Hydrolysis of Soybean and Rapeseed Proteins with Enzyme Complex Extracted from the Pyloric Caeca of the Cod

Abstract

Hydrolysis of soybean and rapeseed proteins with extract from cod pyloric caeca has been performed. The hydrolysates were analyzed by SDS-PAGE, HPLC, amino acid analysis, and mass spectrometry. The degree of hydrolysis depended on the substrate/enzyme extract ratio, hydrolysis time, temperature, and protein concentration. The hydrolysis of soybean and rapeseed proteins at a substrate/enzyme extract ratio of 1 : 20 and a hydrolysis time of 20 h at 37°C led to complete cleavage of intact proteins. The soluble part of the rapeseed protein hydrolysate consisted of oligopeptides with a molecular weight of less than 14 kDa, as well as free amino acids and short peptides. In sum it was 77% of the original protein material (including 6% of the free amino acids). According to the results of the amino acid analysis, the soluble part of the soybean proteins hydrolysate contained a set of oligopeptides and free amino acids, which comprised 83% of the starting protein material (including 20.16% of the free amino acids).