In vitro immuno-modulatory ability of tryptic caseinate hydrolysate affected by prior caseinate glycation using the Maillard reaction or transglutaminase

Abstract

Caseinate was glycated by lactose and oligochitosan via the Maillard reaction and transglutaminase catalysis to yield two glycated caseinates (GC-I and GC-II), followed by trypsin hydrolysis to generate GC-I hydrolysate and GC-II hydrolysate, respectively. In comparison with caseinate hydrolysate, only GC-I hydrolysate showed decreased His, Lys, Tyr, and Val contents. All three hydrolysates in dose-dependent manner exerted in vitro immuno-modulatory abilities via activating three immune cells in terms of lymphocytes, macrophages, and natural killer (NK) cells, enhancing the secretion of seven cytokines in lymphocytes and macrophages, but inhibiting the secretion of one cytokine (interleukine-4) in splenocytes. However, GC-I hydrolysate and GC-II hydrolysate showed respective lower and higher immuno-modulatory abilities than caseinate hydrolysate in the most cases. Amino acid losses of GC-I hydrolysate made partially contribution to its impaired immuno-modulatory ability. It is concluded that lactose glycation and oligochitosan glycation of caseinate could lessen and enhance immuno-modulation of tryptic caseinate hydrolysate, respectively.