Withering time determines shaking-driven flavor restructuring in Xinyang white tea

To elucidate the interactive effects of withering time and shaking frequency on flavor formation in white tea, twelve processing combinations comprising three withering durations (12, 24, and 36 h) and four shaking levels (0, 1, 2, and 3 cycles) were investigated. Tea quality was evaluated using sensory evaluation, electronic tongue analysis, physicochemical analyses, computer vision, and purge–and–trap gas chromatography–mass spectrometry (P&T–GC–MS), with analysis of variance–simultaneous component analysis (ASCA) used to assess the main and interactive effects of the two processing factors. ASCA revealed significant effects of withering time, shaking frequency, and their interaction on the volatile profile, indicating that the response to shaking depended on withering duration. Sensory quality was primarily influenced by shaking frequency, with W24-2 achieving the highest overall sensory score. Shaking was associated with changes in esterified catechins, soluble sugars, and free amino acids, corresponding to reduced bitterness and astringency and enhanced sweetness and umami. Three cycles of shaking treatment marked the transition of infusion color from apricot-yellow to reddish-brown. Although shaking generally decreased total volatile abundance, it increased the relative abundance of certain esters and aldehydes associated with floral and fruity aromas. Overall, withering duration modulated the flavor response of white tea to shaking, highlighting the importance of coordinating the two processing factors for targeted flavor regulation.