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that generally, concentrations of linalool and hexanal seem to play an important role in the quality of green tea.
B. PRODUCTION OF CONCENTRATED GREEN TEA EXTRACT
Dried green tea leaf was extracted by dissolving in hot water 90
o
C and then was filtered using pressing machine as shown in Figure 4.2to obtain green tea extract.
Figure 4. 2.Pressing machine
Green tea extract from previous step was then concentrated using freeze concentrating machine as shown in Figure 4.3. The principle of this machine is resulting
slurry of ice crystals in a fluid concentrate. The ice crystals were then removed in some way, in this study it used centrifuge machine, as shown in Figure 4.4, for separating the
ice crystals and a concentrated product. The total solid in fluid concentrate will increase as longer of freeze concentration time. There are three determined total solid, 3, 6,
and 9. The main advantage of freeze concentration process is it does not use high temperature to increase concentration of extract. On the other hand, it has some
disadvantages, such us limited degree of final concentration achieved, long time process, and some compound can be disposed together with the ice crystal, as the suspended
material can be a nucleus on crystallization process.
The concentration of extract was measured using refractometer and was confirmed using oven method. Hand refractometer is an equipment to measure TDS that content in
fruit, food product that is contained fruit, and sucrose solution Nielsen, 1996. Nowadays, hand refractometer is used in process of made a solution in the industry, like
milk industry and beverage industry. The principle of hand refractrometer is measure the index of refraction from the food that contain of carbohydrate. The unit of refratometer is
˚Brix that equal with percentage of sucrose solution g sucrose 100 g sample. Because of this research used green tea extract as the sample, which it is non-sucrose sample, the
calibration of hand refractometer measurement with oven method must be done. The relationship between total solid measurement using refractometer and total solid
measurement using oven method is shown in Figure 4.5. The figure shows linear relationship between
o
brix and total solid that means refractometer can be used to measure concentration in green tea extract.
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Figure 4. 3. Freeze concentrating machine
Figure 4. 4.Centrifuge machine
Figure 4. 5.Relationship between
o
brix refractometer and concentration oven method
y = 0,73x + 1,333 R² = 0,980
1 2
3 4
5 6
7
2 4
6 8
Concentration
Brix
Relationship Betw een Brix and Total Solid
18
The chemical compositions and volatile compounds of concentrated green tea extract have been studied. The chemical composition is shown in table 4.4. and the
volatile compounds are shown in figure 4.6.
Table 4. 3.Chemical composition of green tea extract
Chemical composition Sample
3 6
9 Total polyphenol content mg100 mL
25.19 ± 0.06
a
33.54 ± 0.01
b
41.37 ± 0.05
c
Gallic acid µg mL 1.44 ± 0.02
a
2.45 ± 0.01
b
4.45 ± 0.02
c
Caffeine µg mL 5.09 ± 0.04
a
8.56 ± 0.04
b
14.37 ± 0.05
c
Total catechin µg mL GC µg mL
EGC µg mL C µg mL
EC µg mL EGCG µg mL
GCG µg mL ECG µg mL
12.02 ± 0.12
a
2.12 ± 0.01
a
4.64 ± 0.01
a
1.34 ± 0.03
a
1.22 ± 0.02
a
1.93 ± 0.02
a
0.50 ± 0.04
a
0.27 ± 0.01
a
26.74 ± 0.68
b
4.03 ± 0.01
b
9.38 ± 0.04
b
2.78 ± 0.00
b
2.51 ± 0.00
b
5.49 ± 0.00
b
1.52 ± 0.03
b
1.00 ± 0.07
b
47.95 ± 0.06
c
7.13 ± 0.01
c
16.35 ± 0.05
c
5.03 ± 0.01
c
4.50 ± 0.01
c
10.37 ± 0.01
c
2.83 ± 0.01
c
1.75 ± 0.00
c
Value in a column followed by different letters are significantly p0.05 different. Based on the Table 4.4., the result shows the highest amount of all the chemical
composition is found in extract green tea 9. This can be explained by extract 9 has the highest total solid of all samples. The highest catechin constituent in all samples is EGC
then followed by EGCG, GC, C, EC, GCG, and ECG. This is different from green tea Leafs composition in which EGCG is the highest catechin constituent. According to
Labbe et. al. 2008, EGCG extraction is more timetemperature dependent than EGC which means EGCG is more sensitive than ECG.
Figure 4. 6.Volatile compounds in green tea extract
There are three main groups of volatile compounds in green tea extract; alcohol, hydrocarbon, and terpene. Pripdeevech and Machan 2011 also found those compounds
10000 20000
30000 40000
50000 60000
Volatile compounds
Ext ract 3 Ext ract 6
Ext ract 9
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in green tea. The Extract 3 contains the highest amount of those compounds, followed by extract 6 and extract 9. Alcohol is the biggest constituent in extract 3 and 6,
but it was not found in extract 9. The biggest part of alcohol component is ethanol, the biggest part of hydrocarbon component is dichloromethane, and the biggest part of
terpene is azulene. This composition is different with green tea leaf which means there is reaction occurred during extraction and freeze concentration process that caused change
in volatile compound composition. Kim et al. 2007 also reported change in flavor of green tea liquor during heating caused by change in volatile compound composition.
C. PRODUCTION OF GREEN TEA POWDER
