Enzymatic Hydrolysis of Soy Protein Isolate by Food Grade Proteinases and Aminopeptidases of Plant Origin

Abstract

ABSTRACTEnzymatic hydrolysates of soy protein isolate were prepared using food grade proteinases and aminopeptidases entirely of plant origin. Papain from papaya fruit and bromelain from pineapple stem (both as catalog products and lyophilized crude extracts) were applied (20 mAU.g−1 substrate) in the first hydrolysis stage. Aminopeptidase (0.1 units.g−1 substrate) and proline iminopeptidase (0.08 units.g−1 substrate) from cabbage leaves (Brassica oleraceae var. capitata) and aminopeptidase (0.5 units. g−1 substrate) from chick-pea cotyledons (Cicer arietinum L.) were involved in the debittering process by additional hydrolysis of the peptide mixtures. The degree of hydrolysis was estimated from the amino nitrogen content and a level of36-38% degree of hydrolysis ensured an acceptable bland taste. Gel chromatography on BioGel P-2 of the obtained soy protein hydrolysates indicated a molecular weight of the all released peptides under 800 Da. Using entirely enzymes of plant origin the prepared hydrolysates are suitable for food supplements covering the requirements of vegetarians as well as the religious tolerance. The soy protein hydrolysates manifesting bland taste present a good substance for further design of food supplements with natural plant extracts from Vietnam.