The impact of caseinate oligochitosan-glycation by transglutaminase on amino acid compositions and immune-promoting activity in BALB/c mice of the tryptic caseinate hydrolysate.

Caseinate was glycated with oligochitosan via transglutaminase (TGase) action and then hydrolyzed by trypsin to generate glycated caseinate hydrolysate (GCNH) that was investigated for in vivo immune-promoting activity. Caseinate hydrolysate (CNH) containing glucosamine of 5.7 g/kg had amino acid compositions similar to GCNH. In normal BALB/c mice, GCNH at 100-400 mg/(kg d) showed higher immune-promoting activity than CNH via increasing serum IgM, IgA, and IgG by 1.5-24.5%, enhancing spleen and thymus indices by 9.7-26.2%, or increasing splenocyte lymphocyte proliferation and natural killer (NK) cell activity by 1.2-11.5%. GCNH also exerted higher activity than CNH in the suppressed BALB/c mice through increasing serum IgM, IgA, and IgG by 2.6-10.5%, enhancing spleen and thymus indices by 0.4-50.1%, or increasing splenocyte lymphocyte proliferation and NK cell activity by 3.4-18.9%. The results highlight that this TGase-type oligochitosan-glycation is potential to generate functional protein ingredients that possess improved immune-promoting activity once hydrolyzed by trypsin.