Limited hydrolysis of rice endosperm protein for improved techno-functional properties

Limited hydrolysis of rice endosperm protein isolate was carried out with acid and neutral endoproteases to evaluate the relationship between degree of hydrolysis and techno-functional properties. The highest studied degree of hydrolysis was 5.4% corresponding to 55.2% protein solubility. Solubility increased as a function of degree of hydrolysis with higher efficiency by acid endoprotease. Colloidal stability of the protein suspensions steadily increased with increasing degree of hydrolysis. Higher colloidal stability values were achieved by neutral endoprotease (31-89%) compared to that by acid endoprotease (20-75%). On the other hand, the absolute values of zeta potential and surface hydrophobicity decreased as a function of degree of hydrolysis leading to higher values by neutral endoprotease (-21.4 mV and 21.7 mV) than by acid endoprotease (-813.4 mV and 11.7 mV). Foaming, gel formation and water holding properties improved only until degree of hydrolysis values of 1.5% (neural endoprotease) and 1.9% (acid endoprotease).