Arginine prevents thermal aggregation of hen egg white proteins

The control of aggregation and solubilization of hen egg white protein (HEWP) is an important issue for industrial applications of one of the most familiar food protein sources. Here, we investigated the effects of edible amino acids on heat-induced aggregation of HEWP. The addition of 0.6 M arginine (Mg) completely suppressed the formation of insoluble aggregates of 1 mgL(-1) HEWP following heat treatment, even at 90 degrees C for 20 min. In contrast, lysine (Lys), glycine (Gly), and sodium chloride (NaCl) did little to suppress the aggregation of HEWP under the same conditions. SDS-PAGE indicated that Arg suppresses the thermal aggregation of almost all types of HEWP at 1 mg mL(-1). However, Arg did not suppress the thermal aggregation of HEWP at concentrations 10 mg mL(-1) and prompted the formation of aggregates. Transmission electron micrographs revealed a high-density structure of unfolded proteins in the presence of Mg. These results indicate that Arg exerts a greater suppressive effect on a protein mixture, such as HEWP, than on a single model protein. These observations may propose Arg as a safe and reasonable additive to HEWP for the elimination of microorganisms by allowing an increase in sterilization temperature.