Effects of Plucking Standards and Processing Methods on the Quality Characteristics of Summer Tea Leaves

To improve the utilization value of summer tea resources, fresh summer tea leaves with different plucking standards were processed into four tea types (green, yellow, white, and black teas) to elucidate the effects of plucking maturity and processing methods on tea quality. Sensory evaluation, physicochemical analysis, electronic tongue, and metabolomics were employed to comprehensively characterize tea quality attributes. The tea samples made from one bud and one leaf showed superior sensory quality, especially in aroma, freshness, and sweetness. Processing significantly shaped flavor profiles: black tea reduced bitterness, white and yellow tea enhanced sweetness and umami, and green tea exhibited stronger umami and astringency characteristics. White and black tea processing also promoted key metabolite accumulation. Based on TAV (taste activity value) and rOAV (relative odor activity value), 10 key taste compounds (e.g., Asp, Glu, Thea, EGCG) and 10 key volatile metabolites (e.g., geraniol and dihydro-2-methyl-3(2H)-furanone) were identified, providing insights into the chemical mechanisms underlying tea quality development. The differential accumulation of taste compounds influenced taste characteristics, while variations in volatile metabolitescontributed to aroma diversity induced by different processing methods.