High hydrostatic pressure assisted enzymatic hydrolysis of whey proteins

Abstract

Whey proteins, dueto their high nutritional value, are generally hydrolyzed to reduce the allergenicity and used as ingredients in many special products, such as infant formulae, geriatric products, high energy supplements or dietetic foods or in foods produced to prevent nutrition related diseases, like food intolerances and allergies. The aim of this work was to assess the applicability of innovative treatments, such as highhydrostatic pressure (HHP) processes, to assist the enzymatic hydrolysis of target proteins, such as whey protein concentrate (WPC-80), in order to modify their antigenicity. Experiments were carried out to verify the effectiveness of HHP technology to accelerate whey protein hydrolysis reaction with selected enzymes (á-chymotrypsin, bromelain), and to affect the protein allergenic power. For this purpose, different HHP treatments were carried out at several pressure level (100, 200, 300 and 400 MPa) and the untreated whey protein samples were used as control. A defined enzyme/substrate ratio of 1/10 w/w was used in the experiments, while the treatment time was changed from 0 to 30 minutes (0, 5, 15, or 30 min). The experimental data demonstrated that High Hydrostatic Pressure (HHP) induced WPC-80 unfolding,at the highest pressure level applied (400 MPa) as indicated by the high erexposure of free sulfhydryl groups. When HHP was combined with enzymatic hydrolysis, the degree of hydrolysis increased not only with the pressure level applied but also with the processing time. These results suggest that, even if the exposure of hidden epitopes upon protein unfolding increased the antigenicity of whey proteins, further peptide bonds cleavage also takes place after hydrolysis. This effect could modify whey proteins antigenic sequences, and thus their antigenic power.