Structure and property modification of an oligochitosan-glycosylated and crosslinked soybean protein generated by microbial transglutaminase.

The impacts of oligochitosan glycosylation and crosslinking on the structure and properties of a soybean protein were investigated. The reaction was carried out by transglutaminase with 10 kU kg(-1) protein at pH 7.5 and 37°C for 3h, under a protein content of 40 gl(-1) and a molar ratio of acyl donor to oligochitosan acceptor of 1:3. The modified protein contained glucosamine at a concentration of 12.1 g kg(-1) protein. Electrophoresis and infrared spectroscopy analysis confirmed the modified protein to be crosslinked and glycosylated. Circular dichroism analysis showed the modified protein possessed a decreased α-helix and β-structure. The modified protein exhibited lower surface hydrophobicity and emulsifying activity but higher emulsion stability than the soybean protein, it also had better water and oil binding capacity (12.2g and 3.5 ml g(-1) protein, respectively), and could form a thicker protein outer layer in the oil droplets in emulsion. Transglutaminase-induced oligochitosan glycosylation and crosslinking is thus able to modify soybean proteins.