Exploration of the sweetness and sweet aroma of large-leaf tea: Comprehensive analysis using widely targeted metabolomics and sensory evaluation.

Sweetness and sweet aroma are key quality attributes of high-quality tea, significantly influencing consumer preferences and market value. However, the metabolic mechanism of sweetness and sweet aroma in different tea types remains unknown. The objective of this study was to elucidate the metabolic basis underlying the formation of sweetness and sweet aroma in different tea types. Large-leaf tea leaves were processed into green, black, white, yellow, and oolong teas, then subjected to traditional sensory evaluation and metabolomics analysis. The results revealed that black tea (BT) and white tea (WT) exhibited notably stronger sweet tastes and aromas compared to other tea types. These teas contained significantly higher concentrations of sweet-tasting metabolites, including d-glucose, inositol, d-fructose, and D-galactose, along with lower concentrations of bitter compounds such as L-histidine and catechins. In terms of aroma, 5-ethyl-3-hydroxy-4-methyl-2(5H)-guranone, dihydro-2-methyl-3(2H)-furanone, furaneol, tetrahydro-4-methyl-2-(2-methyl-1-propenyl)-2H-pyran, 4-methoxy-benzaldehyde, and paraldehyde were identified as common key contributors to sweet aroma across all five tea types. Specifically, tetrahydro-4-methyl-2-(2-methyl-1-propenyl)-2H-pyran, 1-hexanol, and 3-methylbutyl acetate were associated with the enhanced sweet aroma in BT and WT. In conclusion, this study identified key differential metabolites and metabolic pathways responsible for the superior sweetness and sweet aroma of BT and WT. These findings provide valuable theoretical insights and scientific guidance for improving tea quality and developing premium tea products.