The Analysis And Reasonable Evaluation Methods Of Korea Green Tea

In this research, we selected 18 representative Korean green tea products, which are different in the producing area, the processing methods and producing time, to analyse their quality related main components. We also utilize different treatments, including the different tea pouring temperature, time and tea-water proportion treatment, to compare the chemical composition contents like tea polyphenol, amino acids and caffeine in green tea. Results show that the factors of temperature, time and the tea-water proportion could do effects both on the composition of tea soup and on the sensory tea quality. Furthermore, on the basis of Chinese founded tea quality judgment methods and biochemical analytical methods, we are trying to find out the principle and theories for quality judgments of Korean green tea.By analysis of tea samples from three different producing areas, we find that there is significant difference in the contents of tea polyphenols and amino acids. From the sensory evaluation of samples by different processing methods, results show that all the mechanically produced fired green tea run up a score obviously higher than the fired green tea handmade, which imply that nowadays the hand-make producing is limited in Korea, while mechanical production of fired green tea has reached a relatively more high lever. By detecting of different tenderness of tea samples, we find that the regular changed tendencies for the contents of tea polyphenols, amino acids, caffeine and total extracts are unanimous, that is, all these contents are low in the tender leaves and increase as the growth of maturity, but then decrease in the hard mulberry leaves.The Water temperature for tea soup is important in effecting the concentration of tea extracts, concluding tea polyphenol, amino acids, caffeine and total extracts. Itshows that all the amounts of tea extract increase as well as the water temperature goes up. After treated with different temperature, we analyze the tea polyphenol, amino acids and caffeine in tea soup, and find that the final concentrations of tea polyphenol and caffeine increase with prolonged pouring time. It's also increased for the amino acids, but such a trend would slow down with prolonged pouring time. From the current research, both the water temperature and pouring time could affect the tea quality significantly.The tea-water proportion could also affect the concentrations of tea polyphenols, amino acids, caffeine and total extracts in tea soup. It shows that their concentration decrease gradually with increased water capacity, respectively, and it reaches a peak for extracts concentration when using 100 ml water. Meanwhile, the tenderness has relative effects on the quality of green tea soup. It shows that along with the maturation of green tea, the concentration of all components in the soup reduced, and there is a significant relationship between the tenderness and green tea quality.Green teas with different processing methods, which are treated with different water temperature and pouring time, could affect the components in tea soup significantly. With the water temperature goes up, the tea polyphenols, amino acids, caffeine and total extracts increase accordingly. With the pouring time prolonged, those components increased more significantly in the tea soup. Under both the treatment of different temperature and time, there is significant relationship among green teas from different producing area in Korea.When the samples are poured by using 100°C hot water for 4 min, we analyze five different tea-water proportion treatments to search their highest appraisements. Results show that the aroma is best with the ratio of 3:200, the soup color is best with the ratioof 3:250, and the taste is best also with the ratio of 3:200. When the samples are poured by using 100°C hot water for 5 min, the concentrations of tea polyphenols, amino acids and caffeine are the highest and the C/N is the least at the ratio of 3:100 in all the treatments.We conclude from the comparison of different methods as that: There is not obvious difference in the accuracy rates for the sensory evaluation of experienced evaluators, but a discrepancy for that of unexperienced evaluators. Nevertheless, the method for green tea appraising by prepared with 100°C hot water for 4 min at the ratio of 3g: 200ml is obviously better than that prepared with 100°C hot water for 5 min at the ratio of 3g: 150ml.In conclusion, we bring forward a relatively reasonable appraising method for Korean green tea, that is, using 3 grams dry Korean green tea to prepare with 200 ml 100°C hot water for 4 min.