Abstract: After being subjected to different pasteurization treatments (63 ℃/30 min, 72 ℃/15 s and 85 ℃/15 s), bovine lactoferrin was digested in vitro in a simulated infant gastrointestinal environment. The resulting hydrolysates were separately used to challenge rat intestinal crypt epithelial cells (IEC-6) to evaluate their immunological activity. The results showed that all the three lactoferrin hydrolysates could promote small intestinal cell proliferation in a dose-dependent manner. Flow cytometry results demonstrated that these hydrolysates increased the percentage of IEC-6 cells in the G2/M and S phase and reduced cell apoptosis. The results of reverse transcription real-time quantitative PCR (RT-qPCR) indicated that the lactoferrin hydrolysates elevated the expression levels of cyclin B1, CDK1 and cyclin E1 and reduced the expression level of p21. Taken together, we found that that pasteurization could completely inactivate the active group of bovine lactoferrin. The two pasteurization treatments, 72 ℃/15 s and 85 ℃/15 s, especially the latter, could ensure food safety while maintaining the immunological activity of lactoferrin to the utmost extent. The best concentration to promote intestinal immunity was 0.1 mg/mL for all the lactoferrin hydrolysates.

Key words: lactoferrin, pasteurization, intestinal immunity