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Emulsifying and Foaming Properties of Okara Protein Hydrolysates

Fierens, Ellen, Brijs, Kristof, Delcour, Jan A.
Cereal chemistry 2016 v.93 no.1 pp. 71-76
chemical precipitation, coproducts, emulsifying, emulsifying properties, emulsions, enzymes, foaming properties, hydrolysates, hydrolysis, milk production, protein hydrolysates, protein isolates, sodium hydroxide, solubility, soymilk
Okara is a low-value coproduct of soy milk production. Its dry matter contains 25–30% protein that is of high nutritive quality, has an excellent efficiency ratio, and thus holds promise for applications in food systems. However, okara protein has low solubility. We here optimized its extraction and isolation from okara by using dilute sodium hydroxide and subsequent isoelectric precipitation. The obtained okara protein isolate (OPI) was hydrolyzed with different enzymes into a range of hydrolysates with different degrees of hydrolysis. Most hydrolysates had better emulsifying activity and produced more stable emulsions than OPI. In contrast, hydrolysis had no positive effect on foam-forming and foam-stabilizing activity of OPI proteins. Hydrolysis of OPI enhances the emulsifying capacity of the proteins. Furthermore, the emulsifying and foam-forming capacities of most of the OPI hydrolysates were similar to or even better than those of the commercial (soy) protein hydrolysates used in this study.