Influence of Ventilation Level during Yellowing on the Quality of Yellow Tea

To investigate the impact of different ventilation levels during the yellowing process on the quality of yellow tea, fresh leaves of the tea cultivars ‘Baiye 1’ and ‘Yingshuang’ were selected and each cultivar was subjected to three yellowing treatments: gauze bagging (A), gauze + kraft paper bagging (B), and vacuum bagging (C). The differences in non-volatile components, volatile components, and sensory quality were analyzed among the six tea samples. The results showed that vacuum bagging increased the contents of tea polyphenols, free amino acids, and reducing sugars, promoted the accumulation of non-ester catechins, increased the content of sweet amino acids, and upregulated the levels of floral volatile substances such as linalool. In addition, it effectively improved the sensory quality; the prepared tea infusion exhibited a bright yellow color, a rich and long-lasting aroma, and a mellow, fresh and brisk taste. Therefore, vacuum yellowing treatment improves the quality of yellow tea to some extent.