25 3 solid concentration in feed
and inlet air temperature 180˚C has the lowest one. Based on ANOVA, significant differences were found among the samples.
According to Nadeem et al 2011 when the inlet air temperature increased, the L values decreased while the b values increased. This implied that the color of the powders became little
darker at higher drying temperatures. But, the result in this study is not same with literature, the L value of powder increased significantly as concentration of feed and inlet temperature increase,
except on concentration 3, the higher temperature will decrease the L value. The a and b value of powder increased significantly as concentration of feed increase and as inlet temperature
decrease. This implied that the different concentrations of feed and inlet temperatures on product resulted the varieted and different color significantly p0.05. The higher of inlet temperature
and feed concentration affect the time of drying. Contact of powder with inlet and outlet air temperature made browning reaction occurs faster. Besides, The Maillard reaction may occur in
this research because green tea contains carbohydrate about 7 dry weight of tea leaves Chako et al, 2010. However, freeze concentration also give the effect of reducing color in the feed
preparation and it resulted different color of origin.
1.3. Solubility of Green Tea Powder
Many factor affect the solubility, including processing conditions, storage condition, composition, pH, density, and particle size. It has been found that increasing product
temperatures is accompanied by increasing protein denaturation, which decreases solubility Okos, 1992. But, Goula and Adamopoulos 2005 reported that the more soluble powder at the
high drying temperatures. The solubility results on Table 7 show that inlet air temperature gave the various result of powder solubility but an increases of feed concentration until 9 can
increase percentage of solubility.
The solubility of green tea powder was found vary from 75.56-91.17. The best condition which has the highest percentage of solubility is 9 solid concentration in feed and
inlet temperature 220˚C and the lowest solubility was found in tea powder with treatment on 6 solid concentration in feed
and inlet air temperature 200 and 220˚C. The powder with treatment 9 solid concentration in feed and inlet air temperature has the highest percentage of solubility
because that condition has the lowest bulk density and time of drying. A low bulk density 0.4 gmLis required for good dispersibility of nonfat drymilk. It was found that particle
agglomeration, which increases particle size, increased sinkability. The larger particles were less soluble and the longer drying time was required to made the dry large particles Okos, 1992.
1.4. Hygroscopicity of Green Tea Powder
The result of percentage of hygroscopicity ia variated about between 8.84-17.84 . The highest percentage of hygroscopicity was found in the tea powder with treatment 3 solid
concentration in feed and inlet air temperature 180˚C and the lowest percentage of
hygroscopicity was found in the tea powder with treatment 3 solid concentration in feed and inlet air temperature 220˚C. According GEA Niro Research Laboratory, green tea powders in
this study have nonhygroscopic 10 to hygroscopic 15.1-20.0 characteristic. In this study, inlet temperature give affect on hygroscopicity but feed concentration not give the affect.
This observation is similar to that repored by other researchers, increases in inlet air temperature lead to hygroscopicity and as results to lower caking-degree Goula Adamopoulos, 2010.
26
2. Chemical Analysis Results
The chemical analysis results of green tea powder shown in Table 8. The chemical results were found variated and the significant differences were found among the samples of
each chemical analysis, except caffeine.
Table 8. The chemical analysis results of green tea powder Conc
Inlet Temp.
˚C Moisture
content db
Total Polyphenols
ww db Antioxidant
mmol Trolox100 g db
Catechin g100 g db
Caffeine g100 g db
3 180
3.33 ± 0.13
b
30.55 ± 0.85
a
226.38 ± 7.22
b.c
21.77 ± 0.45
a.b.c.d
5.37 ± 0.04
a
200 2.76 ± 0.25
c
27.44 ± 0.04
b
221.15 ± 6.33
c
21.14 ± 0.42
a.b.c.d
5.09 ± 0.25
a
220 3.77 ± 0.13
a
27.27 ± 0.04
b
218.80 ± 0.98
c
23.23 ± 2.28
a
5.64 ± 0.47
a
6 180
2.76 ± 0.02
c
30.69 ± 0.17
a
247.77 ± 5.65
a
20.69 ± 0.81
b.c.d
4.96 ± 0.52
a
200 2.67 ± 0.01
c
29.98 ± 1.02
a
235.62 ± 0.27
a.b.c
19.28 ± 1.49
d
5.02 ± 0.37
a
220 2.77 ± 0.06
c
29.89 ± 0.34
a
232.54 ± 4.20
a.b.c
20.43 ± 0.21
c.d
5.37 ± 0.16
a
9 180
3.11 ± 0.12
b
29.69 ± 0.22
a
241.67 ± 5.38
a.b
22.24 ± 0.09
a.b.c
5.16 ± 0.61
a
200 2.33 ± 0.15
d
30.34 ± 0.54
a
247.63 ± 5.10
a
22.97 ± 0.88
a.b
5.63 ± 0.24
a
220 3.22 ± 0.08
b
30.16 ± 1.12
a
243.63 ± 16.51
a.b
20.60 ± 0.05
b.c.d
5.37 ± 0.18
a
1Values are mean ± SD n=2 2Value in a column except caffeine followed by different letters are significantly p0.05 different.
2.1 Moisture content of Green Tea Powder
Moisture content expresses the amount of water present in a moist sample. Two bases are widely used to express moisture content, namely moisture content wet basis and moisture
content dry basis. Base on Table 8, powders moisture content varied from 2.33-3.77 wet basis. The highest moisture content was found in tea powder with treatment feed concentration 3 and
inlet air temperature 220˚C and the lowest polyphenol content was found in tea powder with treatment feed concentration 9 and inlet air temperature 200˚C. The dried product that
produced by spray dryer usually has moisture content below 5 Singh and Heldman, 2009. Powders moisture contents were found to be in the targeted range of 5 g100g as it is suggested
to be in the range of 3-5 g100g for instant tea powder to provide better stability during packaging and storage Sinija Mishra, 2008.
Base on the results, m oisture content was significantly influenced by inlet air temperature
and feed concentration. An increase in inlet air tem perature until 200˚C gave a decrease in
moisture content significanly. The increase inlet temp. until 220˚C gave an increase moisture
content. It cause by drying temperature difference between air inlet and air outlet. the higher the temperature difference. the lower ability to produce a unit weight of product of constant residual
moisture content from a constant solid feedstock Master, 1991. Besides. the moisture content of the spray-dried powders decreases with the increase in inlet and outlet air temperature Quek
et al, 2007; Tonon et al, 2008. An increase feed concentration will require more higher inlet temperature of spray drying. The sample contain 9 concentration and it is dried with inlet air
27 temperature 180˚C. the sample cannot dry properly and it stuck in the wall and result the higher
of moisture content.
2.2 Total Polyphenols Content
