PRODUCTION OF GREEN TEA POWDER

19 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

Production of green tea powder was done through the spray drying process. There are some factors that can influence the drying process, such as inlet air temperature, outlet air temperature, blower speed, inlet and outlet humidity, and in feed condition, such as feed concentration, feed viscosity, feed temperature, and feed flow. This research used inlet temperature as the parameter. Inlet temperatures that have been used were 180 o C, 200 o C, and 220 o C. According to Kim et al. 2009, heat sensitive product can be dried within the recommended temperature of 180 – 220 o C inlet temperature. The outlet temperature was controlled at 80 o C and the blower speed was adjusted in 2500 rpm. To control the outlet temperature, feed rate was need to be adjusted. Green tea powder resulted from this process was then analyzed to observe physicalproperties, chemical composition, and volatile compound. The result is shown in Table 4.5. Figure 4. 7. Spray drying process 20 Figure 4. 8.Green tea powder

1. Physical properties

Table 4. 4.Physical propertiesof green tea powder Total solid Inlet temp. C Aw L a b Solubility Higroscopi city Bulk Density gmL 3 180 0.2602 ± 0.0010 d 58.38 ± 0.05 b 4.00 ± 0.11 c 18.62 ± 0.13 a,b 98.65 ± 0.77 b,c,d 8.51 ± 0.13 a,b 0.6043 ± 0.0077 f 3 200 0.2068 ± 0.0110 b 64.11 ± 0.07 d 3.98 ± 0.04 b,c 19.45 ± 0.04 e,f 99.21 ± 0.57 c,d 10.10 ± 0.15 c,d 0.5433 ± 0.0181 d,e 3 220 0.2158 ± 0.0010 b 57.80 ± 0.19 a,b 4.10 ± 0.11 c,d 18.40 ± 0.06 a 97.22 ± 1.69 a,b 12.56 ± 0.53 e 0.5865 ± 0.1269 f 6 180 0.2075 ± 0.0163 b 57.92 ± 0.25 a,b 3.80 ± 0.35 a 18.87 ± 0.14 b,c,d 98.79 ± 0.53 b,c,d 9.09 ± 0.94 b,c 0.5143 ± 0.1766 c 6 200 0.2584 ± 0.1396 d 56.48 ± 0.33 a 4.10 ± 0.03 c,d 18.46 ± 0.02 a,b 96.51 ± 1.08 a 11.16 ± 1.08 d,e 0.5596 ± 0.0002 e 6 220 0.2285 ± 0.0092 b,c 58.76 ± 0.89 b 3.98 ± 0.03 b,c 19.11 ± 0.33 d,e 97.57 ± 0.02 a,b,c 7.24 ± 0.97 a 0.5320 ± 0.0050 c,d 9 180 0.1796 ± 0.0058 a 59.42 ± 1.75 b,c 3.82 ± 0.07 a,b 18.96 ± 0.37 c,d 99.54 ± 0.29 d 11.36 ± 0.56 d,e 0.5467 ± 0.1361 d,e 9 200 0.2158 ± 0.0166 b 60.71 ± 0.26 c 4.01 ± 0.10 c 19.56 ± 0.08 f 97.15 ± 0.26 a,b 12.31 ± 1.47 e 0.4752 ± 0.0038 b 9 220 0.2438 ± 0.0267 c,d 63.69 ± 0.28 d 4.22 ± 0.01 d 20.39 ± 0.63 g 95.77 ± 0.47 a 12.33 ± 0.58 e 0.4272 ± 0.0024 a Value in a column followed by different letters are significantly p0.05 different

1.1. Water activity

Water activity Aw is an important index for spray-dried powder because it can greatly affect the shelf life of the powder. It is defined as the ratio of vapor pressure of water in a food system to vapour pressure of pure 21 water at the same temperature Fennema OR 1996.Water activity is different from moisture content as it measures the availability of free water in a food system that is responsible for any biochemical reactions, whereas the moisture content represents the water composition in a food system. High water activity indicates more free water available for biochemical reactions and hence, shorter shelf life. Generally, food with Aw 0.6 is considered as microbiologically stable and if there is any spoilage occurs, it is induced by chemical reactions rather than by micro-organism Bonazzi and Dumoullin 2011. The results shows water activity of green tea powder were in range of 0.18- 0.26. This means that the spray-dried powders were relatively stable microbiologically. However, the storage conditions also played an important role in this matter. Based on statistical analysis appendix 18, feed concentration did not significantly affect water activity, neither inlet temperature. However, interaction between total solid in feed and inlet temperature affected water activity of green tea powder resulting significant difference among the samples. The highest water activity is belong to green tea powder with 3 total solid in feed and 180 o C inlet temperature, the lowest water activity belong to green tea powder with 9 feed concentration and 180 o C inlet temperature, but it is not significantly different with other samples in the same subset.

1.2. Color

Color is one of the important sensory attributes of food and a major quality parameter in dehydrated food. During drying, color may change because of chemical or biochemical reaction. Enzymatic oxidation, Maillard reactions, caramelization, and ascorbic acid browning are some of the chemical reaction that can occur during drying and storage. Discoloration and browning during air drying may be result of various chemical reactions including pigment destruction Farias and Ratti, 2009. The attributes as indicator in determining color are L, a, b, and hue values. L value indicates the brightness of sample with range 0 black to 100 white. The a value indicates a micture colors of red and green. The +a value indicates red color with range 0-100, while –a value indicates green color with range 0--80. The b value indicates a combination of yellow and blue. +b range for 0-70 indicates yellowness while –b range for 0-- 70 for blueness. Based on Table 4.5., the result shows colors among samples are significantly different. The highest L value, which means the brightest color, belong to powder with 3 total solid in feed and 200 o C inlet temperature but it is not significantly different with powder 9 feed concentration and 220 o C inlet temperature. On the other hand, the darkest color, or the lowest L value belong to sample with 6 feed concentration and 200 o C inlet temperature, but it is not significantly different with other samples in the same subset. The highest a value belongs to sample with 9 feed concentration and 220 o C inlet temperature, which means this sample has the most reddish color. Sample with 22 6 feed concentration and 180 o C inlet temperature has the lowest a color which means this sample has the most greenish color. Powder that has the highest b color or the most yellowish is sample with 9 feed concentration and 220 o C inlet temperature, and the sample that has the lowest b value or the most bluish color is the one with 3 feed concentration and 180 o C inlet temperature. The result shows Figure 4.8. that green tea powder has greenish yellow color. Generally, increasing temperature increase L, a, and b value. High temperature makes shorter drying time, it caused browning reaction occurs faster. Besides, The Maillard reaction may occur in this research because green tea contains carbohydrate about 7 dry weight of tea leaf Chako et al, 2010. However, freeze concentration also gives the effect of reducing color in the feed preparation and it results in different color of origin.

1.3. Solubility

Solubility is the most reliable criterion to evaluate the behavior of powder in aqueous solution. This parameter is attained after the powder undergoes dissolution steps of sinkability, dispersability and wettability. Solubility describe feasibility of powder to be dissolved in water Chen and Patel, 2008. Based on Table 4.5., the result shows solubility of samples is in range of 95 – 99 , this result is agreement with Nadeem et. al. 2011 who reported solubility of spray dried mountain tea are mostly between 98.5 and 99.5 . The highest temperature belong to sample with 9 total solid in feed and 180 o C inlet temperature, the lowest solubility is belong to powder with 9 total solid in feed and 220 o C inlet temperature. Based on statistical analysis appendix 31., concentration did not significantly affect solubility, otherwise temperature did. Interaction between concentration and temperature significantly affect solubility of green tea powder. A hard surface layer might be formed over the powder particle at higher inlet temperature. This could prevent water molecules from diffusing through the particle. Consequently, decreased the wettability of the particle and reduced the solubility of the powder Chegeni and Ghobadian 2005.

1.4. Hygr oscopicity

Hygroscopicity is the ability of food powder to absorb moisture from high relative humidity environment. In the case of fruit powders, glucose and fructose are responsible for strong interaction with the water molecule due to the polar terminals present in these molecules Slade and Levine 1991. The results shows the highest hygroscopicity belong to sample with 3 feed concentration and 220 o C inlet temperature, but it is not significantly different with other samples in the same subset. The lowest hygroscopicity belong to green tea powder with 6 feed concentration and 180 o C inlet temperature, but it is not significantly different with other samples in the same 23 subset. Hygroscopicity of sample is varying among samples in range of 7.24 – 12.56. This is higher than reported by Jaya and Das 2004, higroscopicity in instant coffe powder which is in range 9.09–10.32 . But the result is lower than higroscopicity of spray dried mango powder which has higroscopicity 16.5 . This variation can be explained by difference of material and condition of drying process. High higroscopicity indicates its strong capacity to attract water molecules when in contact with the surrounding air. This can lead to cacking and agglomeration in powder. Adding carrier, such us maltodextrin can help to lower higroscopicity Ahmed et al 2010; Rodríguez-Hernández et al. 2005; Cai and Corke 2000.

1.5. Bulk density

Bulk density is one of food powder properties. The result shows bulk density is significantly different among samples in range 0.4272 ± 0.0024- 0.6043 ± 0.0077gmL. The highest bulk density belong to sample with 3 feed concentration and 180 o C inlet temperature, and the lowest bulk density belong to sample with 9 feed concentration and 220 o C inlet temperature, but both of them are not significantly different with other samples in the same subset. Higher total solid in feed decreased the bulk density, as well as higher temperaturedecreased the bulk density. This result is in agreement with Goula and Adamopoulos 2010, increased inlet air temperature causes a reduction in bulk density, as evaporation rates are faster and products dry to a more porous or fragmented structure. Walton 2000 reported that increasing the drying air temperature generally produces a decrease in bulk and particle density, and there is a greater tendency for the particles to be hollow. Also, the higher moisture content of powder, the more particles tend to stick together, leaving more interspace between them and consequently resulting a larger bulk volume Goula and Adamopoulos 2005.

2. Chemical compound

Table 4. 5The result of chemical analysis of green tea powder Total solid Inlet temp. o C Moisture content wb Total polyphenol db Gallic acid db Teaine db Catechin db 3 180 4.35 ± 0.02 c 31.22 ± 0.11 h 2.21 ± 0.10 a 6.50 ± 0.02 c 16.53 ± 0.28 b 3 200 4.41 ± 0.02 c 30.22 ± 0.15 g 2.38 ± 0.01 b,c 6.33 ± 0.06 b 15.17 ± 0.02 a 3 220 4.31 ± 0.04 c 27.86 ± 0.04 f 2.72 ± 0.01 d 7.38 ± 0.02 f 21.79 ± 0.07 c 6 180 4.17 ± 0.02 a 26.42 ± 0.07 e 2.38 ± 0.00 b,c 7.06 ± 0.01 d 26.16 ± 0.13 f 6 200 4.16 ± 0.11 a 23.82 ± 0.20 d 2.46 ± 0.07 c 6.47 ± 0.02 c 16.18 ± 0.31 b 6 220 4.04 ± 0.01 a 23.96 ± 0.27 d 2.31 ± 0.14 a,b 6.20 ± 0.01 a 23.77 ± 0.07 d 9 180 4.29 ± 0.01 b 22.40 ± 0.10 c 2.62 ± 0.01 d 7.41 ± 0.00 f 24.75 ± 0.15 e 9 200 4.06 ± 0.03 a 21.07 ± 0.07 b 2.68 ± 0.07 d 7.06 ± 0.06 d 24.47 ± 0.14 e 9 220 4.10 ± 0.00 a 20.65 ± 0.01 a 2.66 ± 0.04 d 7.26 ± 0.00 e 26.20 ± 0.04 f Value in a column followed by different letters are significantly p0.05 different 24

2.1. Moistur e content

Moisture content describes water composition in food. The result shows moisture content of green tea powder varies in range of 4.06 – 4.41 , a small variation means that the drying process was done uniformly for all samples. Statistical analysis shows higher temperature lower the moisture content. This result is in agreement with Quek et al. 2006 who reported the moisture content of the spray-dried powders decreased with the increased in inlet and outlet air temperature. This is because at higher inlet temperature, the rate of heat transfer to the particle is greater, providing greater driving force for moisture evaporation. Consequently, powders with reduced moisture content are formed.

2.2. Total polyphenol content

Total polyphenol content was analyzed using gallic as standard. The result Table 4.6. shows vary amount of total polyphenol content in sample in range 20.65 – 3122 . This result is higher than total polyphenol content in instant tea reported by Sinija et al. 2007. The highest amount of total polyphenol is found at green tea powder with 3 feed concentration and 180 o C inlet temperature, and the lowest one is found at sample with 9 feed concentration and 220 o C inlet temperature, but both of them are not significantly different with other samples in the same subset. Increasing total solid results decreased polyphenol content. Increasing inlet temperature also results decreased polyphenol content. This can be occurred because higher feed concentration means longer time in freeze concentration process in which can release polyphenol content during process, higher temperature caused degradation of polyphenol. Georgetti et al. 2008 also reported a slight decrease in the total polyphenol content of the spray-dried soybean extract by increasing the inlet air temperature. Monica et al. 2009 reported that increased temperature caused degradation on polyphenol content in apricot, especially epicatechin and quercetin.

2.3. Gallic acid

Gallic acid was analyzed using HPLC. Based on Table 4.6., the result shows vary amount among sample. Gallic acid of green tea powder is in range of 2.21 – 2.26 db. The highest gallic acid content is found at sample with 3 total solid temperature and 220 o C inlet temperature but it is not significantly different with other samples in the same subset. Yet the lowest gallic acid content is found at sample with 3 total solid in feed and 180 o C inlet temperature. Generally, higher total solid and higher temperature result higher gallic content. It can be explained by high total solid in feed and short time drying process. 25

2.4. Teaine

Teaine is one of the components that affect flavor of green tea. Based on Table 4.6., teaine content in sample varies among samples in range 6.20 – 7.41 . This result is higher than teaine content in instant tea as reported by Shinja et al. 2007. The highest teaine content is found at sample with 3 feed concentration and 220 o Cinlet temperature, and the lowest is found at the sample with 6 feed concentration and 220 o C inlet temperature but not significantly different with other samples in the same subset. Interaction between feed concentration and inlet temperature significantly affectedteaine content.

2.5. Catechin

Catechin is the important group of tea leaf compound that affects tea flavor. Catechin was analyzed using HPLC. Based on Table 4.6., catechin content of green tea powder varies among samples in range of 15.17 – 26.20 . The highest catechin content is found at the sample with 9 feed concentration and 220 o C inlet temperature, And the lowest catechin content is found at the sample with 3 feed concentration and 200 o C inlet temperature but it is not significantly different with other samples in the same subset. Increasing feed concentration results increased catechin.The highest catechin amount was found in sample with 9 feed concentration 220 o C inlet temperature and 6 feed concentration and 180 o C inlet temperatuure. It can be explained by high total solid content in feed and short drying time.

3. Volatile compound

Figure 4. 9.Volatile compounds in green tea powder Volatile compound analysis was done by GC-MS equipment and the extraction was done by SPME. There are seven major groups of volatile compounds found in green 50000 100000 150000 200000 250000 300000 3 180 3 200 3 220 6 180 6 200 6 220 9 180 9 200 9 220 P e a k a re a g ra m Treatment Green tea powder Alcohol Ket one Hidrocarbon Acid Aldehide Azole Terpene 26 tea extract, alcohol, ketone, hydrocarbon, acid, aldehide, azole, and terpene. The amount of those compounds varies among samples. Green tea powder with 6 feed concentration and 200 C inlet temperature contains all group of volatile compound except aldehide. It can be noticed that green tea powder with feed concentration 3 and 9 contain limited number of volatile compound group. It can be occurred because low level of total solid and long time freeze concentration process that can reduce volatile compound amount and type. Alcohol, ketone, hydrocarbon, acid, aldehide, azole, and terpene are major group of volatile compound that commonly found in green tea. The previous studies by Pripdeevech and Machan 2011 also found these compounds in tea, Zhong et al. 2012 also found these compounds in pu-erh tea Chinese tea. Alcohol group of tea consist of linaool, phenylethyl alcohol, terpineol, nerol, geraniol, and others. The biggest alcohol constituent found in green tea powder is butadienol, the biggest ketone constituent found in green tea powder is butanone, the biggest hydrocarbon constituent found in green tea powder is dodecane, the biggest acid constituent found in green tea powder is acetic acid, the biggest aldehide constituent found in green tea powder is hexanal, the biggest azole constituent found in green tea powder is benzothiadiazole, and the biggest terpene constituent found in green tea powder is azulene. Volatile compound composition in green tea powder is different with volatile compound composition in green tea leaf. It means there were some reactions occurred during the process. These reaction causes some change in volatile compounds composition.

D. EFFECT OF TEMPERATURE AND FEED CONCENTRATION