Effect of processing methods on the phytochemicals, digestion behaviors, and nutraceutical potential of Yunnan large-leaf tea: A combined in vitro and in vivo study.

Low-fermentation teas (GT, WT, YT, and rawPT) displayed highly similar phytochemical profiles both before and after digestion, whereas BT and ripePT showed distinct compositions and different post-digestion stability.

• Six teas produced from the same batch of fresh leaves were compared: green tea (GT), white tea (WT), yellow tea (YT), black tea (BT), raw Pu-erh tea (rawPT), and ripe Pu-erh tea (ripePT).
• An INFOGEST-based simulated digestion model combined with LC-MS/MS untargeted metabolomics was used to characterize digestion-induced phytochemical changes.
• The grouping pattern of low-fermentation teas vs. highly fermented teas was consistent both before and after digestion.

Gastrointestinal digestion caused extensive degradation of flavonoids and monomeric polyphenols, which correlated with diminished antioxidant capacity.

• Untargeted metabolomics confirmed extensive degradation of flavonoids and monomeric polyphenols during digestion.
• The degradation of these compounds was correlated with diminished antioxidant capacity after digestion.
• HPLC analysis was used alongside metabolomics to quantify these changes.

Alkaloids and residual phenolic acids retained structural stability throughout gastrointestinal digestion.

• Unlike flavonoids and monomeric polyphenols, alkaloids and phenolic acids were stable across the gastrointestinal digestion process.
• Based on metabolomic screening, sixteen potential bioactive compounds were identified.
• Targeted HPLC demonstrated that phenolic acids and catechins were the main active substances of GT after digestion, while alkaloids were the primary active substances of ripePT after digestion.

Fermented teas (ripePT and BT) enhanced gut microbiota diversity and promoted production of short-chain fatty acids, especially butyrate, in animal studies.

• Animal studies demonstrated that fermented teas (ripePT and BT) exhibited unique effects on gut health.
• Effects included enhancing gut microbiota diversity and promoting the production of short-chain fatty acids (SCFAs), especially butyrate.
• These effects were closely associated with selective enrichment of beneficial microbial taxa including Ligilactobacillus, Akkermansia, Dubosiella, Bifidobacterium, and Lachnospiraceae_NK4A136_group.

Metabolomic screening identified sixteen potential bioactive compounds across the six tea types before and after digestion.

• LC-MS/MS untargeted metabolomics was used to screen for bioactive compounds.
• Sixteen potential bioactive compounds were identified through metabolomic screening.
• These compounds were further characterized using targeted HPLC analysis.

Processing methods significantly modulate the phytochemical composition of Yunnan large-leaf tea, influencing digestion stability and gut health potential.

• All six teas were produced from the same batch of fresh leaves, isolating processing method as the variable.
• The degree of fermentation was a key factor distinguishing phytochemical profiles, with BT and ripePT showing distinct compositions compared to less-fermented teas.
• The study used a combined in vitro (INFOGEST simulated digestion, LC-MS/MS, HPLC) and in vivo (animal studies) approach.