Enzymatic hydrolysis of okara protein concentrate by mixture of endo and exopeptidase

Abstract

The objective of this study was to obtain a model and optimize the enzymatic hydrolysis of okara protein concentrate using a combined mixture of alcalase and flavourzyme. The highest degree of hydrolysis (DH) was 22% obtained at 40°C, enzyme/substrate ratio of 5 g/100 g protein, pH of 7.1, and alcalase/flavourzyme ratio of 90%/10%. Additionally, under optimal condition, protein hydrolysates with DH 0, 6, 12, 18, and 22% were obtained and analyzed. Protein hydrolysis was confirmed by the electrophoretic profile, which showed diffuse bands with smaller molecular weight. The total amino acid profile showed that the protein hydrolysate with DH 22% had a balanced composition of all essential amino acids. All protein hydrolysates contained threefold higher aglycone isoflavone content than the okara protein concentrate. Enzymatic hydrolysis enhanced the antioxidant capacity of the protein hydrolysates, which was approximately 2.3- and 2.7-fold higher according to ABTS and FRAP analyses, respectively, compared to the intact protein. Thus, the protein hydrolysate can be incorporated into real food systems as a natural antioxidant alternative to the synthetic compounds. Practical applications Bioactive compounds have increasingly been studied due to their beneficial effects, such as antioxidant capacity. Therefore, it is necessary to research how to obtain these bioactive compounds and what are the most important parameters to obtain an efficient process. Most papers evaluated the hydrolysis process using only one enzyme. In this work, a central composite rotatable design was carried out to optimize the use of two enzymes with different specificities to obtain bioactive compounds with high antioxidant capacity.