Metabolic insights into the enhanced umami and sweetness of small-leaf yellow tea from albino cultivars

Albino cultivars are well suited for producing small-leaf yellow tea because of their unique leaf colour and taste. This study aimed to uncover the chemical basis for the fresh sweet taste and low bitterness/astringency of albino cultivars through metabolomics. We identified 20 core taste compounds, namely 13 flavonoids, 5 amino acids (AAs), and 2 catechins. Compared with the control 'Fudingdabaicha', 'Naibai' contained a higher number of umami AAs (theanine: 45.84 mg/g; glutamic acid: 10.27 mg/g) and lower catechin levels. Quantitative descriptive analysis showed that albino cultivars exhibited stronger umami and sweetness but reduced bitterness and astringency, suggesting that umami compounds can mitigate the perception of bitterness and astringency. Weighted gene co-expression network analysis indicated that AAs are associated with umami taste, whereas flavonoids, catechins, and caffeine influence bitterness and astringency. These findings support the conclusion that the combination of elevated AA levels and reduced catechin levels is the primary driver of the fresh sweet taste of albino cultivars.