Effects of Different Tea Varieties on the Quality of Enshi Yulu Tea

To investigate the effects of tea varieties on the quality of Enshi Yulu tea, 10 main tea cultivars (Fuyun 6, Echa 1, Chunbolü, Zhenong 117, Longjing 43, Wuniuzao, Zhongcha 108, Echa 10, Zhuyeqi, and Fuding Dabai) grown in Enshi were processed into Yulu tea, which was then evaluated for sensory quality, major physicochemical quality components (tea polyphenols, free amino acids, water extracts, and chlorophylls), dry tea color parameters (L*, a*, and b*), and volatile components. The results showed that Yulu teas made from different cultivars had their own characteristics. Among the 10 teas, Fuyun 6 had the highest sensory score for appearance with a tight and straight shape and a green color. Echa 1 and Chunbolü had the best mellow and fresh taste. Zhenong 117 had a high and long-lasting chestnut-like aroma with the highest sensory score for aroma. Chemical composition analysis showed that the phenolic/ammonia ratio of each tea was lower than 5, with Fuyun 6 having the lowest value, but not significantly different from Longjing 43. Wuniuzao had the highest soluble sugar content, while Fuyun 6 had the lowest value. Echa 1 had the highest total amount of catechins, followed by Echa 10 and Zhenong 117, while Zhongcha 108 and Wuniuzao had the lowest value. Chunbolü and Echa 1 had the highest ratio of lutein to chlorophyll a plus b, while Longjing 43 had the lowest level. Overall, Longjing 43, Chunbolü and Wuniuzao Yulu teas had better sensory and physicochemical qualities. A total of 98 aroma components were detected in the 10 Yulu teas using headspace solid-phase microextraction (HS-SPME), including 22 alcohols, 13 hydrocarbons, 15 aldehydes, 14 olefins, 16 esters, 6 ketones, 3 halogenated hydrocarbons, 2 phenolic compounds, 1 ether compound, and 6 heterocyclic compounds. Among them, alcohols were the most abundant. Analysis of relative odor activity values (rOAV) revealed that linalool, phenylethanol, geraniol, jasmine, trans-β-ionone and nonanal were the major contributors to the characteristic aroma of the 10 Yulu teas. Totally 17 key differential aroma components among these teas were identified, including benzyl alcohol, linalool, phenylethanol, geraniol, benzaldehyde and nonanal.