Differences in Free Amino Acids and Total Nitrogen Contents among Various Prices of Green Tea
Author: Toshihiro MUKAI and Hideki HORIE and Tetsuhisa GOTO
Sixty one green tea samples with price ranging from 560 to 12, 000 yen/kg were collected and the contents of total nitrogen and individual free amino acids were determined. There was no difference in their glutamic acid contents between samples, however theanine, glutamine and arginine contents varied significantly depending on the price of green tea. Among the higher price teas, glutamine was more than glutamic acid, while in lower price teas it was the reverse. Among low and middle price teas, the price corelated to total nitrogen content, while teas with high price, no corelation was observed. Therefore, it seemed to be impossible to estimate the quality of high price tea from the total nitrogen content. The higher correlation was observed between price and the content of total free amino acids for wide price range, indicating this might be better indicator for the estimation of the quality of green tea. Among the seventeen amino acids determined in the present study, arginine and theanine showed the highest correlation between their contents and the price of green tea.