The Optimization Of Metheds In The Organoleptic Evaluation Of Famous Green Tea

The quality of famous green tea is uneven and variable. Since the figuration and leaf shape are distinct, there is significant difference in various extracted tea components, which is really very complex. In this study, different shaped tea samples are selected representative for analysis of the factors referred to the extractablity of green tea, thus provided the consulting value as the chemical reference for optimizing the organoleptic evaluation of famous green tea.In this paper, the effects of tea shape, tea brewing temperature, and tea brewing duration on the extractability of chief taste components including total free amino acids, tea polyphenols and caffeine were investigated. Results showed that the concentration of taste components in tea liquor increased with the prolonged brewing duration and the raising brewing temperature. The extraction rate of taste components in tea liquor reduced with prolonged brewing duration. There are significant effects of different tea shapes, brewing temperature, brewing duration on the concentration of chief taste components in tea liqour. According to the extraction rate of free amino acids, the order of famous green tea is as followed: needle tea(represented by Xinyangmaojian)>straight tea(represented by Xianjuyuhuacha)>curly tea(represented by Biluochun)>bud shaped tea(represented by Zhuyeqing)> flat tea (represented by Xihulongjing)>flower shaped tea(represented by Huangshanmaofeng), the differences among shape treatments were very significant And as to the extraction rate of tea polyphenols, the order of famous green tea is: curly tea>straight tea>needle tea>bud shaped tea>flat tea>flower shaped tea, the differences among shape treatments were very significant. According to the extraction rate of caffeine, the order of famous green tea is:needle tea>straight tea>curly tea>bud shaped tea>flat tea>flower shaped tea, the differences among shape treatments were very significant.The differences of the concentration of chief taste components among three temperature treatments are very significant.According to the relative extraction rate ,when the tea were brewed with 100℃ or 85 ℃ temperature,the order of the taste components is:caffeine>total amino acids>tea polyphenols;when the tea were brewedwith 70 °C temperature,the order of the taste components is:total amino acids>caffeine>tea polyphenols.Thus the relative extraction rate of tea polyphenols is the slowest of all. When brewed with 70 °C temperature, the caffeine infused slowly.Effects of brewing time, brewing duration and different tea shape on extractability of chief taste components were also studied. The results showed that, besides the flower shaped tea, when brewed with 100°C or 85 °C hot water, the concentration of total free amino acids in tea decreased with the increasing brewing times;besides the single bud shaped tea, the concentration of tea polyphenols appeared to attach the peak when brewed with 100°C hot water in their second infusion. The concentration of tea polypenols in Biluochun was as much as 90.55% when brewed five times with 100 °C hot water, and the concentration of tea polypenols in flower shaped tea was between 40% and 48%;The concentration of caffeine decreased with the increasing brewing times in 100 "C.With the expection of Jingxiankuijian, most of the caffeine in the famous tea were extracted after brewing 5 times, which is more than 90% of the total caffeine.The results showed that, there were very significant differences of concentration and extraction of chief taste compenonts among the tea with similar shape. As to the tea with different shape, The differences of extraction of tea polyphenols, total free amino acids are significant, but such difference is more significant than that in tea with similar shape. Thus we concluded that the shape plays an important role in effecting the extractability of chief taste components in famous green tea.Furthermore, The organoleptic evaluation of famous green tea was optimized. Accroding to the various shape, different tea were brewed with various durations to narrow the disparities of extraction among various famous green tea. It is suggested that with 100°C brewing temperature, flower shaped tea should be brewed 6 minutes, curly tea which was fired and stir-fried should be brewed 5mins, single bud shaped green tea and flat tea should be brewed 4mins, curly tea should be brewed 2mins;The optimized method can narrow the disparities of extraction among famous tea with the suitable thickness of tea liquor, thus we concluded that such a method is effective in evaluating the famous green tea.