Abstract:
This study aimed to address the inherent limitations of traditional manual Zuoqing (shaking and withering stage) in Guangdong Dancong tea, including its heavy reliance on empirical expertise, the lack of quantitative indicators, and the absence of controllable processing mechanisms. Three representative cultivars from majoy Dancong-producing areas were used as experimental materials. We utilized self-developed controlled equipment for the shaking and withering stage to compare the effects of automated versus manual processing on the flavor profile of the tea. The flavor characteristics were comprehensively analyzed through sensory evaluation, quantification of key components (polyphenols, caffeine, and amino acids), electronic nose (E-nose), and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS), coupled with multivariate statistical analysis. The results indicated that while Dancong tea varieties exhibited distinct cultivar-specific aroma and taste profiles, the two processing methods exerted minimal impact on primary physicochemical indices and overall aroma structures. Controlled shaking and withering consistently maintained the balance of gustatory components and effectively replicated the flavor profile achieved through manual processing. Regarding key volatile organic compounds (VOCs), Yinhua-scented Dancong was characterized by high odor activity values (OAVs) of jasmone, methyl jasmonate, and indole, which formed its signature honeysuckle fragrance. Zhilan-scented Dancong was primarily defined by myrcene, ocimene, linalool, and methyl salicylate, presenting a characteristic orchid fragrance. Meanwhile, Milan-scented Dancong was dominated by geranylacetone,
β-ionone, and dihydroactinidiolide, showing a complex honey-orchid fragrance. Notably, the controlled shaking and withering technology significantly enhanced the OAVs of floral volatiles in Yinhua-scented Dancong and successfully reproduced the aromatic characteristics of manual methods in the other two varieties. These findings demonstrate that precise control over the shaking and withering stage can effectively optimize the formation of key flavor substances, providing a scientific foundation for the standardization and intelligent automation of Dancong tea processing.