Degradation of Green Tea Catechins in Tea Drinks Assignment

Degradation of Green Tea Catechins in Tea Drinks - Assignment Example This study is significant because it studies the effect of processing conditions on GTC content. It is important to conserve the GTC content of tea during processing to retain its beneficial effects. Results of the study reveal that the GTC content of processed tea is significantly low compared to traditionally prepared tea. While a cup of traditionally brewed tea contains 400-500 mg of GTC, processed tea contains only 3-60 mg GTC. GTC is stable at room temperature. About 10-15%, GTC is lost when tea is heated up to 98 ?C for 15-30 minutes, with additional 5% loss on prolonged heating. Autoclaving at 120 ?C for 20 minutes, which is yet another step during processing, leads to a loss of 23% GTC. This loss is directly proportional to the pH of the medium. Furthermore, about 80% of the GTC content is degraded in a buffer medium of pH 6. The stability and shelf life of GTC is also found to be dependent on pH content in the absence of other ingredients. Half of the GTC content is lost wit hin 3 months at a pH below 4.5. Sucrose has no effect on the stability of GTC while citric acid leads to a faster degradation. Ascorbic acid has a protective effect in the first month after which it accelerates the degradation. In addition, the results also reveal that at high temperatures, EGCG undergoes epimerization to form GCG. This explains the contrasting GCG content between traditionally prepared tea and processed tea, wherein, the GCG content is higher by 45% in processed tea. Overall, it can be concluded that GTC degrades easily at high temperature and pH, and that the stability of GTC depends on the presence of other ingredients. Further studies that focus on the effect of each ingredient present in processed tea on the stability and speed of degradation of GTC are required. II. Coffee and Green Tea as a Large Source of Antioxidant Polyphenols in the Japanese Population (Fukushima et al 1253-1259) The objective of this study was to evaluate the total consumption of polyphe nols by Japanese people. Polyphenols are well known for their antioxidant activity and beverages are a major source of polyphenols in Japan. The findings of this study suggest that an individual per day consumes an average of 853 mg of polyphenols. The largest source of polyphenols in the Japanese population is coffee, which provides 200 ml of polyphenols in every 100 mL. The average polyphenol consumption through coffee is found to be 426 mg/day. The second largest source of polyphenol is Green tea, which contributes up to 292 mg polyphenols/day. Thus, coffee and green teas constitute up to 70% of the total beverage consumption and are the largest sources of polyphenols. Among fruits and vegetables, satsuma oranges and onions are the most consumed and provided 9 and 4 mg of polyphenols, respectively, per day. Cacao mass (chocolate) and black pepper contribute about 0.8 g and 0.2 g polyphenols per day. Measurement of the antioxidant activities correlates well with the total polyphen ol content of all the tested consumables, suggesting that the in vitro antioxidant activities are proportional to the total polyphenol quantities. Future studies will have to examine whether in vivo antioxidant properties of these polyphenols correlate well with those observed in vitro. III. Content of Potentially Anticarcinogenic Flavonoids of Tea Infusions, Wines, and Fruit Juices (Hertog, Hollman, and Putte 1242-1246) This study attempted to evaluate the concentrations of various anti-carcinogenic flavonoids in beverages such as tea, wines and fruit juices. The study found