Authors: LIN-LONG MA, DAN CAO, YAN-LI LIU, ZI-MING GONG, PAN-PAN LIU, XIAO-FANG JIN
Abstract: China is a major producer and consumer of green tea and possesses numerous high-quality tea cultivars, which can be used to make green tea. However, the green teas produced from these tea cultivars vary markedly in aroma. In this study, a sensory evaluation method and headspace solid-phase microextraction combined with GC-MS were employed to determine the primary substances that contribute to the aromas and key differences in the aroma components of green tea produced from 20 tea cultivars. The results revealed 57 major volatile components, among which aldehydes, alcohols, and esters were the most prevalent. For the volatile components, the linalool, nonanal, and geraniol contents were the highest, followed by dimethyl sulfide, methyl salicylate, heptanal, and caproicacidhexneylester. The volatile components varied considerably among the green tea samples, and some contained substances with a high content that gave off unique aromas. The correlation analysis revealed significant correlations between the sensory evaluation scores and contents of linalool, geraniol, methyl salicylate, cis-linalool oxide, 3-carene, phenethyl alcohol, limonene, (Z)-3-cis-3-hexenyl isovalerate, citral, (E)-ß-ocimene, alcohols, esters, and alkenes, as well as between the sensory evaluation scores and total volatile component contents. Aromatic substances with the highest odor activity values were, in descending order, linalool, capraldehyde, dimethyl sulfide, ß-ionone, geraniol, nonanal, heptanal, (E)-2-nonenal, and caproicacidhexneylester. These substances were the major contributors to aroma formation in the green tea samples. The principal component analysis and orthogonal projections to the latent structure-discriminant analysis suggested that the 20 tea cultivars could be grouped into 6 categories and that the high content of linalool, nonanal, and geraniol substantially contributed to the categorization of the tea cultivars. A key variable analysis revealed that 23 volatile components played a critical role in the categorization of the tea cultivars.
Keywords: Tea cultivars, green tea, volatile components, odor activity value, principal component analysis
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