Three sources of food proteins were treated with microbial transglutaminase (EC 2.3.2.13) in order to assess changes in the physicochemical properties of reactivity, solubility, emulsification, and free amino groups of the formed polymers. Samples of lactic casein (LC), isolated soy protein (ISP), and hydrolysed animal protein (HAP), were incubated with the enzyme for one or two hours. LC and ISP showed a reduced solubility of 15% and 24% respectively, with HAP showing no alteration on solubility. Amino nitrogen content was 7%, 3% and 2% reduced for HAP, LC and ISP respectively. LC and ISP demonstrated lower emulsifying activity when they were enzymatically treated but the formed emulsions were stable, contrasting with HAP, which exhibited no changes in emulsifying properties.
transglutaminase; food proteins; functional properties of proteins
