The effect of high hydrostatic pressure on the structure of whey proteins-guar gum mixture.

The effect of high hydrostatic pressure (HHP) on the structural properties of whey protein concentrate (WPC) and guar gum mixture has been investigated at pH 5. WPC (6 % w/v) and guar gum (0.25 % w/v) mixture was freeze dried after adjusting pH and treated at different pressure levels (0-600 MPa) for 0-30 min. The solubility of treated powders decreased significantly (p < 0.05) as treatment time and pressure levels increased. Thermal analysis showed an increase in denaturation temperature after HHP treatment at 600 MPa. A more crystalline structure was observed in samples treated with 600 MPa for 20 and 30 min. With increasing pressure and time, particle size of the samples increased and the highest particle size was belonged to sample treated at 600 MPa for 30 min (759.66 nm). SEM results exhibited that by applying the pressure, irregularity of shapes and particle size increased while the apparent cracks decreased. FTIR results indicated that HHP treatment changed shift in bond and peak intensity. As reported in the current study, the application of HHP treatment as a green physical technology on protein-polysaccharide mixture could be used to improve interaction of protein and polysaccharide.