关键词: 红茶；九曲红梅茶；感官品质；香气；滋味；气相色谱-质谱

Abstract: The flavor quality of Jiuqu Hongmei tea processed by a new technology has been demonstrated to be better than that of the one processed by the traditional procedure, but the flavor chemistry characteristics of the new product are not clear yet. In this study, new Jiuqu Hongmei tea samples of different quality grades and traditional Jiuqu Hongmei tea samples were prepared for sensory evaluation following the national standard of China and for measurement of the contents of non-volatile compounds such as water extract, tea polyphenols, free amino acids, caffeine, theaflavins, thearubigins and theabrownins. Also, we analyzed the volatile composition by gas chromatography and mass spectrometry (GC-MS). The results showed that the new tea had a sweet and mellow taste and a high and fresh aroma and it contained less free amino acids and caffeine than the traditional one. Free amino acids, theaflavins, thearubigins and theabrownins were found to be the key taste compounds to differentiate different grades of Jiuqu Hongmei tea. A total of 39 volatile compounds were identified from Jiuqu Hongmei tea, among which dominant were geraniol, linalool, phenylethyl alcohol, benzyl alcohol, benzene acetaldehyde, benzaldehyde, trans,trans-2,4-heptadienal, β-ionone, methyl salicylate, cis-hexanoic acid, 3-hexenyl ester and geranic acid. As the quality grade of new Jiuqu Hongmei tea dropped, the contents of geraniol, nerol, benzene acetaldehyde, nonanal, 3,5-octadien-2-one, 3-octen-2-one and trans-β-ocimene were decreased while the contents of benzyl alcohol, nerolidol, hotrienol, trans-linalol oxide IV, β-cyclocitral, decanal, trans-2-hexenal, cis-jasmone and dihydro actinidiolide were increased. Therefore, Jiuqu Hongmei tea of different quality grades should be manufactured by the new technology of oxygen-supply fermentation according to the characteristics of raw materials.

Key words: black tea; Jiuqu Hongmei tea; sensory quality; aroma; taste; gas chromatography-mass spectrometry