS

V DISCUSSION

VI SUMMARY

LITERATURE CITED

APPENDICES

ABBREVATIONS

RTS - Ready to serve

TTS - Total soluble solids

SO2 - Sulphurdioxide

ppm - Parts per million

N - Normality

NaoH - Sodium hydroxide

HCl - Hydrochloric acid

TPC - Total plate count

ANOVA - Analysis of variance

F.P.O. Specifications

Squash Minimum % of TSS in final

product (w/w)

40

Nectar Minimum % of TSS in final

product (w/w)

15

RTS - Minimum % of TSS in final

product (w/w)

10

Permissible limits of preservatives

Squashes SO2 350 ppm

RTS SO2 100 ppm

Pulp SO2 1000 ppm

SCORE CARD Name of the evaluator: Date : Time : You are requested to evaluate the products prepared with water melon for the following sensory attributes as per the guidelines indicated below.

Attributes 1 2 3 4 5 6

Appearance

Color

Flavour

Taste

Overall acceptability

Comments / suggestions :

Signature of evaluator

Scores : Excellent : 5 Good : 4 Fair : 3 Poor : 2 Very poor : 1

S. No. List of tables Page No.

1. Physico-chemical characteristics of custard apple pulp and its products before storage

2. Organoleptic characteristics of custard apple products before storage

3. Microbiological characteristics of custard apple pulp and its products before storage

4. pH of processed custard apple products

5. Total soluble solids of custard apple products

6. Acidity of custard apple products

7. Ascorbic acid of custard apple products

8. Sulphur dioxide of custard apple products

9. Reducing sugars of custard apple products

10. Total sugars of custard apple products

11. Appearance of custard apple products

12. Colour of custard apple products

13. Flavour of custard apple products

14. Taste of custard apple products

15. Overall acceptability of custard apple products

16. Total plate count of custard apple products

17. Yeast and mould count of custard apple products

S. No. List of plates Page No.

1. Products prepared from stored custard apple

pulp

2. Squash, nectar and RTS

3. Toffee

4. Products from stored custard apple pulp

5. Custard apple products after four months

storage

S. No. List of Figures Page No.

1. pH of stored custard apple products

2. Total soluble solids of stored custard apple

products

3. Acidity of stored custard apple products

4. Ascorbic acid of stored custard apple products

5. Sulphurdioxide of stored custard apple

products

6. Reducing sugars of stored custard apple

products

7. Total sugars of stored custard apple products

Acknowledgements It is due to the blessings of Shirdi Sai that I have been able to complete my studies successfully hitherto and present this piece of work for which I am eternally debated. Accompliments of this thesis is the result of benevolence of His divine grace. I am pleased to place my profound etiquette and indebtedness to my major guide Dr. Y. Narayana Reddy for suggesting the research work, for the unstincted attention, arduous and meticulous guidance given through out my research investigation despite of his hectic academic schedule. I extol the genuine cooperation and inspiration given to me right from the initiation of work to ship shaping of the manuscript. It was indeed a real privilege for me to work under his unending inspiration and undomitable spirit. I fervently and modestly thank Dr. J. Dilip Babu, member of my advisory committee for his guidance and help provided during my investigation. Ineffable is my gratitude and sincere thanks to Dr. Subhash Reddy, member of the advisory committee for his support during my research work. I humbly offer my sincere thanks to Dr. Sumathi, member of the advisory committee for her guidance and encouragement offered during my course work. I owe my flow of thanks to Dr. Deva muni Reddy and Naram Naidu for their guidance offered during my course work. I owe an encompassing debt to my most beloved parents Ram Reddy and Roja and my grand mother Kousalya who taught me the concept of life. They have constantly inspired, educated, guided and molded into the present situation and whose encouragement brings out my best in each one of my endeavors. There is no match to the affection and co-operation given to me by my brothers Sravan, Rahul, Rajeev and cousin Deepthi. It is with love, I wish to place or record the unbounded affection, cheerful encouragement and co-operation extended to me by my beloved husband Kodanda Rama Reddy during my research work. I accolade my highest respects to my beloved in-laws for their affection and blessings, which helped me to move successfully.

Diction is not enough to express my deep sense of gratitude and affection for my ever loving friends Krishnalatha, Himabindu, Srividya and Sunanda who had always showed me their everlasting affection, co-operation and lovely company. The fond memories of the time spent with them are going to be cherished forever by me. It is time to surface out my affection and genuflect love to my colleagues Vijayabhanu, Ramesh, Radha, Yellamanda, Farheen, Ramana, Sudheer, Soujanya, Vinoothna and Smitha. Who made my college life a memorable one. A special word of thanks to all my juniors for their alacrity and support. Lastly I wish to extend my thanks to one and all who contributed even in a small way in the completion of my research work Date:

T.Sravanthi

Name of the Author : T. SRAVANTHI

Title of the Thesis : “STUDIES ON PRESERVATION AND

PROCESSING OF CUSTARD APPLE (Annona squamosa L.) PULP”

Degree to which it is submitted

: MASTER OF FOOD SCIENCE AND TECHNOLOGY

Faculty : Inter faculty P.G. Programme

Department : Post graduate and research center

Major Advisor : DR. Y. NARAYANA REDDY

University : Acharya N.G. Ranga Agricultural University, Rajendranagar, Hyderabad-30.

Year of submission : 2004

ABSTRACT

Custard apple is one of the important fruit crops of Andhra Pradesh, which ripen within four days after harvest. Considering the fast increasing area under custard apple cultivation, methods of its preservation and processing technology needs to be developed to regulate the prices of produce during glut period.

Pulp was extracted from custard apples and stored for a period of

six months by addition of 1500 ppm of potassium metabisulphite. After six months, various products like squash, nectar, ready-to-serve beverage (RTS) and toffee were prepared.

The products were stored at room temperature and cold storage

for a period of four months to study the stability and consumer acceptability of the products. The products were analysed every month for physico-chemical and organoleptic qualities. The microbiological safety of these products was also evaluated.

The pH, acidity, ascorbic acid and sulphurdioxide were lower in

all the products compared to the stored pulp whereas, TSS, reducing and total sugars were high. Microbial count was negligible and E. coli were completely absent on all the products. The products ranked excellent in all organoleptic qualities.

All the products stored at cold storage were good physico-

chemically, microbiologically and organoleptically when compared to the products stored at room temperature.

pH and TSS were found to be more in products stored at cold

storage compared to room temperature. Acidity of squash and nectar stored at cold storage was more than that at room temperature. Ascorbic acid retention was more in squash and nectar stored at cold storage but a decrease was observed in RTS and toffee. SO2 was more in all the products stored at cold storage. Squash and nectar stored at cold storage were found to have more reducing and total sugars than that stored at room temperature. There was a decrease in reducing and total sugars in RTS and toffee stored at cold storage. The products stored at room temperature were accepted till third month of storage whereas, the products stored at cold storage showed an over all acceptability upto four months of storage. Increase in microbial growth with storage period was observed in all the products but the increase was more in the products stored at room temperature to that at cold storage.

The acceptability of the products decreased gradually with

increase in storage time. The pH and TSS of all the products decreased upon storage. Acidity of all the products increased with increase in storage period. In squash, nectar and toffee ascorbic acid content increased with the storage period. SO2 and reducing sugars of all the products decreased with the storage period. There was an increase in total sugars in squash and toffee with increase in storage period but total sugars reduced in RTS and nectar upon storage. The results showed that the products can well be stored for at least four months without deterioration preferably at cold storage.

CHAPTER – I

INTRODUCTION

Custard apple, (Annona squamosa L.) is one of the important fruit

crops of Andhra pradesh. Nearly, 75,000 tonnes of this fruit is available

from the state. Custard apple is a hardy crop, which can be grown on

marginal lands with minimum inputs. Custard apple, popularly known as

sharifa or sitaphal is grown in about 40,000 ha in India mainly in the states

of Andhra pradesh, Assam, Tamil nadu and grows wild in Deccan plateau

and some parts of central India.

Custard apple is considered as one of the delicious and nutritionally

valuable fruit meant for table pupose. Fruits have an edible, soft, granular,

juicy and sugary pulp with mild flavour and with slight acidity. Fruits are

considered for their medicinal value besides their general use in ice cream,

confectionery and certain milk products.

Custard apple ripen within four days after harvest. Fruits can safely

be ripened in straw and fruit leaves and stored at room temperature with a

shelf life of four days. The ripe fruits being soft require careful handling in

marketing. Like many other tropical fruits, the mature custard apple fruits

get chilling injury if stored below 15C, while ripe fruits can be stored at

5C, for six weeks (Jagdish prasad et.al.1995). Considering the fast

increasing area under custard apple cultivation, methods of its preservation

and processing technology needs to be developed to regulate the prices of

produce during glut period.

Custard apple contains about 28-55 % of edible portion consisting of

73.30 % of moisture, 1.60% protein, 0.30% fat, 0.70% mineral matter,

23.90% carbohydrates, 0.20% calcium, 0.04% phosphorous, 1.0% iron,

12.4 to 18.15% sugar, 0.26 to 0.65% acidity with a total calorific value of

105 calories /100 g.

The present study is conducted with the following objectives:

1. Storage of the custard apple pulp and assessment of the quality of stored

pulp.

2. Preparation of value added products like squash, nectar, ready-to-serve

(RTS) beverage and toffee from custard apple pulp.

3. To study the shelf life of products prepared, at room temperature and

cold storage for a period of 4 months.

4. To evaluate the quality of the products at regular intervals.

CHAPTER – II

REVIEW OF LITERATURE

Review of literature pertaining to the present study is presented

under the following sections.

1. Physico-morphological characters and chemical composition of

custard apple.

2. Extraction of pulp.

3. Storage of pulp.

4. Preparation of products.

5. Shelf life of the products.

Physico-morphological characters and chemical composition of

custard apple:

The general composition, adaptability, ripening, storage and

marketing of custard apple were studied. Custard apple is considered

as one of the delicious and nutritionally valuable fruit. Custard apple

contains about 28-55% of edible portion consisting of 73.30%

moisture, 1.60% protein, 0.30% fat, 0.70% mineral matter, 23.90%

carbohydrates, 0.20% calcium, 0.40% phosphorous, 1.0% iron, 12.4-

18.15% sugar, 0.26-0.65% acidity and with a calorific

value of 105 calories / 100 g. Custard apple is generally

classified as semi wild fruit by virtue of its spontaneous spread in

forests, wastelands and other uncultivated places. Custard apple

ripen within four days after harvest. Fruits can safely stored at

room temperature with a shelf life of four days when treated with

calcium carbide and further ripened in straw and fruit leaves

(Jagdish prasad et.al., 1995).

Physico-morphological characters and chemical

composition of custard apple fruits of 7 varieties viz.,

Washington PI-107005, Balanagar, Red sitaphal, Washington PI-

98797, Mammoth, Local sitaphal, British Guinea were studied.

The total soluble solids varied from 20.60-280 brix, total sugars

from 14.9-21.6 percent. Custard apple fruits of all varieties were

poor source of vitamin C, pectin and protein (Beerh et.al., 1983).

Extraction of pulp:

The extraction of pulp from ripe bael fruit by addition of

water equal to pulp (with seeds and fibre), adjusting the pH to 4.3

with citric acid and heating at 80C for 1 minute was described.

The application of heat not only inactivated the enzymes but also

helped in dissolving the mucilage uniformly to provide a

homogenous pulp (Roy et al., 1979).

Kotecha et.al., (1995) and Dhumal et.al., (1996) described

the extraction of pulp from ripened custard apple fruits. The

ripened fruits were washed and cleaned thoroughly and the pulp

was extracted manually by cold hand press extraction method

and was homogenized in an automatic mixer.

Storage of pulp:

Preparation and storage of pulp, squash, nectar and ready-

to-serve beverages from two varieties of apricots grown in

Kumaon region of Uttar pradesh was studied. Storage studies on

apricot pulp have shown that the pulp quality was satisfactory

upto 9 months of storage at room temperature (13 –43 C).

Nectars and squashes were also prepared and adjudged

satisfactory upto 6 months storage (Manan et.al., 1992).

The shelf life of guava pulp stored at 5 C by addition of

potassium metabisulphite, ascorbic acid either alone or

combination with heating at 85 C was studied. After 3 months,

the unspoiled pulp was utilized for the preparation of ready-to-

serve beverage (Rouhangiz Hayati et.al., 1992).

Litchi pulp was preserved and used for squash making. At

low temperature pulp stays fresh for more than a year by addition

of 1g/l of potassium metabisulphite (Vijay sethi et.al., 1983).

Preparation of products:

For the extraction of juice from custard apple pulp 0.2%

pectinase and 4 hrs incubation period were found to be optimum.

The organoleptic evaluation of RTS showed that the beverage

prepared by using 20% juice was most acceptable (Kotecha et.al.,

1995).

Chauhan et.al., (1993) prepared highly acceptable juice

beverages from apricot, peach and plum by blending 20% pulp,

7% sugar, 0.1% salt and 0.1% citric acid.

Guava pulp treated with 0.1% potassium metabisulphite

packed in glass containers or poly vinyl chloride and stored at 5

C for 3 months can be utilized for beverage production which is

comparable with RTS prepared from fresh pulp due to its better

colour, taste and flavour (Rouhangiz Hayati et.al., 1992).

Different products like jam, chutney, squash, drink, toffee

and powder can be prepared from wild apricot for its profitable

utilization (Sharma et.al., 1993).

The process of preparation of bael fruit nectar with 35%

pulp, 25 brix and 0.3% acidity was described. Similarly, 50%

pulp, 50 brix and 1.0% acidity was found suitable for squash. A

good quality toffee was prepared by mixing bael fruit pulp (100

parts), sugar (40 parts), glucose (4.5 parts), skim milk powder

(10 parts) and hydrogenated fat (6parts). Sulphur dioxide (1500

ppm) was added before rolling into sheets (Roy et.al., 1979).

Papaya fruit based toffee can be prepared with added

bengal gram flour along with sugar, vanaspathi, glucose and

orange peel oil (Shastri et.al., 1979).

Custard apple toffees were prepared by using different

levels of sugar and skim milk powder. Good quality custard

apple toffees can be prepared by using 750g sugar, 20g skim

milk powder, 120g vanaspati, 2g citric acid and 5g salt per

kilogram of custard apple pulp (Dhumal et.al., 1996).

Shelf life of the products:

Except for slight reduction in reducing sugars content,

there was no marked changes in the chemical parameters of the

RTS beverages prepared from watermelon juice during 4 months

of storage (Chakraborthy et.al., 1993).

The chemical analysis of the products prepared from

stored guava pulp showed that the total acidity was almost same

as in fresh fruit and the stored pulp. The ascorbic acid of fruit

was lower than extracted pulp due to oxidation of ascorbic acid.

Reducing and total sugars were also higher in fresh fruit than in

the pulp. The pH of fruit was slightly higher than pulp

(Rouhangiz Hayati et.al., 1992).

Reduction in non-reducing sugars and increase in reducing

and total sugars was observed in bael fruit products after 6

months storage. There was practically no change in organoleptic

quality in frozen pulp after 6 months (Roy et.al., 1979).

Jamun juice and nectar could be successfully stored for

one year in cool chamber with a temperature ranging from 9.3-

26.5 C (Khurdiya et.al., 1985).

Ready-to-serve beverage prepared from two varieties of

jack fruits and stored at room temperature to study the storage

stability showed that there was an increasing trend in the acidity

and reducing sugars and decreasing trend in pH, total sugars,

ascorbic acid but, total soluble solids did not change during

storage. Sensory quality attributes were found to be increasingly

acceptable even after storing for 6 months at room temperature

(Krishnaveni et.al., 2001).

Aruna et.al., (1997) studied storage quality of papaya

nectar. The study revealed good keeping quality upto 6 months

and after that deterioration in physico-chemical, sensory and

microbiological qualities was observed.

CHAPTER-III

MATERIALS AND METHODS

The methodology of the study is presented in the

following sections

3.1 Location of the experiment

3.2 Experimental details

3.3 Preparation of the products

3.4 Shelf life study of the products

3.5 Data presentation

3.6 Statistical analysis

The details of the materials used and the methods adopted

during the course of present investigation entitled “studies on

preservation and processing of custard apple pulp” are elucidated

in this chapter.

LOCATION OF THE EXPERIMENT:

The experiment was carried out at Post Harvest

Technology, Department of Horticulture; Post graduate Research

Centre and Department of Agricultural Microbiology and

Bioenergy, college of Agriculture, Rajendranagar, Hyderabad.

Procurement of fruits:

Custard apples (Annona squamosa L.) were used for this

experiment. The fruits were procured in bulk from the local

market.

Chemicals:

Chemicals used in experimentation and analysis were of

analytical grade, purchased from standard Indian companies.

Media and chemicals used for microbial analysis were also from

standard companies.

EXPERIMENTAL DETAILS:

Extraction of pulp:

Fully ripened fruits were selected and the pulp was

extracted manually under hygienic conditions. The seeds and

pulp were separated from each other by rubbing the mixture on a

30-mesh sieve leaving the seeds and the covering sheath of the

carpellary pulp.

Storage of the pulp:

The extracted pulp was added with 1500 ppm of

potassium metabisulphite, packed in individual packs of 1kg and

½kg in polyethylene bags of 150 guage and stored at 5 C for a

period of 6 months from November 2002 to April 2003 till the

pulp is used for preparation of various products.

PREPARATION OF THE PRODUCTS:

After 6 months of storage, the stored pulp was analyzed

both chemically and microbiologically before preparing the

products and utilized for various products preparation.

The various products prepared from custard apple pulp

are:

1. Squash

2. Nectar

3. Ready-to-serve beverage

4. Toffee

Method of preparation:

Squash

Ingredients used

Pulp: 1 Kg

Sugar: 1.8 Kg

Water: 1 l.

Potassium metabisulphite: 0.6 g/l. squash

Citric acid: 5 g

Sugar syrup was prepared to which citric acid was added.

The syrup was cooled and homogenized pulp was added and

mixed thoroughly. Potassium metabisulphite was added as

preservative, filled in bottles and capped. Squash needs to be

diluted before serving.

Flow chart for preparation of squash

Preparation of syrup

(Sugar + water +citric acid, heating just to dissolve)

Straining

Mixing with homogenized pulp

Addition of preservative

Bottling

Capping

Storage

Ready-to-serve beverage

Ingredients used

Pulp: 1 Kg

Sugar: 1.2 Kg

Citric acid: 28g

Water: 7.7 l.

Homogenized pulp was mixed with sugar solution of 13

brix to which citric acid was added and filled in sterilized bottles.

The bottles were filled till it overflows to remove air and foam,

crown corked and pasteurized at 90C for 25 minutes, cooled and

stored. Ready-to-serve beverage should not be diluted before

serving.

Flow chart for preparation of RTS beverage

Fruit pulp

Mixing with strained syrup solution

(Sugar + water + acid, heated just to

dissolve)

Bottling

Crown Corking

Pasteurization at 90 C/25 minutes

Cooling

Storage

Nectar

Ingredients used

Pulp: 1 Kg

Sugar: 0.6 Kg

Citric acid: 13g

Water: 3.3l.

Homogenized pulp was mixed with sugar solution of 15

brix to which citric acid was added .The solution was filled in

sterilized bottles till it overflows to remove air and foam. They

are then crown corked and pasteurized at 90C for 25 minutes,

cooled and stored.

Flow chart for preparation of nectar

Fruit pulp

Mixing with strained syrup solution

(Sugar + water + acid, heated just to dissolve)

Bottling

Crown corking

Pasteurization at 90 C/25 minutes

Cooling

Storage

Toffee

Ingredients used

Fruit pulp: 5.3 Kg.

Sugar: 3 Kg.

Glucose: 0.5 Kg.

Skim milk powder: 0.5 Kg.

Vanaspathi fat: 0.5 Kg.

Pulp was concentrated to 1/3 its original weight by

stirring. Ingredients like sugar, vanaspathi, and glucose were

added and cooked till a drop of the product put in water forms a

compact mass. Skim milk powder dissolved in small amount of

water was then added to the mixture and continued cooking till

the mass leaves the sides of vessel. The final product was

transferred into greased plates and allowed to set. It was then cut

into small pieces, wrapped in butter paper and stored.

Flow chart for preparation of toffee

Homogenized pulp

Concentrating the pulp to 1/3rd its volume by

stirring

Addition of sugar, glucose

Putting fat/ghee in pan

Transfer pulp to pan

Cooking till sufficiently solid

Addition of skim milk powder dissolved in water

Spreading on greased plate

Cooling and cutting into pieces

Wrapping in butter paper

Storage in air tight containers

SHELF LIFE STUDY OF THE PRODUCTS:

The prepared products were stored both at room

temperature and cold storage (5-10C) to study the shelf life of

the products. The products are initially analyzed chemically,

microbiologically and organoleptically before storage.

Observations recorded:

Custard apple attains a bitter taste upon exposure to heat,

but it is interesting to note that there was no such bitterness

observed in any of the products prepared even though all the

products prepared involved heat processing. The products were

analyzed at an interval of every 30 days for the following

parameters and recorded.

Physico-chemical analysis of the products:

pH:

The pH of the products was determined by using a pH

meter.

Total soluble solids ( 0 brix ):

The percentage of total soluble solids were determined by

using “Erma” hand refractometer and expressed as percent total

soluble solids ( 0 brix ) (Ranganna, 1986).

Acidity:

The acidity of the samples was determined by diluting an

aliquot of the sample with distilled water and titrating with 0.1N

NaoH using phenolpthalein as indicator. The calculated acidity

was expressed as percent anhydrous citric acid.

Sugars (%):

Reducing sugars and total sugars were determined by the

method of “Lane and Eynon” (1923).

Reducing sugars:

To 25g of the sample in a volumetric flask 100ml of water

was added and neutralized with 1N NaoH. 2ml of 66% lead

acetate solution was added and kept for 10 minutes. Excess lead

acetate was precipitated by necessary amount of 20% potassium

oxalate, made upto the volume with water, filtered and taken in

burette.

10ml of mixed Fehling’s solution was taken in 250ml

conical flask. Little quantity of the sample was run into flask and

heated to boil moderately for 2 minutes. 3 drops of methylene

blue solution was added and completed the titration until the

indicator was completely decolourized. Brick red colour of the

solution indicates the end point.

Total sugars:

For total sugars 50ml of filtered sample was taken in a

250ml conical flask to which 50ml water and 5g of citric acid

was added, boiled gently for 10 minutes to complete the

inversion of sucrose, transfered to 250ml volumetric flask and

neutralized with 1N NaoH. The volume was made upto the mark

and determined the total sugars as invert sugars.

Ascorbic acid (mg/100ml or 100g sample):

Ascorbic acid was estimated by visual titration method

(Ranganna, 1986).

10ml of the sample was made upto 100ml with 3%

metaphosphoric acid and filtered. To estimate the interference of

sulphur dioxide in the sample, 10ml of the filtrate was taken and

added with 1ml of 40% formaldehyde and 0.1ml 0f Hcl and kept

for 10 minutes. The sample was titrated with the standard 2,6-

dichlorophenol-indophenol dye to a pink end-point that should

persist for atleast 15 seconds.

Sulphur dioxide:

Sulphur dioxide in the sample was calculated by modified

“Ripper titration” method (Ranganna, 1986).

To two similar aliquots of the sample 5ml of 5N NaoH

was added and allowed to stand for 20 minutes. To one of the

samples 7ml of 5N HCl was added and titrated immediately with

0.02N iodine to a definite dark blue colour with 1% starch

solution as indicator (a).

To determine the reducing substances other than sulphite,

the second sample was also acidified with 7ml of 5N Hcl and

10ml of 36-40% formaldehyde was added and kept for 10

minutes. The sample was titrated until a dark blue colour persists

for atleast 15 seconds (b). Volume of iodine used by the total

sulphur dioxide present in the sample is equal to (a-b) ml.

Organoleptic evaluation of the products:

The products developed from custard apple were assessed

every month by a panel of 10 judges. The qualities considered

during the study were appearance, colour, flavour, taste and

overall acceptability.

Selection of panel members:

Panel members were selected from students of food

science and technology, Acharya N.G. Ranga Agricultural

university, Rajendranagar, Hyderabad.

Development of score card:

In order to evaluate the sensory qualities of developed

products, descriptive test, which analytically describes the

sensory qualities of a product, was used. In order to rank the

sensory qualities, ordinal scoring method (ranking) was used

(Peryam and Pilgrim, 1957). Five-point scale was used for

ranking i.e., from 1 to 5 and details of ranks/scores are as

follows.

5 – Excellent

4 – Good

3 – Fair

2 – Poor

1 – Very poor

A score card was developed to evaluate the acceptability

of the products. The analysis was carried out in a room, which

was free from all disturbances in mid afternoon (3pm).

Microbiological evaluation of the products:

Microbiological studies were conducted at 1st and 3rd

month of storage. Total plate count (TPC), yeast and mould

count, coliform and E.coli were undertaken.

The procedure of Cruick Shank et.al, (1975) was used for

total plate count and yeast and mould count. The microbiological

study was carried out at Agricultural Microbiology and

Bioenergy Department, College of Agriculture, Rajendranagar,

Hyderabad.

Total plate count and yeast and mould count by pour-plate

method

Reagents used

Normal saline: 0.8%

Standard plate count agar

Potato dextrose agar

Equipment and Materials used

Petriplates

Test tubes

Pipettes

Spatula

Incubation chamber

Microscope

Procedure

Ten-fold serial dilution of the bacterial suspension was

prepared. Normal saline was used as a diluent for the organism.

9ml of the diluent was pipetted into several sterile test tubes. The

bacterial suspensions were uniformly mixed. Using a sterile 1ml

pipette, 1ml of the suspension was transferred into the first tube

of diluent and mixed thoroughly. From this mixed dilution, 1ml

was transferred to the next diluent. Similar dilutions were made

in the same way using fresh pipettes.

1ml of each dilution (from the greatest dilution) was

pipetted into sterile petri plates and 15ml of molten agar medium

which was cooled around 45 C was poured into plates

containing diluted samples. The agar medium was immediately

distributed by gently mixing the petridish in circular movements

both clock wise and anti clock wise on a flat bench and then

allowed to set evenly and the inverted plates were incubated for

1-2 days and 3-5 days at 37 C for bacterial and yeast and

moulds respectively.

For total plate count, total plate count agar and potato

dextrose agar for yeast and mould count was used.

Coliform and E.coli count:

Media used

Lactose broth

Eiosine- methylene blue (EMB) agar

Equipment and Materials used

Test tubes

Durham’s tubes

Agar medium plates/ Petri plates

Pipettes (10, 1 ml).

Procedure

10ml of the sample was inoculated in double strength

lactose broth in 5 test tubes, 1ml in 5 test tubes single strength

lactose broth and 0.1ml in other set of lactose broth test tubes and

incubated at 35C for 24+/- 2hrs. After incubation they were

observed for gas production. Gas production in Durham’s tubes

indicates positive test. Positive test tubes were separated and

inoculated in Brilliant green lactose bile broth and incubated for

24-48hrs. Presence of gas production indicates positive test.

From the positive tubes, inoculated in EMB agar and streaking

was done. The plates were incubated for 24-48hrs. After the

development of colonies, they were differentiated by observing

colony morphology and Gram’s staining.

DATA PRESENTATION:

All the details pertaining to physico-chemical changes in

the processed products like acidity, reducing and total sugars

were presented per 100g of the product. Thus all the values were

represented as percentage. Sulphur dioxide was represented as

ppm and ascorbic acid as mg/100g of the sample. The sensory

qualities of each parameter were expressed for 5 points since the

highest rank was 5. Microbiological qualities in the products

were presented for 1ml.

STATISTICAL ANALYSIS

In order to understand the significant changes on storage,

analysis of variance (ANOVA) and CRD test was carried out for

sensory parameters like colour, appearance, flavour, taste and

overall acceptability for each product (Panse and Sukhatne,

1985). Similar analysis was done to understand the significant

changes in the physico-chemical characteristics such as pH, total

soluble solids, acidity, ascorbic acid, sulphur dioxide, reducing

and total sugars.

CHAPTER - IV

RESULTS

Various custard apple products were developed at laboratory

level and stability of these products at two different storage conditions

were evaluated. The results were subjected to appropriate statistical

analyses and presented in this chapter.

1. Laboratory studies

1.1 Development of processed custard apple products

Four products were developed with custard apple pulp stored for

6 months at 5C. They include squash, nectar, ready-to-serve beverage

(RTS) and toffee. Physico-chemical characteristics, organoleptic

qualities and microbial safety of processed custard apple products, were

studied.

Procedure for preparation of the products

Squash

Sugar syrup was prepared with 1.8 kg sugar in 1 l of water to

which citric acid was added. The syrup was cooled and 1 kg of

homogenized pulp was added and mixed thoroughly. 0.6 g / l potassium

metabisulphite was added as preservative, filled in bottles and capped.

RTS

1 kg of homogenized pulp was mixed with sugar solution of 13

brix to which 28 g of citric acid was added; filled in sterilized bottles.

The bottles were filled till it overflows to remove air and foam, crown

corked and pasteurized at 90C for 25 minutes, cooled and stored.

Nectar

1 kg of homogenized pulp was mixed with sugar solution of 15

brix to which 13 g of citric acid was added. The solution was filled in

sterilized bottles till it overflows to remove air and foam, crown corked

and pasteurized at 90C for 25 minutes cooled and stored.

Toffee

5.3 kg of custard apple pulp was concentrated to 1/3 its original

weight and ingredients like 3 kg sugar, 0.5 kg vanaspathi, and 0.5 kg

glucose were added and cooked till a drop of product put in water forms

a compact mass. O.5 kg skim milk powder dissolved in small amount of

water was added to the mixture and continued cooking till the mass

leaves the sides of vessel, poured in to greased plates and allowed to set.

It was then cut into small pieces and wrapped in butter paper.

1.2 Physico – chemical characteristics of processed custard apple

products

Initially for all the processed products of custard apple, analysis

was carried out to determine the values for different parameters. The

initial values of the products before storage are presented in the table 1.

The pH was higher for squash (4.26) followed by nectar (3.74)

and RTS (3.34). The total soluble solids were higher in squash (510B).

Acidity was higher for nectar (0.44%) followed by toffee (0.39%).

Ascorbic acid was found to be higher in toffee (9.15 mg /100g) followed

by squash (6.96 mg/100ml). Sulphur dioxide was higher in squash (376

ppm). Reducing sugars and total sugars were higher in toffee [15.16 %

and 68.25%].

Effect of processing on physico – chemical characteristics of custard

apple products.

The pH was found to be lower in all the products when compared

to the stored pulp (5.62) from which the products were prepared. The

total soluble solids (TSS) were higher in squash compared to pulp. The

total acids were lower in all the products than the fruit pulp from which

the products were developed. Ascorbic acid loss was enormous in case

of all the products, except for a slight decrease in toffee. SO2 also

decreased enormously in all the products compared to the stored pulp on

processing. Reducing and total sugars were found to be higher in squash

and toffee compared to pulp on processing.

Organoleptic evaluation of processed custard apple products

A panel of 10 judges assessed the products developed from

custard apple initially. The qualities considered during the study were

appearance, colour, flavour, taste and overall acceptability. A maximum

score of 5 was taken as standard for considering the quality of the

product. All the processed products ranked excellent in all the qualities.

Data pertaining to the initial organoleptic evaluation of the custard apple

products are presented in table 2.

Microbial evaluation of processed custard apple products

The products developed were analyzed initially for microbial

quality. Microbial studies like total plate count (TPC), yeast and mould

count, coliform and E. coli count were carried out to evaluate the safety

and keeping quality of the products. Data pertaining to microbial

evaluation of processed custard apple products before storage are

presented in table 3. Squash contained higher number of TPC [90

CFU/ml] followed by toffee [70 CFU/g]. TPC were absent in nectar and

RTS initially before storage. Yeast and mould count were negligible in

all the products initially. Analysis of the products for coliform count

revealed their presence in pulp and nectar. E.coli were absent in all the

products.

1.3 Storage studies on processed custard apple products

The products developed, were stored at two different storage

conditions (i.e.) at room temperature and cold storage for a period of 4

months and their physico-chemical characteristics were evaluated every

month for different parameters.

pH

Data pertaining to pH are presented in table 4. There were

significant differences in pH among the products and storage periods at

different storage conditions. Squash contained significantly higher pH

(4.01) followed by nectar (3.54) and RTS (3.15). The pH was found to

be higher in products kept at cold storage compared to that at room

temperature. There was significant difference in pH of products among

the storage periods. The pH was least after 4 months of storage. It was

significantly lower than the 1st month of storage. pH during 3rd and 4th

month of storage were on par.

The interaction effects of products and storage conditions,

products and storage periods and storage periods and storage conditions

did not show any significant difference.

Total soluble solids (TSS)

Data pertaining to the total soluble solids are presented in table 5.

There were significant differences in total soluble solids among the

products during different storage periods and different storage

conditions. TSS was found to be significantly higher in squash. Nectar

and RTS contained lower amount. The TSS of nectar and RTS were

almost equal (13.37 and 13.00). The TSS was significantly higher in

products stored at cold storage (26.36) compared to that stored at room

temperature (25.90). There were significant differences in TSS of

products among different storage periods, but the difference was

gradual. There was significant decrease in TSS after 4 months of storage

compared to 1st and 2nd month of storage. There was a slight increase in

TSS during 2nd month of storage, which decreased significantly during

storage. It was on par with 1st month of storage. 3rd and 4th month of

storage period were at par.

The interaction effects of products and storage conditions were

significant. There was increase in TSS in squash but not in nectar or

RTS stored at cold storage. TSS of RTS was found to be same both at

cold storage and room temperature (13.00).

There were significant differences for the interaction effects

between products and storage periods. Squash contained higher TSS

followed by nectar. Second month of storage showed higher TSS, which

was on par with 1st month of storage, which in turn was on par with 3rd

and 4th month of storage.

The interaction effects were not significant between storage

period and storage conditions. Similar pattern was also observed

between products, periods and storage conditions.

Acidity

Data pertaining to acidity are presented in table 6. There were

significant differences in acidity among the products and the products

differed distinctly with each other. Nectar contained higher % of acidity

followed by toffee. Squash contained lower %. Acidity was significantly

higher in products stored at cold storage compared to that at room

temperature. There were significant differences in acidity of the

products at different storage periods. Acidity was least after 4 months of

storage. It was on par with 3 months storage and significantly lower than

1st, 2nd and 3rd months of storage.

The interaction effects of products and conditions were

significant. At room temperature acidity was more in toffee (0.41%)

followed by nectar (0.36%) and RTS (0.34%), which were at par. In

cold storage higher acidity was observed in nectar (0.49%) followed by

toffee (0.39) and RTS (0.33). The products stored at room temperature

showed higher % of acidity except for squash and nectar where acidity

was more at cold storage, but nectar had significantly higher acidity.

The interaction effects of products and storage periods showed

significant difference. In all the products higher % of acidity was

observed during 2nd month of storage compared to 3rd and 4th month.

There was significant decrease in acidity from 2nd month at each

successive month of storage.

The interaction effects of storage conditions and storage periods

showed significant differences. At room temperature and cold storage

acidity was significantly higher at 2nd month (0.63 %) compared to 1st

month (0.29) and further decreased during 3rd and 4th month of storage.

At room temperature squash and nectar showed higher acidity. In RTS

there was significant decrease in acidity and there was no change in

toffee. The interaction between products, storage periods and storage

conditions was also significant.

The interaction effects of products, storage periods and storage

conditions were significant. In squash there was an increase in acidity in

2nd month, decrease in 3rd month and no change in 4th month. In nectar

acidity % increased upto 3rd month in cold storage and during 4th month

there was no change. In RTS, acidity was higher in 1st month under cold

storage but significantly lower in 2nd and 3rd month with no change in 4th

month. There was decrease in acidity of toffee during 1st month with no

change on subsequent storage period.

Ascorbic acid

Data pertaining to ascorbic acid are presented in the table 7. The

results showed significant differences in ascorbic acid among products

and storage periods and the products distinctly differed with each other.

Toffee showed higher amount of ascorbic acid (6.72 mg/100g) followed

by squash (4.08 mg/100ml) and nectar (2.8 mg/100ml). Nectar and RTS

were at par. Storage conditions did not show any significant effect.

Ascorbic acid content was lower during 1st month storage (3.21

mg/100ml) but increased significantly during storage (4.14 mg/10 ml).

Storage periods 2nd, 3rd and 4th months were at par.


significant. At cold storage, squash and nectar showed higher amount of

ascorbic acid compared to room temperature. RTS showed higher

ascorbic acid content at room temperature. At room temperature nectar

and RTS were at par, with lower ascorbic acid, which differed

significantly with squash and toffee. In cold storage also similar trend

appeared but the products differed significantly among themselves with

the least in RTS (1.56 mg/ 100 ml).

The interaction effects of products and storage periods showed

significant differences. In squash and nectar higher ascorbic acid content

was recorded at 2nd and 4th month of storage compared to 1st month.

There was significant decrease in ascorbic acid in RTS with storage

period from 2nd month (2.2–1.74 mg/100ml). With toffee higher

ascorbic acid was found during 3rd and 4th month of storage.


between storage conditions and storage periods. At cold storage there

was significant increase in ascorbic acid by 4th month. At cold storage,

storage period 1st and 3rd months were at par. Similarly 3rd and 2nd

months were at par.

At room temperature the ascorbic acid was lower during 4th

month compared to 1st and 2nd months. The interaction between

products, storage periods and storage conditions were significant.

There was significant increase in ascorbic acid during 1st and 4th

months in squash, nectar and toffee at cold storage. In RTS however

there was significant decrease in ascorbic acid from 2nd month onwards

in cold storage compared to room temperature.

Sulphur dioxide

Data pertaining to sulphur dioxide are presented in table 8. There

were significant differences in sulphur dioxide among the products and

storage periods and different storage conditions. Squash contained

significantly higher ppm of SO2 (234.27 ppm) followed by toffee

(228.98 ppm), which were at par with each other. Nectar and RTS

contained lower amount of SO2 and differed significantly. There were

significant differences in SO2 of products among the storage periods.

The SO2 was least after 4 months of storage. It was on par with 3rd

month of storage and significantly lower than 1st and 2nd month of

storage.


significant. At room temperature RTS had lower amount followed by

nectar with lower ppm of SO2 which differed significantly from squash

and toffee which had higher ppm of SO2. In cold storage the products

differed significantly among themselves with the least in RTS

(67.2ppm) and highest in squash (320.8 ppm). There was a significantly

higher amount of SO2 in squash, nectar and toffee at cold storage

compared to RTS at room temperature.


between products and storage periods. Highest SO2 was found in nectar

and toffee during 1st month followed by 2nd which differed significantly.

Where as in squash higher SO2 content was found in 2nd month which

was significantly higher than that in 4th month. In RTS there was no

difference in SO2 content during 4th month of storage

The interaction between storage period and storage conditions

were significant. During 4th month lower SO2 content was observed at

both the storage conditions compared to 1st and 2nd month.

Interaction between products, storage periods and storage

conditions showed significant result. In general there was significantly

higher SO2 content in squash and toffee under cold storage at all storage

periods compared to that at room temperature. There was no such

difference in RTS and nectar, except for 1st month in nectar under cold

storage. In squash there was significant increase in SO2 content from 1st

to 2nd month of storage without further change under room temperature.

Where as under cold storage there was significant decrease from 1st to

2nd month without significant difference in later periods. In toffee at

room temperature there was significant decrease in SO2 upto 3rd month.

Where as under cold storage there was significant decrease upto 2nd

month. In RTS there was no difference in SO2 content in either storage

conditions or storage periods.

Reducing sugars

Data pertaining to reducing sugars are presented in table 9. There

were significant differences in reducing sugars among the products and

storage conditions and the products distinctly differed with each other.

Squash contained significantly higher % of sugars (34.26 %) followed

by toffee ( 26.09 %). Nectar and RTS contained lower amounts. The

reducing sugar content was significantly higher in products stored at

cold temperature (21.57 %) compared to that at room temperature

(18.36 %). There were significant difference in reducing sugars content

of products among the storage periods. The reducing sugars were least

after 4 months of storage (17.63 %). It was on par with the 3 months

storage and significantly lower than 1st and 2nd months of storage, which

were at par.


significant. At room temperature nectar and RTS were on par with lower

reducing sugar %, which differed significantly with squash and toffee,

which had higher reducing sugar %. In cold storage also similar trend

appeared but the products differed significantly among themselves with

the least in RTS (7.5%) and highest in squash (40%). There was a

significant increase in reducing sugars % in cold storage compared to

ambient condition in squash and nectar and there were no difference

with RTS and toffee in storage conditions.


between products and storage periods. In squash and toffee higher

percent of reducing sugar content was recorded at 2nd and 3rd months of

storage compared to 1st and 4th months. They were on par with each

other, whereas with nectar the reducing sugar content decreased during

2nd and 3rd month and with RTS there was no significant difference with

storage periods.


conditions and storage periods. The interaction between products,

storage periods and storage conditions were not significant.

Total sugars

Data pertaining to total sugars are presented in table 10. There

were significant differences in percent of total sugars among products

and storage periods and the products distinctly differed with each other.

Squash contained significantly higher % of sugars (75.4%) followed by

toffee (64.48%). Nectar and RTS contained lower. The total sugars

content was significantly higher in the products stored at room

temperature compared to that stored at cold storage. There were

significant differences in total sugars percent of products among the

storage periods. The total sugar percent was least after 4 months of

storage. It was significantly lower than 2nd and 3rd months of storage.


significant. At room temperature toffee and squash were at par with

higher sugar percent, which differed significantly with nectar and RTS,

which had lower sugar percent. In cold storage also the products showed

similar trend but the products differed significantly among themselves

with least in RTS (14.53%) and highest in squash (78.6%). There was

significant increase in total sugar percent in squash and nectar stored at

cold storage compared to ambient condition and with decrease in RTS

and toffee.


between products and storage periods. In all the products higher total

sugar content was recorded at 2nd month of storage. In squash 2nd and 3rd

months of storage were on par with each other, whereas with nectar 1st

and 3rd months were at par. 2nd and 3rd months of storage in RTS were at

par.

The interaction effects of storage periods and storage conditions

were significant. At room temperature and cold storage total sugars were

higher during 2nd month of storage. Total sugars were higher in squash,

nectar and lower in toffee at cold storage compared to room

temperature.

The interaction between products, periods and conditions were

significant. There was significant increase in total sugar content in

squash stored at room temperature (43.80 % - 58.42 %) and cold

storage. In nectar, RTS and toffee there was a significant decrease in

total sugar content in both the storage conditions with increase in storage

period. In toffee there was significant increase in total sugars during 2nd

and 3rd months of storage with further decrease during 4th month at room

temperature whereas under cold storage there was significant decrease in

total sugars from 1st to 4th months of storage. In nectar stored under cold

storage total sugars was higher during 2nd month of storage which

decreased significantly. There was significant decrease in total sugars in

nectar stored at room temperature with the storage period. Similar trend

was observed in RTS stored at room temperature and cold storage.

Organoleptic evaluation of stored custard apple products

The products developed from custard apple were stored at 2

different storage conditions for 4 months and each month they were

organoleptically assessed by a panel of 10 judges. The qualities

considered during the study were appearance, colour, flavour, taste and

overall acceptability. A maximum score of 5 was taken as standard for

considering the quality of the product.

Appearance

The data pertaining to appearance of the stored products are

presented in table 11. There were significant differences in appearance

among products and storage periods. Highest score for appearance was

seen for RTS stored at cold storage (4.55) followed by RTS at room

temperature (4.45). Least values were observed for toffee stored at room

temperature (4.13). Nectar and toffee stored at room temperature and

RTS were on par which were again on par with all other products except

for toffee at room temperature. Higher value for appearance was

observed during 1st month of storage (4.9) which decreased upon

storage. The products stored at cold storage obtained higher values for

appearance compared to that at room temperature.

Colour

Data for colour of the stored products are presented in table 12.

There were significant differences in colour among different products

and different storage periods. Higher values for colour were obtained for

RTS at cold storage (4.52) followed by Nectar and toffee stored at cold

storage (4.4). Lower values were observed for toffee at room

temperature (3.95). Nectar, RTS and toffee stored at cold storage were

on par. 1st month of storage period showed higher values for colour

which decreased gradually upon storage. All the products stored at cold

storage showed higher values for colour compared to that at ambient

temperature.

Flavour

Data pertained to flavour are presented in table 13. There were

significant differences in flavour among the products and storage

periods at different storage conditions. Higher values for flavour were

obtained for squash stored at cold storage (4.47) followed by RTS at

cold storage (4.37). Nectar stored at room temperature showed lower

values (3.85). Squash stored at cold storage was on par with RTS at cold

storage which was on par with squash and RTS stored at room

temperature. Higher values for flavour were obtained during 1st month

which was on par with 2nd month of storage. All the products stored at

cold storage showed higher values for flavour compared to that at

ambient temperature.

Taste

Data pertaining to taste are presented in table 14. The results

showed significant differences in taste among the products and storage

periods at different storage conditions. Squash stored at cold storage

showed higher value for taste (4.47) followed by RTS stored at cold

storage (4.4). Squash and RTS stored at cold storage and toffee stored at

room temperature were at par. RTS, squash, toffee stored at room

temperature and nectar, RTS, squash and toffee stored at cold storage

were on par. Higher values for taste were obtained during 1st month of

storage which decreased significantly upon storage.

All the products stored at cold storage showed higher values for

taste compared to that at room temperature.


Data pertaining to overall acceptability of the products are

presented in table 15. There were significant differences in overall

acceptability among the products, storage periods and different storage

conditions. Higher values for overall acceptability was obtained for RTS

stored at room temperature (4.57) followed by nectar and RTS at cold

storage (4.52). Squash, nectar, RTS and toffee stored at cold storage and

RTS at room temperature were on par. Higher values for overall

acceptability was obtained during 1st month which was on par with 2nd

month of storage. The overall acceptability of the products decreased

with the storage periods.

Microbial analysis

Microbiological studies like total plate count of bacteria, yeast

and mould count, coliform and E. coli count were carried out at 1st and

3rd month for the processed products stored at two different storage

periods to evaluate the safety and keeping quality of the products.

Total plate count (TPC)

Data pertaining to total plate count are presented in table 16.

Total plate count was carried out till 10-3 dilution level. There was a

significant difference in TPC among the products and storage conditions

at different storage periods. Squash contained significantly higher

number of bacteria [365], RTS contained lower number [15]. TPC in

nectar and toffee were on par. The TPC was significantly higher in

products stored at room temperature than at cold storage. There were

significant differences in TPC of products among the storage periods.

The TPC increased with the increase in storage periods in all the

products.


significant for all the dilutions. At room temperature TPC in nectar and

toffee were on par, which differed significantly with squash with high

number of TPC (510).

In cold storage also similar trend appeared and the products

differed significantly among themselves with least in RTS (5) and

highest in squash (220). At cold storage nectar and toffee were on par.

There was a significant increase in TPC in room temperature

compared to cold storage in all the products.


between products and storage periods. In squash, nectar and RTS higher

number of TPC was recorded during 1st month of storage compared to

2nd month whereas, in toffee the TPC decreased during 4th month of

storage compared to 2nd month.


conditions and storage periods. At room temperature and cold storage

higher number of TPC was found during 4th month of storage compared

to 2nd month of storage.

The interaction effects between products, storage periods and

storage conditions were not significant.

Yeast and mould count

Data pertaining to yeast and mould count are presented in table

17. Yeast and mould count was carried out till 10-3 dilution. There was a

significant difference in yeast and mould count among the products and

storage conditions at different storage periods. Squash contained

significantly higher number of yeast and moulds [480], RTS contained

lower number [27]. The yeast and mould count was significantly higher

in products stored at room temperature than cold storage. There were

significant differences in yeast and mould count of products among the

storage periods. The yeast and mould count increased with increase in

storage periods.


significant. At room temperature nectar and RTS were on par. Nectar

and toffee at room temperature were on par. All the products stored at

room temperature differed significantly with squash with high number

of count. In cold storage also similar trend appeared and the products

differed significantly among themselves with least in RTS (10) and

highest in squash (360). There was a significant increase in yeast and

mould count in all the products at room temperature compared to cold

storage.

There were significantly differences for the interaction effects

between products and storage periods. There was significant increase in

the growth of yeast and moulds with the storage period in all the

products.

The interaction effects between storage periods and storage

conditions were significant. Both the products stored at room

temperature and cold storage showed significant increase in yeast and

mould count with increase in storage periods.

The interaction effects between products, storage periods and

storage conditions showed significant difference.

Table – 1 : Physico – chemical characteristics of custard apple pulp and its products before storage.

Parameters Pulp Squash Nectar RTS Toffee

pH 5.62 4.26 3.74 3.34 -

TSS( Brix) 28 51 14 13 -

Acidity % 0.51 0.32 0.44 0.32 0.37

Ascorbic acid (mg/100 ml or 100 g)

9.22 6.96 2.32 2.32 9.15

Sulphurdioxide (ppm)

883.97 376 160 96 320

Reducing sugars (%)

20.75 42.83 20.5 14.16 58.16

Total sugars (%)

21.42 57.53 23.62 17.12 68.25

Table – 2 :Organoleptic characteristics of custard apple products before storage.

Attributes Squash Nectar RTS Toffee

Appearance 5 5 5 4.9

Colour 5 4.9 5 4.7

Flavour 5 5 4.6 4.8

Taste 5 4.9 4.6 4.8


5 5 4.9 4.7

Table – 3 : Microbiological characteristics of custard apple pulp and its products before storage.

Products Total plate count (CFU/ml or g sample)

Yeast and mould count(CFU/ml or g

sample)

Pulp 20 20

Squash 90 30

Nectar 10 10

RTS NIL NIL

Toffee 70 20

STORAGE STUDIES ON PROCESSED CUSTARD APPLE PRODUCTS Table 4 : pH of processed custard apple products.

Storage conditions

C1 3.54

C2 3.60

S.E 0.01

CD (P = 0.05) 0.04

Products

P1 4.01

P2 3.54

P3 3.15

S.E 0.01

CD (P = 0.05) 0.05

Storage periods

Pe1 3.75

Pe2 3.59

Pe3 3.49

Pe4 3.44

S.E 0.02

CD (P = 0.05) 0.06

Products x storage periods

Products – storage periods

P1 P2 P3

Pe1 4.22 3.70 3.33

Pe2 4.05 3.58 3.16

Pe3 3.92 3.46 3.11

Pe4 3.85 3.45 3.03

S.E 0.03

CD (P = 0.05) NS

pH of stored custard apple products Storage conditions x Storage periods

Storage conditions

Storage periods

C1 C2

Pe1 3.74 3.76

Pe2 3.54 3.64

Pe3 3.45 3.54

Pe4 3.42 3.46

S.E 0.03

CD (P = 0.05) NS

Products x storage conditions

Storage conditions products

C1 C2

P1 3.97 4.04

P2 3.51 3.58

P3 3.13 3.18

S.E 0.02

CD (P = 0.05) NS

Table 5: Total soluble solids of custard apple products (Brix)

Storage Conditions

C1 25.90

C2 26.36

S.E 0.03

CD (P = 0.05) 0.11

Products

P1 52.02

P2 13.37

P3 13.00

S.E 0.04

CD (P = 0.05) 0.13

Storage periods

Pe1 26.16

Pe2 26.27

Pe3 26.08

Pe4 26.00

S.E 0.05

CD (P = 0.05) 0.15

Products x Storage conditions

Products / Storage conditions C1 C2

P1 51.37 52.66

P2 13.33 13.41

P3 13.00 13.00

S.E 0.06

CD (P = 0.05) 0.19

Products x Storage periods

Products

Storage periods

P1 P2 P3

Pe1 51.50 14.00 13.00

Pe2 51.66 14.16 13.00

Pe3 52.00 13.25 13.00

Pe4 52.91 12.08 13.00

S.E 0.09

CD (P = 0.05) 0.27

Storage conditions x Storage periods

Storage periods / Storage conditions C1 C2

Pe1 26.00 26.33

Pe2 26.11 26.44

Pe3 25.83 26.33

Pe4 25.66 26.33

S.E 0.07

CD (P = 0.05) NS

Table 6 : Acidity of custard apple products (%)

Storage Conditions

C1 0.33

C2 0.37

S.E 0.002

CD (P = 0.05) 0.0083

Products

P1 0.25

P2 0.42

P3 0.34

P4 0.40

S.E 0.004

CD (P = 0.05) 0.0117

Storage periods

Pe1 0.33

Pe2 0.67

Pe3 0.24

Pe4 0.17

S.E 0.004

CD (P = 0.05) 0.0117



P1 0.23 0.28

P2 0.36 0.49

P3 0.34 0.33

P4 0.41 0.39

S.E 0.006

CD (P = 0.05) 0.016


Products

Storage periods

P1 P2 P3 P4

Pe1 0.28 0.25 0.41 0.38

Pe2 0.47 0.92 0.67 0.64

Pe3 0.15 0.35 0.15 0.32

Pe4 0.12 0.19 0.12 0.26

S.E 0.008

CD (P = 0.05) 0.023



Pe1 0.29 0.37

Pe2 0.63 0.71

Pe3 0.25 0.23

Pe4 0.17 0.17

S.E 0.006

CD (P = 0.05) 0.016

Table 7 : Ascorbic acid of custard apple products (mg/100ml or 100g sample)

Storage Conditions

C1 3.92

C2 3.91

S.E 0.0462

CD (P = 0.05) NS

Products

P1 4.08

P2 2.80

P3 2.07

P4 6.72

S.E 0.0654

CD (P = 0.05) 0.1845

Storage periods

Pe1 3.21

Pe2 4.20

Pe3 4.12

Pe4 4.14

S.E 0.0654

CD (P = 0.05) 0.1845



P1 3.87 4.30

P2 2.45 3.15

P3 2.58 1.56

P4 6.79 6.65

S.E 0.09

CD (P = 0.05) 0.26


Products

Storage periods

P1 P2 P3 P4

Pe1 3.00 2.22 2.20 5.45

Pe2 4.64 3.19 2.32 6.65

Pe3 4.06 2.90 2.03 7.50

Pe4 4.64 2.90 1.74 7.28

S.E 0.013

CD (P = 0.05) 0.37



Pe1 2.49 3.94

Pe2 4.92 3.48

Pe3 4.48 3.76

Pe4 3.79 4.48

S.E 0.09

CD (P = 0.05) 0.26

Table 8 : Sulphur dioxide of custard apple products (ppm)

Storage Conditions

C1 124.06

C2 189.58

S.E 2.5301

CD (P = 0.05) 7.1412

Products

P1 234.27

P2 99.20

P3 64.85

P4 228.98

S.E 3.5781

CD (P = 0.05) 10.0992

Storage periods

Pe1 178.22

Pe2 163.22

Pe3 147.67

Pe4 138.18

S.E 3.5781

CD (P = 0.05) 10.0992



P1 147.75 320.80

P2 88.80 109.60

P3 62.50 67.20

P4 197.22 260.73

S.E 5.06

CD (P = 0.05) 14.28


Products

Storage periods

P1 P2 P3 P4

Pe1 241.00 124.80 76.80 270.30

Pe2 244.80 104.00 64.00 240.10

Pe3 227.30 96.00 59.40 208.00

Pe4 224.00 72.00 59.20 197.52

S.E 7.15

CD (P = 0.05) 20.19

Storage Conditions x Storage periods

Storage periods / Storage conditions

C1 C2

Pe1 134.90 221.55

Pe2 136.00 190.45

Pe3 116.95 178.40

Pe4 108.42 167.93

S.E 5.06

CD (P = 0.05) 18.97

Table 9 : Reducing sugars of custard apple products (%)

Storage Conditions

C1 18.36

C2 21.57

S.E 0.5569

CD (P = 0.05) 1.5719

Products

P1 34.26

P2 11.37

P3 8.15

P4 26.09

S.E 0.7876

CD (P = 0.05) 2.2230

Storage periods

Pe1 20.83

Pe2 21.91

Pe3 19.50

Pe4 17.63

S.E 0.7876

CD (P = 0.05) 2.2230



P1 28.46 40.05

P2 9.58 13.15

P3 8.81 7.50

P4 26.59 25.60

S.E 1.11

CD (P = 0.05) 3.14


Products

Storage periods

P1 P2 P3 P4

Pe1 30.99 16.89 10.86 24.58

Pe2 40.51 8.14 7.73 31.26

Pe3 35.31 7.82 6.77 28.12

Pe4 30.22 12.64 7.26 20.43

S.E 1.57

CD (P = 0.05) 4.44



Pe1 19.79 21.86

Pe2 20.34 23.47

Pe3 18.21 20.79

Pe4 15.09 20.18

S.E 1.11

CD (P = 0.05) NS

ORGANOLEPTIC EVALUATION OF STORED CUSTARD

APPLE PRODUCTS Table 11 : Appearance of custard apple products

Products

P1 4.22

P2 4.25

P3 4.30

P4 4.37

P5 4.45

P6 4.55

P7 4.12

P8 4.42

S.E 0.1184

CD (P = 0.05) 0.2321

Storage periods

Pe1 4.90

Pe2 4.65

Pe3 3.78

Pe4 4.01

S.E 0.0837

CD (P = 0.05) 0.1641

Storage periods x products

Products Storage periods

P1 P2 P3 P4 P5 P6 P7 P8

Pe1 5.00 5.00 4.90 5.00 4.90 5.00 4.70 4.70

Pe2 4.40 4.50 4.40 4.70 5.00 4.90 4.60 4.70

Pe3 3.60 3.80 4.10 3.90 3.90 3.70 3.40 3.90

Pe4 3.90 3.70 3.80 3.90 4.00 4.60 3.80 4.40

S.E 0.2369

CD

(P=0.05)

0.6102

P1 = Squash at room temperature

P2 = Squash at cold storage

P3= Nectar at room temperature

P4 = Nectar at cold storage

P5 = RTS at room temperature

P6 = RTS at cold storage

P7 = Toffee at room temperature

P8 = Toffee at cold storage

Pe1 = 1st month of storage

Pe2 = 2nd month of storage

Pe3 = 3rd month of storage

Pe4 = 4th month of storage

Table 12 : Colour of custard apple products

Products

P1 4.20

P2 4.27

P3 4.30

P4 4.40

P5 4.32

P6 4.52

P7 3.95

P8 4.40

S.E 0.1235

CD (P = 0.05) 0.2421

Storage periods

Pe1 4.8

Pe2 4.61

Pe3 3.78

Pe4 3.98

S.E 0.0874

CD (P = 0.05) 0.1712



P1 P2 P3 P4 P5 P6 P7 P8

Pe1 5.00 5.00 4.90 4.80 4.90 5.00 4.30 4.50

Pe2 4.90 4.80 4.50 4.70 4.50 4.60 4.30 4.60

Pe3 3.30 3.60 3.90 4.00 3.80 4.10 3.50 4.10

Pe4 3.60 3.70 3.90 3.90 4.10 4.40 3.70 4.40

S.E 0.2471

CD

(P=0.05)

0.6364













Table 13 : Flavour of custard apple products

Products

P1 4.32

P2 4.47

P3 3.85

P4 4.12

P5 4.30

P6 4.37

P7 4.02

P8 4.20

S.E 0.1234

CD (P = 0.05) 0.2418

Storage periods

Pe1 4.66

Pe2 4.60

Pe3 3.66

Pe4 3.91

S.E 0.0873

CD (P = 0.05) 0.1710



P1 P2 P3 P4 P5 P6 P7 P8

Pe1 5.00 4.90 4.60 4.60 4.50 4.40 4.60 4.70

Pe2 5.00 5.00 4.40 4.40 5.00 4.70 4.20 4.10

Pe3 3.50 3.90 3.20 3.70 3.60 3.90 3.70 3.80

Pe4 3.80 4.00 3.20 3.80 4.10 4.50 3.60 4.20

S.E 0.2468

CD

(P=0.05)

0.4837













Table 14 : Taste of custard apple products

Products

P1 4.30

P2 4.47

P3 4.10

P4 4.32

P5 4.25

P6 4.40

P7 4.00

P8 4.35

S.E 0.1235

CD (P = 0.05) 0.2420

Storage periods

Pe1 4.63

Pe2 4.50

Pe3 3.81

Pe4 4.15

S.E 0.0873

CD (P = 0.05) 0.1711



P1 P2 P3 P4 P5 P6 P7 P8

Pe1 4.90 5.00 4.40 4.70 4.70 4.60 4.10 4.70

Pe2 4.80 4.80 4.30 4.60 4.30 4.50 4.30 4.40

Pe3 3.60 3.90 3.60 3.90 3.70 3.90 3.80 4.10

Pe4 3.90 4.20 4.10 4.10 4.30 4.60 3.80 4.20

S.E 0.2469

CD

(P=0.05)

NS













Table 15 : Overall acceptability of custard apple products

Products

P1 4.30

P2 4.47

P3 4.35

P4 4.52

P5 4.57

P6 4.52

P7 4.20

P8 4.47

S.E 0.1074

CD (P = 0.05) 0.2106

Storage periods

Pe1 4.88

Pe2 4.75

Pe3 3.88

Pe4 4.18

S.E 0.0760

CD (P = 0.05) 0.1489



P1 P2 P3 P4 P5 P6 P7 P8

Pe1 5.00 5.00 4.90 4.80 5.00 4.90 4.70 4.80

Pe2 4.90 4.90 4.70 4.80 4.90 4.70 4.50 4.60

Pe3 3.50 3.90 4.10 4.10 4.00 3.80 3.60 4.10

Pe4 3.80 4.10 3.70 4.40 4.40 4.70 4.00 4.40

S.E 0.2149

CD

(P=0.05)

0.4212






Storage conditions x Products x Storage periods

C1 C2

Pe1 Pe2 Pe3 Pe4 Pe1 Pe2 Pe3 Pe4

P1 4.20 3.98 3.98 3.83 4.24 4.12 3.95 3.88

P2 3.70 3.54 3.40 3.42 3.70 3.62 3.52 3.49

P3 3.32 3.12 3.07 3.03 3.34 3.20 3.15 3.03

S.E 0.05

CD

(P=0.05)

NS

NS = Non significant

C1 = Room temperature

C2 = Cold storage

P1 = Squash

P2 = Nectar

P3 = RTS






C1 C2


P1 51.00 51.16 51.33 52.00 52.00 52.16 52.66 53.83

P2 14.00 14.16 13.16 12.00 14.00 14.16 13.33 12.16

P3 13.00 13.00 13.00 13.00 13.00 13.00 13.00 13.00

S.E 0.13

CD

(P=0.05)

NS



C2 = Cold storage

P1 = Squash

P2 = Nectar

P3 = RTS






C1 C2


P1 0.24 0.38 0.19 0.12 0.32 0.57 0.12 0.12

P2 0.12 0.83 0.32 0.19 0.38 1.02 0.38 0.19

P3 0.38 0.70 0.19 0.12 0.44 0.64 0.12 0.12

P4 0.42 0.64 0.32 0.26 0.35 0.64 0.32 0.26

S.E 0.0118

CD

(P=0.05)

0.0332


C2 = Cold storage

P1 = Squash

P2 = Nectar

P3 = RTS

P4 = Toffee






C1 C2


P1 1.56 5.80 4.64 3.48 4.44 3.48 3.48 5.80

P2 1.11 3.48 2.90 2.32 3.33 2.90 2.90 3.48

P3 2.20 2.90 2.90 2.32 2.20 1.74 1.16 1.16

P4 5.11 7.5 7.50 7.07 5.80 5.80 7.50 7.50

S.E 0.1849

CD

(P=0.05)

0.5218



C2 = Cold storage

P1 = Squash

P2 = Nectar

P3 = RTS

P4 = Toffee






C1 C2


P1 110.81 160.00 160.20 160.00 371.20 329.60 294.40 288.00

P2 102.40 96.00 89.60 67.20 147.20 112.00 102.40 76.80

P3 70.40 64.00 58.00 57.60 83.20 64.00 60.80 60.80

P4 256.00 224.00 160.00 148.90 284.60 256.20 256.20 246.15

S.E 10.1205

CD

(P=0.05)

28.5649


C2 = Cold storage

P1 = Squash

P2 = Nectar

P3 = RTS

P4 = Toffee






C1 C2


P1 23.98 33.52 30.44 25.90 38.00 47.50 40.18 34.54

P2 17.50 7.52 7.05 6.28 16.28 8.76 8.59 19.00

P3 12.60 7.86 6.52 8.26 9.12 7.60 7.03 6.26

P4 25.11 32.47 28.86 19.94 24.06 30.05 27.38 20.92

S.E 2.22

CD

(P=0.05)

NS



C2 = Cold storage

P1 = Squash

P2 = Nectar

P3 = RTS

P4 = Toffee





MICROBIOLOGICAL EVALUATION OF STORED CUSTARD APPLE PRODUCTS

Table 16 : Total plate count of custard apple products

Storage conditions CFU/ml or g sample

C1 160

C2 73

S.E 0.2932

CD (P = 0.05) 0.8446

Products

P1 365

P2 45

P3 15

P4 40

S.E 0.446

CD (P=0.05) 1.1944

Storage periods

Pe1 86

Pe2 146

S.E 0.2932

CD (P=0.05) 0.8446

Products x storage conditions

P1 C1 510

P1 C2 220

P2 C1 50

P2 C2 40

P3 C1 25

P3 C2 5

P4 C1 50

P4 C2 30

S.E 0.5863

CD (P=0.05) 1.6892

P1 Pe1 270

P1 Pe2 460

P2 Pe1 20

P2 Pe2 70

P3 Pe1 5

P3 Pe2 25

P4 Pe1 50

P4 Pe2 30

S.E 0.5863

CD (P=0.05) 1.6892

C1 Pe1 127

C1 Pe2 190

C2 Pe1 45

C2 Pe2 102

S.E 0.4146

CD (P=0.05) NS

* CD (P – 0.01)

Table 17 : Yeast and Mould count of custard apple products

Storage conditions CFU/ml or g sample

C1 200

C2 122

S.E 0.3187

CD (P = 0.05) 0.9182

Products

P1 480

P2 57

P3 27

P4 80

S.E 0.4507

CD (P=0.05) 1.2985

Storage periods

Pe1 72

Pe2 250

S.E 0.3187

CD (P=0.05) 0.9182

P1 C1 600

P1 C2 360

P2 C1 45

P2 C2 70

P3 C1 45

P3 C2 10

P4 C1 110

P4 C2 50

S.E 0.6374

CD (P=0.05) 1.8363

P1 Pe1 250

P1 Pe2 710

P2 Pe1 25

P2 Pe2 90

P3 Pe1 5

P3 Pe2 50

P4 Pe1 10

P4 Pe2 150

S.E 0.6374

CD (P=0.05) 1.8363

Storage conditions x storage periods

C1 Pe1 85

C1 Pe2 315

C2 Pe1 60

C2 Pe2 185

S.E 0.4507

CD (P=0.05) 1.2985

Table 10 : Total sugars of custard apple products (%)

Storage conditions

C1 43.33

C2 42.39

S.E 0.2408

CD (P = 0.05) 0.6797

Products

P1 53.79

P2 16.95

P3 14.61

P4 64.48

S.E 0.3406

CD (P = 0.05) 0.9613

Storage periods

Pe1 30.84

Pe2 50.22

Pe3 46.99

Pe4 43.39

S.E 0.3406

CD (P = 0.05)


Storage conditions

products

C1 C2

P1 52.21 58.60

P2 13.00 20.90

P3 14.70 14.53

P4 73.42 14.53

S.E 0.48

CD (P = 0.05) 1.35


Products

Storage periods

P1 P2 P3 P4

Pe1 52,71 16,74 14.27 52.65

Pe2 55.48 19.24 16.65 76.53

Pe3 52.32 16.88 16.11 69.76

Pe4 54.75 14.96 11.43 58.98

S.E 0.68

CD (P = 0.05) 1.92


Storage conditions

Storage periods

C1 C2

Pe1 32.46 29.22

Pe2 50.11 50.34

Pe3 47.77 46.21

Pe4 42.99 43.80

S.E 0.48

CD (P = 0.05) 1.35



C2 = Cold storage

P1 = Squash

P2 = Nectar

P3 = RTS

P4 = Toffee






C1 C2


P1 43.80 55.07 55.56 58.42 35.62 41.90 41.90 45.00

P2 17.20 13.70 11.55 9.57 16.28 24.78 22.22 20.35

P3 15.11 15.11 15.00 12.12 13.44 17.14 16.82 10.75

P4 53.75 55.50 55.60 53.85 57.56 54.57 53.93 49.11

S.E 0.96

CD

(P=0.05)

2.71



C2 = Cold storage

P1 = Squash

P2 = Nectar

P3 = RTS

P4 = Toffee






C1 (CFU/ml or g sample) C2 (CFU/ml or g sample)

Pe1 Pe2 Pe3 Pe4

P1 420 600 120 320

P2 20 80 20 60

P3 10 40 0 10

P4 60 40 40 20

S.E O.8292

CD(P=0.05) NS



C2 = Cold storage

P1 = Squash

P2 = Nectar

P3 = RTS

P4 = Toffee




C1 (CFU/ml or g sample) C2 (CFU/ml or g sample)

Pe1 Pe2 Pe3 Pe4

P1 300 900 200 520

P2 10 80 40 100

P3 10 80 0 20

P4 20 200 0 100

S.E O.9014

CD(P=0.05) 2.5969



C2 = Cold storage

P1 = Squash

P2 = Nectar

P3 = RTS

P4 = Toffee



CHAPTER – V

DISCUSSION

Custard apple products like squash, nectar, RTS and toffee were

prepared from preserved custard apple pulp and stored at room

temperature and cold storage for a period of 4 months to study the

stability of the products. The products were analysed every month for

physico-chemical and organoleptic qualities. The microbioligical safety

of these products were also analysed.

The results obtained for custard apple pulp and processed custard

apple products are discussed in this chapter under the following

headings.

5.1 Physico-chemical characteristics of custard apple pulp and its

products

5.2 Storage studies of processed custard apple products

5.3 Organoleptic evaluation of custard apple products

5.4 Microbiological evaluation of custard apple products

5.5 Overall review

5.1 Physico-chemical characteristics of custard apple pulp and its

products

pH

The pH of all the products prepared from the stored pulp was

lower compared to the pulp. The pH of the stored pulp was 5.62. The

initial pH of the products prepared were squash 4.26, nectar 3.74 and

RTS 3.34. The decrease in pH of the products may be attributed to the

added citric acid. Decrease in pH of nectar due to added citric acid was

reported by Teotia et al. (1997) and Aruna et al. (1997) in case of

papaya.


The TSS of the stored pulp was 28. Initial TSS reading of the

squash was found to be higher (51), which is due to added sugars in

squash that increased the TSS value. The lower TSS value in nectar

(14) and RTS (13) is due to the dilution of the products. However,

TSS of the products were in accordance with the FPO specifications.

Acidity

Acidity was found to be lower in all the products prepared

compared to the stored pulp. This may be due to the dilution of the

products during processing. The acidity of the pulp preserved was

0.51%. The acidity of the products were squash 0.32%, nectar 0.44%,

RTS 0.32% and toffee 0.37%.

Ascorbic acid

Ascorbic acid content was found to be lower in all the products

prepared compared to the stored pulp. The reduction in ascorbic acid

may be attributed to its destruction by oxidation or heat during

processing. Similar observations were reported by Teotia et al. (1997)

for muskmelon.

Sulphurdioxide

Custard apple pulp was stored by the addition of 1500 ppm of

potassium metabisulphite. The SO2 content of the pulp after a storage

period of 6 months was found to be 884 ppm which was within the FPO

specifications. SO2 content of the products prepared from the stored pulp

were lower compared to the pulp and varied depending upon the

product. The decrease in the SO2 content may be attributed to the

dilution of the product with water or due to varying levels of pulp used

during preparation of the products or due to its destruction by heat. The

initial SO2 content of squash was 376 ppm and nectar 160 ppm which

were higher than the FPO specifications which allows 350 ppm and 100

ppm of SO2 in squash and nectar respectively. SO2 content of RTS was

within the specified limit (96 ppm). Reduction in SO2 content in pulp

upon storage was reported by Teotia et al. (1997) for muskmelon.

Hence, it can be expected that the marginally higher levels of SO2 in

squash and nectar will be reduced to conform to the FPO specifications.

Total sugars and Reducing sugars

The total sugar content of the stored pulp was 21.42%. The total

sugar content of the products prepared were higher than that of the

stored pulp except for RTS. The high sugar content is due to the added

sugar. Though sugar was added in RTS, total sugars was low due to

dilution with water. The initial reducing sugar content of the pulp was

20.75% which increased in all the products prepared except for RTS. A

similar trend was reported by Ranote et al. (1993) for mango pulp.

5.2 Storage studies of processed custard apple products

The products squash, nectar, RTS and toffee prepared from the

stored pulp were stored both at cold storage and room temperature for a

period of 4 months to determine their keeping quality and acceptability.

The products were analysed every month for physico-chemical and

bimonthly for microbiological characteristics to evaluate their stability.

pH

Slight decline in pH of all the products was observed during 4

months of storage. Decrease in pH of the products is due to the added

citric acid during processing. The results obtained are in agreement with

that of Aruna et al. (1997) for papaya products and Chahal et al. (1999)

for water melon juice.


The TSS of the products stored for 4 months showed varying

results. There was a slight increase in TSS in squash from 51 to 52.9

after 4 months of storage. TSS of squash stored at cold storage was

higher than that at room temperature. Kirpal Singh and Mathur (1953)

observed an increase in TSS in cashew apples under cold storage. Slight

increase of TSS in case of lemon juices after a storage period of 7

months was reported by Palaniswamy et al. (1974).

The TSS of nectar decreased from (14 to 12) upon storage.

Decrease in TSS is may be due to settling down of some soluble

colloidal solids, incipient fermentation and other chemical reactions of

sugar in presence of acid during storage. Decrease in TSS of Kiwi fruit

squashes were observed by Thakur et al. (1998).

There was no appreciable change in TSS of RTS upon storage.

This is in agreement with the results of Jain et al. (1986) for phalsa,

kaphal and litchi squashes and Teotia et al. (1997) for muskmelon RTS.

Acidity

In squash and nectar the acidity was found to be decreasing with

increase in storage periods inspite of a slight decline in pH, the reason

for which is unknown. However, in RTS and toffees the acidity was

higher after 4 months of storage. Increase in acidity in toffees may be

attributed to loss of moisture from the surface of toffees during storage.

These results were similar to that obtained by Kaushal et al. (2001) for

apple pomace toffees. Increase in acidity with decline in pH was

observed in RTS upon storage. Similar results were also reported by

Palaniswamy et al. (1974) for lemon juices and Chahal et al. (1999) for

watermelon juices.

Ascorbic acid

Ascorbic acid showed a continuous decrease in all the products as

the storage period advanced except for a slight increase in nectar. The

loss varied between 6.96 to 4.08 mg/100 ml juice in squash, 2.32 to

12.07 mg/100 ml juice in RTS and from 9.15 to 6.72 mg/100 g sample

in toffee. Similar changes were reported by Palaniswamy et al. (1974)

for lemon juices and squashes, Teotia et al. (1997) for muskmelon RTS

and Aruna et al. (1997) for papaya products.

Loss of ascorbic acid was found to be more in products stored at

room temperature compared to that at cold storage. The results obtained

are in agreement with that of Sahni et al. (1989) for mango nectar.

Similar results were observed by Chahal et al. (1998) for water

melon juice and Tiwari et al. (2001) for Guava RTS. Decreasing levels

of ascorbic acid may be due to its gradual oxidation upon storage.

Sulphur dioxide

There was a gradual decrease in SO2 content of all the products

upon storage. The loss varied between 376 ppm to 234 ppm in squash,

160 to 99 ppm in nectar, 96 to 65 ppm in RTS and 320 to 229 ppm in

toffee. Loss of SO2 was more in products stored at room temperature

compared to that at cold storage. The SO2 content of all the products

stored at room temperature and cold storage were below the FAO

standards except for a slight higher SO2 content in nectar stored at cold

storage (109 ppm). Similar results were put forth by Roy et al. (1979)

for bael fruit products and Kalra et al. (1984) for guava nectar.

Reducing sugars

A decrease in reducing sugar content was observed in squash and

toffee upon storage against increasing reducing sugars upon storage as

reported by Palaniswamy et al. (1974) for lemon juices and squashes,

Teotia et al. (1997) for muskmelon RTS and Kaushal et al. (2001) for

apple pomace toffees.

A decrease in reducing sugar content of papaya toffee and nectar

was reported by Aruna et al. (1997). Decrease in reducing sugars is

because inversion might not have occured in the products.

Total sugars

Slight decrease in total sugars were observed in all the products

with increase in storage period. Similar results were observed by Thakur

et al. (1998) for Kiwi squash and Chahal et al. (1999) for watermelon

juice. The low total sugar content could be due to dilution of the

product. The results of Teotia et al. (1997) for muskmelon RTS and

Tiwari et al. (2001) for guava beverage showed that total sugars were

unchanged upon storage. The total sugar content of the products stored

at room temperature were higher compared to that at cold storage.

5.3 Organoleptic evaluation of custard apple products

All the processed custard apple products were initially evaluated

organoleptically by a panel of 10 judges for their appearance, colour,

flavour, taste and overall acceptability. A maximum score of 5 was

taken as standard for considering the quality of the products. All the

products ranked excellent in all the quality characteristics.

There was a considerable decrease in sensory mean score for

taste, colour, flavour and overall acceptability during storage. The

sensory mean score for each attribute was highest on the day of

preparation which decreased with passage of time. Similar opinion was

put forth by Palaniswamy et al. (1974) for lemon squashes. Decrease in

flavour upon storage may be due to loss of volatile aromatic substances

responsible for flavour. A similar opinion was put forward by Thakur et

al. (1998) in case of kiwi squash. Decrease in colour of the products

may be due to browning reactions in the products. This is in accordance

with the result of Thakur et al. (1998) for kiwi squash. The overall

acceptability of the products decreased as the storage period increased.

Organoleptic evaluation of the processed products remained more

acceptable for products stored at low temperature compared to that at

room temperature. The products stored at room temperature were

acceptable till third month of storage. However, the products stored at

cold storage showed an overall acceptability upto four months of

storage. Retention of colour, taste, flavour and appearance were better in

all the products stored at low temperature indicating that low

temperature storage conditions are better in improving the shelf life

stability of the products. These results are similar with the earlier

observations of Jain et al. (1986) for phalsa, kaphal and litchi squashes,

Chauhan et al. (1993) for fruit juice beverages from pulp and Vijay

Sethi (1995) for mango pulp. However, the products stored at ambient

temperature were also acceptable during the 4 month storage period.

5.4 Microbiological evaluation of custard apple products

Microbial analysis of the stored pulp after a storage period of 6 months

showed very less or negligible total bacterial count and yeast and mould

count. Preservation of pulp at lower temperature of 5C retarded the

growth of bacteria. A similar opinion was expresssed by Rouhangiz

Hayati et al. (1992) for RTS beverages from preserved guava pulp.

However, initial microbial analysis of squash and Toffee revealed

either higher microbial count than the pulp which were also negligible

which might be due to improper handling. Increase in microbial growth

with the storage period was observed in all the products but the increase

was more in the products stored at room temperature compared to that

stored at cold storage indicating the effectiveness of low temperature

storage on the retardation of microbial growth. However, the increase in

microbial growth were within the permissible level. Application of heat

during processing irrespective of holding time reduced the microbial

load. A similar opinion was given by Das et al. (1992) in case of apple

juice, Ghorai (1996) for Kinnow mandarin juice and Supriya Langthasa

et al. (2001) for apple pulp. As the microbial growth was within control

even in the products stored at room temperature, the products can well

be stored at ambient temperature.

Overall review

Pulp was extracted from custard apples during the glut season

and stored for a period of 6 months by addition of 1500 ppm of KMS

and after 6 months various products were prepared and assessed for their

keeping quality at both room temperature and cold storage.

It may be possible for the industries to prepare custard apple pulp

for a few months during the peak season and subsequently utilize it for

products preparation. With that assumption, custard apple pulp was

stored for approximately 6 months before using it for product

preparation. The products were further stored for 4 months to determine

their keeping quality and acceptability.

Physico-chemical, microbial and organoleptic evaluation of the

stored pulp and the products prepared from the stored pulp during

different storage periods indicated that the products could be stored for

at least 4 months without deterioration. Cold storage or low temperature

storage of the products is preferred but in areas where low temperature

facility is not available the product should be stored in dark avoiding

direct exposure to heat and sunlight which may lead to undesirable

changes in the product.

The custard apple products are novel and could be far cheaper.

They could easily find market as custard apple is a seasonal fruit. Cost

of production could not be compared directly as no such products

prepared from custard apple are available in the market at present.

Compared to the products processed from other fruits custard apple

products are far cheaper and the lower cost of production is attributable

to the low cost of basic raw material.

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