The Combination of Shaking and Yellow-Light Withering Promote the Volatile Aroma Components and the Aroma Quality of Black Tea

The application of shaking during the withering process has been shown to significantly enhance the floral aroma of black tea. However, prior to this study, there was limited research on the effects of shaking combined with other withering treatments on the aroma components of black tea. In this study, the aroma attributes of black teas processed with shaking combinations of yellow-light or high-temperature withering (YLS, HTS, and HYS) were evaluated through sensory evaluation, and the volatile composition and identification of key aroma compounds in black teas and in-process withered tea leaves were analyzed by gas chromatography-mass spectrometry (GC-MS). The results indicated that black teas subjected to different shaking combinations exhibited a distinct floral aroma with higher volatile compound content, with the YLS treatment showing the most significant aroma improvement. Eight volatile compounds with relative odor activity values (rOAV) > 1 were identified from 53 differential volatile compounds in black tea under different shaking combinations as the most important contributors to aroma quality. Linalool, trans-β-Ionone, α-cedrene, and nonanal were identified as key floral volatiles with high rOAVs. Their concentrations in YLS were notably higher compared to those in S, both in withered tea leaves (with the exception of trans-β-Ionone) and in the final dry black teas, suggesting that there may be a synergistic effect between the yellow-light withering and the shaking process in enhancing these key floral compounds. Overall, this study found that shaking combined with yellow-light withering can improve the aroma composition and quality of black tea, providing a theoretical basis and practical guidance for the production and optimization of high-aroma black tea.