TEA Effects of Inlet Temperature and Feed Concentration on Quality of Spray Dried Instant Green Tea Powder

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II. LITERATURE REVIEW

A. TEA

Tea is leaf of Camellia sinensis plant. The taxonomy of tea plant is shown in Table 2.1 and the figure of tea plant is shown in Figure 2.1. Figure 2. 1. Green tea plant Table 2. 1. Taxonomy of tea plant Common name Tea Kingdom Plantae Division Spermatophyta Subdivision Angiospermae Class Dicotyledone Ordo Guttiferales Family Theaceae Genus Camellia Species Camellia sinensis Tea Camellia sinensis is the most consumed drink in the world next to water and the amount of consumption well exceeds coffee, beer, wine, and soft drinks Rietveld 2003. The reasons for the worldwide popularity of tea are unique aroma and characteristic flavor.But recently, its popularity has increased due to its potential health benefits against cardiovascular diseases and cancer as well as pharmaceutical activities such as antihypertensive, antiateriosclerotic, hipocholesteroladmic, and hypolipidemic properties mostly from activities of antioxidant flavonoids present in tea Cheng 2006. Catechin is major polyphenol in green tea. Sutherland et al. 2005 reported some beneficial properties of catechin. Catechins chelate metal ions such as copperII and ironIII to form inactive complexes and prevent the generation of potentially damaging free radicals. Another mechanism by which the catechins exert their antioxidant effects is through the ultrarapid electron transfer from catechins to ROS-induced radical sites on DNA 4 Anderson et al. 2001. A third possible mechanism by which catechins scavenge free radicals is by forming stable semiquinone free radicals, thus, preventing the deaminating ability of free radicals Guo et al. 1996. In addition, after the oxidation of catechins, due to their reaction with free radicals, a dimerized product is formed, which has been shown to have increased superoxide scavenging and iron-chelating potential Yoshino et al. 1999 Epigallocatechin gallate has shown evidence of modulatinapoptotic pathways to protect against oxidative stress.Koh et al. 2003 showed that after hydrogen peroxideexposure in PC12 cells, EGCG inhibited many points ofthe apoptotic sequence, including caspase 3, cytochromec release, polyADP-ribose polymerase cleavage, theglycogen synthase kinase-3 pathway and modulated cellsignaling by activating the phosphatidyl inositol-3 kinasePI3KAkt pathway which promotes cell survival. Furtherstudies have confirmed this by showing that after 3-HKexposure in SH-SY5Y human neuroblastoma cells, apoptosisand caspase 3 activity were inhibited by EGCG Jeong et al. 2004. Catechins can also modulate apoptosis by altering the expression of antiapoptotic and proapoptotic genes. Epigallocatechin gallate prevented the expression of proapoptotic genes Bax, Bad and Mdm2 while inducing the antiapoptotic genes Bcl-2, Bcl-w and Bcl-xL to protect SH-SY5Y cells from 6-OHDA-induced apoptosis Leviteset al. 2002. Indonesia is one of the countries that produce tea. Tea production in Indonesia reached 150.342 tons in 2010 Ministry of Agriculture. Indonesia’s tea production rate is 1.516 kg per hectare in a year which is lower than other tea producer countries. The government has taken some actions to increase tea production rate. These include uses of superior variety and education to tea farmer Ministry of Agriculture. Other countries that produce tea are India, China, Sri Langka, Myanmar, also Thailand. Tea produced by these countries has each characteristic. Tea from the genus Camellia can be divided into three categories based on tea manufacturing fermentation process: green tea unfermented, oolong tea partially fermented, and black tea fully fermented. Green tea has been regarded as a rich source of catechin and its derivatives called tea catechins or flavan 3-ols including catechin C, epicatechin EC, epigallocatechin EGC, epicatechin gallate ECG, epigallocatechin gallate EGCG, and gallocatechin gallate GCG that contribute to antioxidant capacity and organoleptic properties Fernández et al. 2000. For green tea manufacturing, freshly plucked tea leaf is immediately steamed or pan-fired to inactivate polyphenol oxidase and native microflora that initiate and catalyses the aerobic oxidation of tea catechins during tea fermentation. Then it is allowed to whitering and drying process. Green tea is popular in the Southeast Asian countries. The origin of green tea is the southwestern plateau region of China and golden delta area located partially in China, Vietnam, and Myanmar Burma. Green teas differ depending on the type of process, whether it is steamed or pan-fired. Generally, green tea is steamed in Japan and pan-fired in the other Southeast Asian countries. Green tea has light yellowish green to green color when it is brewed. High-quality green tea has a slight greenish flavor given by certain terpenes such as linalool. Generally, concentrations of linalool and hexanal seem to play an important role in the quality of green teas Kato and Sibamoto 2001. Green tea contains some compounds like teaine, cathecin, and organic acid that affect flavor and aroma of green tea. Those compounds also bring beneficial health to the human. Teaine 1,3,7-trimetylxantine, C8H10N4O2 is a plant alkaloid, one of the few plant products which the general public is readily familiar because of its occurrence in beverages 5 such as coffee and tea, as well as various soft drinks. Teaine extract from tea is added to some pain-relief medicines. teaine compound is well known for its stimulant effect and is present at 2-4 of dried tea leaf weight, depending on the types and quality of teas Yoshida et al 1999. Studies using animal models show that green tea catechins provide some protection against degenerative diseases. Green tea catechins could also act as antitumorigenic agents Roomi et al, 2007 and as immune modulators in immunodysfunction caused by transplanted tumors or by carcinogen treatment. Green tea consumption has also been linked to the prevention of many types of cancer, including lung colon, esophagus, mouth, stomach, small intestine, kidney, pancreas, and mammary glands Koo and Cho 2004. This beneficial effect has been attributed to the presence of high amounts of polyphenols, which are potent antioxidants. In particular, green tea may lower blood pressure and thus reduce the risk of stroke and coronary heart disease. Some animal’s studies suggested that green tea might protect against the development of coronary heart disease by reducing blood glucose levels and body weight Tsuneki et al 2004.

B. SPRAY DRYING