Effect of high hydrostatic pressure on whey protein concentrate functional properties

After high hydrostatic pressure (HHP) treatment at 600 MPa and 50°C for 30 min to whey protein concentrate (WPC), there were decreases in protein solubility at pH 4.6, and increases in aggregation and denaturation of whey proteins, especially at high WPC concentrations. During the come-up time of HHP treatment, dissociation of aggregates and formation of dimers were observed. With increasing HHP treatment time, monomers of beta-lactoglobulin (beta-LG), alpha-lactalbumin (alpha-LA), and bovine serum albumin (BSA) decreased and aggregates were formed.;An increase in tryptophan intrinsic fluorescence intensity and a 4 nm red-shift were observed after 30 min of treatment, which indicated changes in the polarity of tryptophan residues of whey proteins from a less polar to a more polar environment. HHP treatment for 30 min increased the number of binding sites of WPC for 1-anilino-naphthalene-8-sulfonate (ANS) from 0.16 to 1.10 per molecule of protein. HHP treatments did not show significant influences in the apparent dissociation constant of ANS except a 1.8-fold increase after 30 min HHP treatment. Increased binding affinities of cis-parinaric acid (CPA) were observed after come-up time or 10 min of HHP treatment.;HHP treatments increased the number of binding sites and the apparent dissociation constants of WPC for benzaldehyde. HHP treatment for 10 min increased the binding affinity of WPC for diacetyl, but no significant changes in the number of binding sites were observed after 10 min of HHP treatment. There were increases in the number of binding sites of WPC for heptanone and octanone after HHP treatment for the come-up time.;As observed by headspace analysis, HHP treatments did not result in significant changes in the retention for benzaldehyde in WPC solutions. Flavor retention of 100 ppm and 200 ppm heptanone and octanone in HHP treated (10 min) WPC was significantly lower than in untreated WPC and HHP treated WPC for come-up time or 30 min. Significant decreases were only observed at 100 ppm for flavor retention of nonanone in HHP treated (10 min) WPC solutions. Further research is required to evaluate the full potential of application of HHP to modify functional properties of WPC and its benefits to the food industry.