Effects of the Addition of Fermented Sorghum or Distilled...

Journal of Food and Drug Analysis, Vol. 20, No. 2, 2012, Pages 539-546

539

doi:10.6227/jfda.2012200216

Effects of the Addition of Fermented Sorghum or Distilled Fermented Sorghum on the Flavor and

Quality of Sorghum SpiritsHUNG-TANG LAI1, JIAN-sHING LEE1, TUNG-HsI YU2 AND CHI-YUE CHANG1*

1. Department of Bioindustry Technology, Da-Yeh University, No.168 University Rd., Dacun, Changhua, Taiwan, R.O.C. 2. Department of Hospitality Management, Hungkuang University, Taiwan, R.O.C.

(Received: December 17, 2010; Accepted: June 9, 2011)

ABsTRACT

This study investigated the use of third time fermented sorghum and distilled fermented sorghum for the production of sorghum spirits made by solid fermentation and solid distillation. The results indicated that higher yield of alcohol was obtained in groups with 5%, 10% and 15% fermented sorghum addition, slightly higher than that of the control group. With regard to distilled fermented sorghum, the alcohol yields of groups with 5%, 10%, 15% and 20% distilled fermented sorghum addition were higher than that of the control group. The group with 20% distilled fermented sorghum produced the best results. There was no significant difference in acidity among all of the experimental groups. Groups with fermented sorghum or distilled fermented sorghum had higher levels of total esters than that of the control group, indicating that the addition of either fermented sorghum or distilled fermented sorghum contributes to the increase of fragrance-producing esters in sorghum spirits. Flavor tests showed that spirits produced by adding 5% fermented sorghum had a stronger fragrance and better taste than those of the control group. Spirits produced by adding 5 - 20% distilled fermented sorghum also had better taste and aroma than those of the control group spirits. These results indicated that addition of 5 - 20% distilled fermented sorghum to the newly cooked sorghum improved the quality of the produced sorghum spirits. The major fragrance-producing components found in the sorghum spirits were ethyl acetate and ethyl lactate. Other fragrance-producing components include acet-aldehyde, iso-butyraldehyde, 2-butanol, n-propanol, iso-butanol, n-butanol, 2-methyl-1-butanol, 3-methyl-1-butanol, ethyl succinate and 2-phenyl ethanol. The addition of fermented sorghum to the newly cooked sorghum was successful in increasing both the higher alcohol (n-propanol, 2-butanol, iso-butanol, n-butanol, 2-methyl-1-butanol and 3-methyl-1-butanol) yield and fragrance. In addition, spirits prepared by adding 5% fermented sorghum had the best proportion of ethyl acetate and ethyl lactate; they also produced a mild fragrance. The overall taste performance of these spirits was better than those of spirits with 10%, 15% or 20% fermented sorghum, or of the control group spirits. Furthermore, the higher alcohol content and ethyl lactate did not vary significantly among the experimental groups with 5 - 20% fermented sorghum. Compared to the control group, groups with 5, 10, 15 and 20% distilled fermented sorghum addition had better values in higher alcohol content as well as the proportion of ethyl acetate and ethyl lactate.

Key words: sorghum spirits, fermented sorghum, distilled fermented sorghum, solid fermentation, solid distillation

INTRoDUCTIoN

Solid fermentation and distillation of sorghum play important roles in Taiwan’s liquor production(1). The sorghum grains are cooked whole at high pressure, cooled, mixed with koji, and moved into inox (stainless steel) containers for initial fermentation. After distillation, fermented sorghum becomes distilled fermented sorghum. To obtain the final sorghum spirit, distilled fermented sorghum is further

fermented and distilled three times(2,3). Distilled alcoholic beverages are unique because they are produced by distilling alcohols that have already been fermented; this is done to obtain a very high alcohol concentration(4). Sorghum spirits, also known as liqueur or white spirits, are among the most popular distilled alcoholic beverages(5-8). In the manufac-turing of sorghum spirits, koji is often used as the source of fermenting microoganisms. With improvements over time, many different kinds of koji have been developed. On the basis of its consistency, koji can be classified as solid or liquid. Solid koji, major koji and minor koji can be distinguished

* Author for correspondence. Tel: +886-04-8511888 ext. 2283; Fax: +886-04-8511322; E-mail: [email protected]

Journal of Food and Drug Analysis, Vol. 20, No. 2, 2012

540

based on their shape and size. The microorganisms present in major koji are fungi, bacteria and yeasts, while those present in minor koji are Rhizopus spp. and yeasts(9-12). The distilled fermented sorghum of sorghum spirits contains roughly 20% crude proteins and 25% total sugar, and is often used as feed for livestock(13) or as raw materials for growing edible fungi(14-17). Distilled fermented sorghum is also used to produce glycerol(18-21), vinegar(22-26) and protein(27-29). Consequently, researches related to the re-use of distilled fermented sorghum are rapidly increasing.(30) Studies on sorghum spirits have long been carried out in both Taiwan and China; researchers have discovered that the primary vola-tile components of the beverage include ethyl acetate, ethyl lactate, ethyl caproate and ethyl butyrate. Other important volatile components include: n-propanol, iso-amyl alcohol, iso-butanol, n-butanol, 2-methyl-1-butanol, 3-methyl-1-butanol and 2-phenyl ethanol(3,5,7,9,31-35,44). However, few studies have focused on applying fermented sorghum and distilled fermented sorghum to improve the quality and fragrance. This study explores the effect of adding different ratios of fermented sorghum and distilled fermented sorghum to a sorghum spirit during different stages of fermenta-tion and distillation. In particular, the effects of distilled fermented sorghum and fermented sorghum on the quality of sorghum spirits and their volatile fragrance are examined.

MATERIALs AND METHoDs

I. Materials

(I) Wheat: Hard white winter wheat was imported from the USA. The specifications of the wheat are as follows: specific value 750 g/L, starch value > 73%, water content < 13.5%, protein content < 13%, aflatoxins < 10 ppb, ochra-toxins < 5 ppb.

(II) Sorghum: Sorghum Taichung No. 5.(III) Fermented sorghum: The undistilled alcohol-

containing sorghum after the third fermentation.(IV) Distilled fermented sorghum: Distilled fermented

sorghum was obtained by distilling the fermented sorghum from (III).

II. Method

(I) Koji Used in Traditional Taiwanese Sorghum Spirits

Koji was made with 100% raw white wheat. After a suitable degree of crushing, 30% of rough powder particles (size > 16-mesh), 40% of medium powder particles (size between 16- and 35-mesh) and 30% of fine powder particles (size < 35-mesh) were each mixed respectively with water and other catalysts to achieve a concentration of 37 ± 1%. A compressor was then used to press the koji into a spherical shape, 25 cm in diameter and 9 cm in thickness, leaving a 1-inch circular hole in the middle. The weight of the raw koji was controlled at 5.2 ± 0.2 kg. The raw koji was then sent to

the fermentation room (in units of 4000) and placed in stacks for a month. The temperature was kept under 50°C. After preparation, the koji was stored for another 2 - 3 months, at which time it weighed about 3.0 ± 0.2 kg with water content of less than 15%. Before making the liquor, the koji was shredded into a powdered state.

(II) Test for Fermented Sorghum and Distilled Fermented Sorghum

Sorghum spirits were fermented 3 times and distilled 3 times. For this part of the experiment, fermented sorghum (5%, 10%, 15% and 20%) or distilled fermented sorghum (5%, 10%, 15% and 20%) was added to the 45-kg cooked sorghum and mixed with 2.7 kg (6%) of wheat koji. The product was placed in a 50-L fermentation barrel and sealed tightly using a PE bag to induce anaerobic fermentation at 28 - 35°C for 14 days.

(III) Distillation Test

Two-stage solid distillation was carried out on fermented sorghum obtained after fermentation, with the use of a small distillation machine (50 L). In the first distil-lation process, water vapor was used to distill the fermented sorghum, resulting in a liquid with 27 ± 2% alcohol content. In the second distillation process, the product from the first process was distilled for 1 h to produce a liquid that had an alcohol concentration of 62 ± 2%. The final product was used as the sorghum spirit in this experiment.

III. Content Analysis

(I) Fermented Sorghum and Distilled Fermented Sorghum

1. Water Content (36): Ten grams of sample were dried in an oven at 105°C for 5 h. The weight loss was measured. Water content was defined as weight loss/sample weight × 100%.

2. Acidity(37): Ten grams of sample was placed in a 200-mL volumetric flask and distilled water was added up to the 200 mL-mark along with 0.5 mL of toluene. The flask was placed in a cooler for 14 - 15 h and filtered using #1 filter paper (600 × 600 mm, Toyo Roshi Kaisha Ltd., Japan). The filtered solution was sampled and 10 mL was tested using phenolphthalein by titrating 0.1 N NaOH into the solution until the solution changed to a light pink color. The volume of NaOH consumed was then indicated by measuring the quantity of 0.1 N NaOH (mL) required for the titration of the 10-g sample.

3. Amino-Nitrogen(38): Ten milliliters of the same filtered solution used in the acidity test above was mixed with 10 mL of 20% formaldehyde (Merck, Germany) and allowed to settle for 15 min. Then 0.1 N NaOH was titrated into it until the color of solution changed to light pink and the amount of NaOH consumed was recorded. Assuming that 1 mL of NaOH consumption was equivalent to having 0.0014 g of


541

amino-nitrogen in the sample, the mass of amino-nitrogen present in the sample was determined and recorded based on 100 g of the sample.

4. Reducing Sugar in Fermented Sorghum(39): Ten grams of sample was placed into a 500-mL volumetric flask. Distilled water was added to the 500 mL-volume mark, and 20 mL of this newly diluted solution was sampled. Bertrand’s method was used to determine the quantity of reducing sugar and the result was expressed as a percentage.

5. Reducing Sugar in Distilled Fermented Sorghum(40): Same as III-(I)-4.

6. Alcohol Concentration(41): Five hundred milliliters of water was added to 200 g of the sample stored in a 1,000-mL conical flask. A continuous distillation system was used to heat and distill the bottle. A 200-mL volume flask was used to collect about 180 mL of the distilled liquid; water was then used to fill the flask to the 200 mL-mark. Then alcohol was determined by an alcohol concentration meter (DA310, Kyoto Electronics Manufacturing Co., Japan).

7. Determination of Total Sugar(42):A. Reducing Sugar after Decomposition: Ten grams

of the sample was placed in a 500-mL beaker, and 200 mL of the distilled water and 20 mL of HCl (density = 1.125) were added. The solution was heated and boiled in a water bath for 3 h and phenolphthalein was used as an indicator. NaOH (0.1 N) was added to the solution to neutralize it, and then the solution was transferred into a 500-mL volumetric flask. Distilled water was added to the 500 mL-volume mark and the solution was filtered through filter paper. Bertrand’s method was used on 20 mL of the filtered solution to detect the amount of glucose present and the result was expressed as a percentage.

B. Total Sugar Calculation: The total sugar content was calculated as follows: Total Sugar (%) = (reducing sugar after decomposition – reducing sugar before decomposition)% × 0.9. Reducing sugar before decomposition was determined as in III-(I)-4. The conversion coefficient between glucose and total sugar was 0.9.

(II) Sorghum Spirits Analysis

1. Acidity(37)

The acidity of the fermented sorghum was determined as in III-(I)-2.

2. Total Ester (expressed as ethyl acetate)(43)

The sample containing phenolphthalein after the acidity test was used, the volume was recorded as V. NaOH (0.1 N) was added to make up the volume of the solution to 50 mL, it was sealed for hydrolysis for 24 h. After hydrolysis, 0.1 N H2SO4 was added until the color of the solution became clear. The quantity of sulfuric acid used was recorded as A mL. NaOH (0.1 N) was then added to the solution until it changed to a light pink color; the volume used was recorded as B mL.

Total ester (g/100 mL)= [(50 + B – V) mL × F (NaOH) – A mL × F (H2SO4)]

× 100 mL/25 mL × 0.0088 g* mL of 0.1 N NaOH represents 0.0088 g of ethyl acetate

in the sample * F is the correction factor of NaOH / H2SO4 solution.

3. Volatile Content Analysis(44)

Qualitative and quantitative analyses of the volatile compounds of sorghum spirits were performed with gas chromatography, with a flame ionization detector. About 20 standard volatile compounds, as reported in previous studies to be present in sorghum spirits, were diluted using 62% alcohol solution to make 40 - 250 mg/L of standard solutions. Cyclohexanol was also added to the solution as the internal standard (100 g/L), and 1 μL of sorghum spirit was used for analysis. The retention times compared with standards were used for qualitative analysis of the individual compounds. In addition, the ratio of the peak area of the compounds and the area of cyclohexanol was used to calculate the quantity of volatile components. The gas chromatography analyzer used in this experiment was produced by Perkin Elmer, model Auto System-XL. The columns used were Chrompack CP-Wax 57CB 50-m, with inner diameter of 0.25 mm and a membrane thickness of 0.2 μm. Helium was used as carrier gas, with a split ratio of 1 : 15. The initial temperature of the oven was set at 40°C. It was increased at a rate of 3.5°C/min until it reached 200°C. The oven was then maintained at isothermal temperature for 12.5 min. The injector was kept at 200°C, the detector at 250°C and the quantity of injection was 1 μL.

4. Taste Test(45-47)

A percentage rating test was performed by 16 expe-rienced panelists for evaluation of sorghum spirits. The following criteria were used:

a. Color (20%), b. Fragrance (30%), c. Taste (50%).

VI. Statistical analysis

Statistical analysis was performed using an unpaired, two-tailed Student’s t-test and a p < 0.05 was considered significant. Data were expressed as mean ± SD.

REsULTs AND DIsCUssIoN

I. Comparison of Cooked Sorghums with Different Ratios of Fermented Sorghum and Distilled Fermented Sorghum

The general compositions of the starting materials used for producing sorghum spirits in this study were listed in Table 1. The addition of fermented sorghum or distilled fermented sorghum to the newly cooked sorghum led to the increases of water content and acidity in the cooked sorghum. When the added amount of fermented sorghum or distilled fermented sorghum were 20%, the acidity of the cooked sorghum increased by about 3.5 ± 0.5%. With the addition of more fermented sorghum or distilled fermented sorghum, the total sugar content decreased. When 20% of fermented sorghum or distilled fermented sorghum was added to the newly cooked sorghum, the total sugar content dropped from 37.7% to about 32.5%. No change was found in the content of


542

reducing sugars in all 3 groups. The alcohol presented in the starting materials were derived from the added fermented sorghum or distilled fermented sorghum. Cooked sorghum with 20% fermented sorghum contained about 1.04 ± 0.12% alcohol. The alcohol contents in all other groups were lower than 0.2%.

II. Content Analysis of Fermented Sorghum Before and After Distillation

As shown in Table 2, the water contents of the cooked sorghum with the addition of fermented sorghum or distilled fermented sorghum were higher than that of the control group. The water contents varied directly with the quantities

of fermented sorghum or distilled fermented sorghum added. The groups with the additions of fermented sorghum (Af, Bf, Cf and Df) had a higher degree of acidity than the control group. The acidity was directly related to the quantity of fermented sorghum added. On the other hand, the groups with the additions of distilled fermented sorghum (Ef, Ff, Gf and Hf) did not change the acidity as compared with the control group. It was considered that the undistilled fermented sorghum had more active lactic acid bacteria than the distilled batch, which was exposed to high temperature. The total sugar contents were lower in the test groups with the additions of fermented sorghum or distilled fermented sorghum than that of the control group (26%). The reducing sugar contents were quite low in all groups, ranged from

Table 1. Composition of sorghum with different ratios of fermented sorghum or distilled fermented sorghum

Code Material added and added ratio (%)

Item

Water (%) Acidity1 Total sugar (%) Reducing sugar (%) Alcohol (%)

Ai 5% fermented sorghum addition 47.4 ± 1.3 2.8 ± 0.1** 36.2 ± 0.3 0.11 ± 0.01 0.26 ± 0.03

Bi 10% fermented sorghum addition 48.4 ± 1.1 3.9 ± 0.1** 35.1 ± 0.6* 0.12 ± 0.02 0.52 ± 0.07

Ci 15% fermented sorghum addition 49.4 ± 0.9 4.9 ± 0.1** 33.8 ± 0.4** 0.12 ± 0.02 0.80 ± 0.11

Di 20% fermented sorghum addition 50.4 ± 0.7* 5.9 ± 0.1** 32.7 ± 0.2** 0.13 ± 0.03 1.04 ± 0.12

Ei 5% distilled fermented sorghum addition 47.7 ± 1.2 2.6 ± 0.1** 36.4 ± 0.7 0.11 ± 0.01 < 0.20

Fi 10% distilled fermented sorghum addition 48.9 ± 1.0 3.7 ± 0.1** 34.9 ± 0.6* 0.11 ± 0.02 < 0.20

Gi 15% distilled fermented sorghum addition 49.9 ± 0.8 4.6 ± 0.0** 33.8 ± 0.3** 0.12 ± 0.02 < 0.20

Hi 20% distilled fermented sorghum addition 51.1 ± 0.6* 5.5 ± 0.1** 32.4 ± 0.2** 0.12 ± 0.02 < 0.20

Ii Control group2 47.5 ± 1.5 1.9 ± 0.1 37.7 ± 0.9 0.11 ± 0.01 < 0.201. Volume (mL) of 0.1 N NaOH required for neutralizing the acids of a 10-g sample.2. Newly cooked sorghum only.3. Data shown are representative of 3 replication and expressed as mean ± SD; * p < 0.05, ** p < 0.01 versus Control group.

Table 2. Composition of fermented sorghum before distillation

Code Fermented sorghum

Item

Water (%) Acidity1 Total sugar (%) Reducing sugar (%) Alcohol (%)

Af 5% fermented sorghum addition 56.3 ± 1.9 22.4 ± 1.6* 25.6 ± 0.7 0.7 ± 0.1 7.0 ± 0.2

Bf 10% fermented sorghum addition 56.5 ± 1.8 27.0 ± 0.8** 25.3 ± 0.7 0.7 ± 0.4 7.0 ± 0.1

Cf 15% fermented sorghum addition 58.2 ± 0.1 30.0 ± 0.9** 22.0 ± 1.3* 0.7 ± 0.4 7.1 ± 0.3

Df 20% fermented sorghum addition 56.8 ± 1.0 30.8 ± 0.5** 23.6 ± 2.2* 0.8 ± 0.6 6.3 ± 0.1

Ef 5% distilled fermented sorghum addition 57.1 ± 0.7 18.0 ± 0.5 25.4 ± 0.4 0.6 ± 0.1 7.2 ± 0.2

Ff 10% distilled fermented sorghum addition 57.2 ± 1.0 16.9 ± 0.3* 25.2 ± 0.8 0.4 ± 0.1 7.3 ± 0.1

Gf 15% distilled fermented sorghum addition 58.3 ± 0.5 17.2 ± 0.9 24.0 ± 0.4* 0.4 ± 0.1 7.5 ± 0.3*

Hf 20% distilled fermented sorghum addition 59.1 ± 0.2 17.2 ± 0.3 23.6 ± 0.4* 0.6 ± 0.2 7.4 ± 0.5

If Control group2 55.1 ± 2.1 18.2 ± 0.5 26.1 ± 0.8 1.0 ± 0.4 6.7 ± 0.31. Volume (mL) of 0.1 N NaOH required for neutralizing the acids of a 10-g sample.2. Newly cooked sorghum only. 3. Data shown are representative of 3 replication and expressed as mean ± SD; * p < 0.05, ** p < 0.01 versus Control group.


543

0.4 to 1.0%. In terms of alcohol content, groups with lower fermented sorghum quantities, Af (5%), Bf (10%) and Cf (15%), showed higher alcohol content than that of the control group If. On the other hand, Df (20%) with higher amount of fermented sorghum had lower alcohol concentration than the control group, though the difference was not significant. As for the groups with distilled fermented sorghum, they had higher alcohol content of about 7.5% as compared to 6.7% for the control group.

III. Content Analysis and Taste Test of Sorghum Spirits

As shown in Table 3, regardless of the addition of distilled fermented sorghum or fermented sorghum, the alcohol contents of all final products were controlled to around 61.5% ± 1%. However, in terms of total acid, there was no significant difference among all groups. The total acid ranged from 0.1% to 0.08%. As compared with the data in Table 2, groups Af, Bf, Cf and Df had higher acidity than the final product, sorghum spirits. We concluded that the acid contained in the cooked sorghum was mostly non-vola-tile lactic acid. Volatile acids (such as acetic acid) were not produced in significant quantities during the solid fermenta-tion. In terms of total ester (expressed as ethyl acetate) both the distilled fermented sorghum and fermented sorghum groups, had higher ester concentrations (0.37 - 0.42%) than the control group.

Taste tests showed that the spirits with 5% fermented sorghum and 5 - 20% of distilled fermented sorghum had stronger fragrances and better tastes. In addition, they received higher ratings than the spirits of the control group. On the other hand, the experimental groups with 10%, 15% and 20% fermented sorghum were not rated as high as the control group. These results indicated that the addition of 5% fermented sorghum, when preparing sorghum spirits, produced good results. The addition of 5 - 20% distilled fermented sorghum produced results superior to those of the control group. We also found that the addition of 15 - 20% distilled fermented sorghum yielded the best results.

IV. Comparison of the Fragrant Content in Sorghum Spirits

According to Table 4, the two major contributors to fragrance in the sorghum spirits were ethyl acetate and ethyl lactate. Other sources of fragrance included acetaldehyde, iso-butyraldehyde, 2-butanol, n-propanol, iso-butanol, n-butanol, 2-methyl-1-butanol, 3-methyl-1-butanol, ethyl succinate and 2-phenyl ethanol. In the sorghum spirits produced with the addition of fermented sorghum, the concentration of ethyl lactate was higher than that of the control group. In Fenjiu (a kind of Chinese spirits), different ratios of “optimal” ethyl acetate and lactate were suggested for different alcohols. For example, in Fenjiu, the full aroma and the unique taste to ethyl lactate can be fully experienced only if the ratio of ethyl acetate to ethyl lactate is 55 : 45. A lack of ethyl lactate caused the spirits to lose their complete flavor, while an excess causes the taste of ethyl acetate to Tabl

e 3.

Gen

eral

com

posi

tion

and

flav

or s

ensa

tion

of s

orgh

um s

pirit

s pr

epar

ed in

this

stu

dy

Cod

eFe

rmen

ted

sorg

hum

Item

Alc

ohol

(%)

Tota

l aci

d (%

)1To

tal e

ster

s (%

)2Fl

avor

des

crip

tion

Rat

ing

Af

5% fe

rmen

ted

sorg

hum

add

ition

62.0

± 0

.6 0

.09

± 0

0.38

± 0

.01*

Stro

nger

odo

r, be

tter t

aste

, bet

ter f

ragr

ance

82.6

Bf

10%

ferm

ente

d so

rghu

m a

dditi

on62

.7 ±

1.4

0.0

8 ±

00.

42 ±

0.0

2**

Stro

nger

odo

r, be

tter t

aste

, wor

se fr

agra

nce

76.3

Cf

15%

ferm

ente

d so

rghu

m a

dditi

on62

.0 ±

1.8

0.0

8 ±

00.

41 ±

0.0

1**

Stro

nger

odo

r, go

od ta

ste,

wor

se fr

agra

nce

75.5

Df

20%

ferm

ente

d so

rghu

m a

dditi

on61

.5 ±

0.6

0.0

9 ±

00.

42 ±

0.0

2**

Stro

nger

odo

r, ba

d ta

ste,

wor

se fr

agra

nce

73.8

E f5%

dis

tille

d fe

rmen

ted

sorg

hum

add

ition

62.3

± 0

.80.

08 ±

00.

39 ±

0.0

1**

Stro

nger

odo

r, be

tter t

aste

, bet

ter f

ragr

ance

82.9

F f10

% d

istil

led

ferm

ente

d so

rghu

m a

dditi

on62

.4 ±

1.1

0.09

± 0

.01

0.39

± 0

.01*

*St

rong

er o

dor,

bette

r tas

te, b

ette

r fra

gran

ce82

.1

Gf

15%

dis

tille

d fe

rmen

ted

sorg

hum

add

ition

61.6

± 0

.8 0

.08

± 0

0.37

± 0

.02*

Stro

nger

odo

r, be

tter t

aste

, bet

ter f

ragr

ance

84.5

Hf

20%

dis

tille

d fe

rmen

ted

sorg

hum

add

ition

62.3

± 0

.70.

08 ±

0.0

10.

38 ±

0.0

2*St

rong

er o

dor,

bette

r tas

te, b

ette

r fra

gran

ce85

.3

I fC

ontro

l gro

up3

61.9

± 1

.10.

1 ±

0.01

0.32

± 0

Stro

ng o

dor,

good

tast

e, w

orse

frag

ranc

e80

.21.

Tot

al a

cid

expr

esse

d as

ace

tic a

cid.

2. T

otal

est

er e

xpre

ssed

as

ethy

l ace

tate

.3.

New

ly c

ooke

d so

rghu

m o

nly.

4.

Dat

a sh

own

are

repr

esen

tativ

e of

3 re

plic

atio

n an

d ex

pres

sed

as m

ean

± SD

; * p

< 0

.05,

**

p <

0.01

ver

sus

Con

trol g

roup

.


544

Tabl

e 4.

Com

paris

on o

f the

con

cent

ratio

n of

vol

atile

com

poun

ds in

sor

ghum

spi

rits

prep

ared

in th

is s

tudy

Ferm

ente

d so

rghu

m a

dded

Dis

tille

d fe

rmen

ted

sorg

hum

add

ed

Con

tent

(ppm

)A

s (5%

)B

s(10%

)C

s(15%

)D

s(20%

)E s

(5%

)F s

(10%

)G

s(15%

)H

s(20%

)I s1

acet

alde

hyde

621

± 37

**61

0 ±

25**

776

± 41

**33

9 ±

20**

331

± 21

**42

1 ±

26**

565

± 30

**46

8 ±

25**

1737

± 6

0

i-but

yral

dehy

de75

± 4

**19

± 2

*19

± 2

*24

± 3

26 ±

222

± 3

20 ±

229

± 2

29 ±

2

ethy

l ace

tate

2425

± 5

9*18

42 ±

35*

*15

39 ±

32*

*19

07 ±

21*

*26

32 ±

25

2589

± 3

3*26

66 ±

22

2788

± 4

227

14 ±

32

met

hano

l23

7 ±

15**

130

± 10

**11

7 ±

7**

139

± 12

**15

4 ±

13**

126

± 11

**12

1 ±

10**

134

± 12

**18

3 ±

15

2-bu

tano

l16

± 1

**24

± 2

**29

± 2

**11

2 ±

6**

20 ±

1**

24 ±

2**

22 ±

1**

35 ±

2**

7 ±

1

n-pr

opan

ol22

8 ±

16**

286

± 19

**27

4 ±

11**

385

± 17

**25

8 ±

10**

254

± 9*

*26

7 ±

18**

275

± 18

**13

7 ±

6

i-but

anol

232

± 15

**26

8 ±

18**

252

± 9*

*23

5 ±

13**

216

± 11

**25

9 ±

16**

241

± 12

**29

0 ±

21**

182

± 7

n-bu

tano

l5

± 1

6 ±

15

± 1

4 ±

05

± 1

6 ±

15

± 1

6 ±

19

± 1

2-m

ethy

l-1-b

utan

ol

67 ±

4**

75 ±

4**

70 ±

3**

62 ±

3**

54 ±

3**

66 ±

2**

66 ±

5**

73 ±

4**

33 ±

2

3- m

ethy

l-1-b

utan

ol52

4 ±

25**

667

± 30

**64

5 ±

31**

564

± 37

**51

2 ±

23**

565

± 29

**67

8 ±

33**

635

± 29

**31

1 ±

15

high

er a

lcoh

ol10

7213

2612

7513

6210

6511

7412

7913

1467

9

acet

oin

10 ±

18

± 1

16 ±

37

± 1

12 ±

110

± 1

16 ±

218

± 1

29 ±

3

ethy

l lac

tate

1668

± 4

1**

3576

± 5

9**

3392

± 3

9**

2941

± 2

5**

1214

± 2

6**

1353

± 1

9**

1400

± 2

2**

1587

± 2

7**

515

± 34

furf

ural

304

± 20

*14

4 ±

15**

164

± 11

**25

2 ±

11**

256

± 13

**21

4 ±

17**

170

± 13

**19

6 ±

14**

376

± 22

acet

ic a

cid

526

± 27

415

± 30

**45

7 ±

27*

550

± 40

522

± 39

498

± 35

502

± 26

472

± 35

*53

7 ±

38

prop

anic

aci

d58

± 3

**59

± 2

**57

± 4

**55

± 3

**50

± 1

**48

± 3

**54

± 3

**53

± 4

**28

± 2

ethy

l suc

cina

te35

± 1

**31

± 1

**26

± 2

**35

± 2

**36

± 2

**31

± 1

**34

± 3

*29

± 2

**47

± 3

2-ph

enyl

eth

anol

6 ±

16

± 1

6 ±

17

± 1*

6 ±

16

± 1

7 ±

17

± 1*

4 ±

0

ethy

l pal

mita

te26

± 2

*24

± 2

**32

± 3

33 ±

228

± 2

27 ±

230

± 1

32 ±

230

± 2

ethy

l ole

ate

17 ±

1*

3 ±

1**

19 ±

118

± 1

16 ±

1*

17 ±

217

± 1

*18

± 1

19 ±

1

ethy

l lin

olea

te20

± 1

17 ±

124

± 2

26 ±

2*

21 ±

122

± 1

25 ±

1*

24 ±

1*

20 ±

1

Tota

l71

0082

1079

1976

9563

6965

5869

0671

6969

471.

Con

trol g

roup

: New

ly c

ooke

d so

rghu

m o

nly.

2. D

ata

show

n ar

e re

pres

enta

tive

of 3

repl

icat

ion

and

expr

esse

d as

mea

n ±

SD; *

p <

0.0

5, *

* p

< 0.

01 v

ersu

s C

ontro

l gro

up.


545

be overshadowed.(47) In this experiment, group As with 5% fermented sorghum had ethyl acetate and ethyl lactate in the ratio of 59 : 41. As compared to the control group, which had ethyl acetate and ethyl lactate in the ratio of 84 : 16, the experimental group was more similar to that of Fenjiu. On the other hand, experimental groups with 10% or more fermented sorghum contained more ethyl lactate than ethyl acetate. The ratios of ethyl acetate to ethyl lactate in these experimental groups were smaller than that in Fenjiu, causing a decrease in fragrance and an imbalance in taste. Other components that improved fragrance in sorghum spirits were n-propanol, 2-butanol, iso-butanol, n-butanol, 2-methyl-1-butanol and 3-methyl-1-butanol(5,7,31) therefore, the quantity of these components could also be used as the criteria for these products. The higher alcohol content in groups with either fermented sorghum or distilled fermented sorghum were all higher than that of the control group by about 100% (1,065 - 1,362 ppm in the experimental groups and 679 ppm in the control group). This result indicated that the addition of fermented sorghum to the newly cooked sorghum for brewing sorghum spirits could increase the higher alcohol content as well as the fragrance of the sorghum spirits.

The major difference between Taiwan-made sorghum spirits and Kinmen-made sorghum spirits was the content of higher alcohol(34). The concentration of higher alcohol in Chinese Fenjiu was between 800 ppm and 1,400 ppm(47). High content of higher alcohols not only improved the fragrance but also increased the bitterness of the spirits. Conversely, insufficient content of higher alcohols led to the lack of fragrance. Experimental group As in which 5% fermented sorghum was added to the cooked sorghum, yielded a final product with 1,072 ppm of higher alcohols. Compared to the control group (679 ppm), the experimental group was more desirable. This experimental group also had a more desirable ethyl acetate : ethyl lactate ratio than the control group. The flavor test ratings showed that spirits with 5% fermented sorghum had stronger fragrance and better taste than those with 10, 15 or 20% fermented sorghum. Therefore, when adding fermented sorghum to materials for brewing sorghum spirits, 5% fermented sorghum was considered optimal since the addition of higher fermented sorghum led to over-reproduction of lactic acid bacteria and affected the balance of the sorghum spirit fragrance and taste. It was also worth of noting that when adding 5 - 20% distilled fermented sorghum to the newly cooked sorghum, the quantities of higher alcohols and ethyl lactate were similar. While the experimental groups with distilled fermented sorghum had much higher contents of higher alcohol and higher ratios of ethyl acetate to ethyl lactate. This result also indicated that regardless of the quantities of distilled fermented sorghum (up to 20%) added, the fragrance and taste were all greatly improved. Due to lack of significant amounts of lactic acid bacteria, more distilled fermented sorghum can be used than fermented sorghum. However, considering the triple fermen-tation processes and the required equipments, the addtion ratio of distilled fermented sorghum to the raw materials should not exceed 20%.

ACKNoWLEDGMENTs

The authors are grateful to the Taiwan Tobacco and Liquor Corporation-Chiayi Distillery for providing the liquor and brewery equipment used in this study.

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