Metabolomics-based elucidation of the chemical basis under-lying seasonal variations in sensory quality of Goldsands Black Tea

Goldsands Black Tea (GBT), a premium black tea from northern Guangdong, exhibits seasonal sensory variations with unclear chemical basis. This study integrated sensory evaluation, volatile and untargeted metabolomics to characterize the flavor profiles of spring, summer, and autumn GBTs. Spring tea achieved the highest sensory score, characterized by sweet aroma and fresh, mellow taste; autumn tea presented complex floral-fruity notes; summer tea showed pronounced astringency. Volatile metabolomics identified 66 compounds, with nine showing significant seasonal differences. Five compounds—geraniol, methyl salicylate, linalool, (E)-β-ionone, and β-myrcene—were key aroma contributors. 82 core differential compounds were identified from 9894 ion features detected by non-volatile metabolomics. Amino acids accumulated predominantly in spring tea, positively correlating with freshness/sweetness, while flavonoids accumulated in summer/autumn teas, positively correlating with astringency. Pathway analysis identified phenylpropanoid metabolism, amino acid metabolism, and flavonoid biosynthesis as key regulatory pathways. This study provides initial insights into the chemical basis of seasonal quality variations and offers guidance for optimizing production.