Property modification of caseinate responsible to transglutaminase-induced glycosylation and crosslinking in the presence of a degraded chitosan

Transglutaminase at a concentration of 10 kU/kg of protein and degraded chitosan were used for glycosylation and crosslinking of caseinate at a fixed molar ratio of the acyl acceptor to the acyl donor of 3:1, a protein concentration of 50 g/L, a pH 7.5 at 37°C, and a reaction time of 4 h. Electrophoretic and chemical analyses showed glycosylation and crosslinking of caseinate. Glycosylated and crosslinked caseinate (GC-caseinate) contained glucosamine at 12.77 g/kg of protein, and the protein fraction had fewer reactable amino groups than original caseinate (0.58 vs. 0.64 mol/kg of protein). GC-caseinate exhibited an enhanced surface hydrophobicity, in vitro digestibility, water-binding capacity, and rheological properties, with poor protein dispensability and emulsification activity, but a similar oilbinding capacity and emulsion stability, compared with original caseinate. GC-caseinate also exhibited better properties than transglutaminase-crosslinked caseinate. Glycosylation and crosslinking was effective for better water-binding and rheological properties of caseinate.