Label-free quantification proteomics reveals the active peptides from protein degradation during anaerobic fermentation of tea

Although active peptide is an important functional component, the mechanism of releasing peptides promoted by the degradation of tea protein during fermentation is still unclear. The profiles of peptides and tea proteins in pickled tea during anaerobic fermentation were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results showed that water-soluble proteins are the main target of hydrolysis in the fermentation, and the degradation of tea protein clusters at different fermentation time triggers the continuous release of peptides. ILW, WLR, WY, YV, ELW, FY, and PYV are considered to be the key peptides related to the antioxidant activity of pickled tea, and enzyme proteins especially rubisco and tubulin family proteins may be responsible for the release of these potential antioxidant peptides. Peptides derived from tea proteins are suggested to be one of the key antioxidants in pickled tea. The findings can promote to targeted degradation of tea protein to increase the active peptides and function in microbial fermented tea.