Insights into in vitro digestion properties and peptide profiling of Chinese rubing PDO cheese prepared using different acidification technology

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Rubing cheese is a traditional Chinese Protected Designation of Origin (PDO) cheese consumed for more than six hundred years, but to date, the digestion properties and peptide profiling during simulated gastrointestinal digestion are still uncertain. This study aimed to investigate the effects of traditional direct acidification technology (TRB) and fermentation acidification technology on digestion properties and peptide profiling of rubing cheese (FRB) proteins after simulated gastrointestinal digestion by protein digestomics, coupled with bioinformatic in silico analyses to identify potential bioactive peptides. The results demonstrated that FRB could significantly improve the in vitro digestibility, protein degradation, and polypeptide content than TRB (P ＜ 0.05). Furthermore, a total of 369 and 332 peptides were identified in FRB- and TRB-pancreatic digests, respectively, using LC-MS/MS. FRB could release more low molecular weight peptides of 400–1200 Da from α-casein and β-casein after digestion. These low peptides included 16 reported potential ACEIPs (angiotensin I-converting enzyme inhibitory peptides), 11 dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides, and 6 antioxidant peptides, while TRB contained more than the reported potential antimicrobial peptides (10). In vitro activity determination showed that FRB had significantly higher ACEI, α-glucosidase inhibitory, and antioxidant activities than TRB during the entire digestion time (P ＜ 0.05), which was correlated to the reported potential bioactive peptides released during the digestion of FRB. Our study is the most comprehensive protein digestomic analysis of Chinese rubing cheese to date and provides a new positive outlook on rubing cheese consumption.