Flavor and Amino Acids of Brewed White Teas

Flavor of the brewed white tea in relation to its constituents of free amino acids (FAA) was studied. The descriptive statistics, ANOVA, principal component analysis(PCA), and linear category identification were applied for the analysis. The FAA contents on 46 samples collected from 3 white tea-producing areas in the province were determined by using an automated analyzer. The results showed that(1)the total FAA in the tea ranged from 16.19 mgg-1 to 51.00 mgg-1, with an average of 39.36 mgg-1; (2) the highest FAA content of(45.788.39)mgg-1 was found in Kung Mee tea, followed by that of Silver Needle Pekoe tea at(38.156.12)mgg-1, while the lowest was White Peony tea at(34.019.16)mgg-1; (3) theanine in the tea accounted for 52.90% of the total FAA contributing to the cool and delightful taste of the tea; (4) proline, glycine, aspartic, and threonine were the main source of the sweetness of Silver Needle Pekoe tea; (5) leucine, histidine, and methionine brought about the hint of bitterness in Silver Needle Pekoe tea; (6) proline, valine, aspartic, and alanine gave the sweet note in Kung Mee tea; (7) phenylalanine, isoleucine, leucine, and valine tended to be slightly bitter on the taste; and, (8) glutamic acid might render the umami and sour tastes in Silver Needle Pekoe and Kung Mee teas; (9)the correct rate in classifying the white teas based on FAA constituents was found to be 100%. Subsequently,using the same model, 27 commercial samples of Kung Mee, Silver Needle Pekoe, and White Peony teas were evaluated to show the rates of correct identification to be 100%, 88.89%, and 88.89%, respectively. It was, thus, concluded that FAA composition of the 4 categories of amino acids in tea, combined with PCA and LDA analytical methods, could be used to accurately distinguish the white teas.