High pressure microfluidization treatment of heat denatured whey proteins for improved functionality

Abstract

Solutions (5% protein) of a whey protein concentrate (WPC) in fresh acid whey or in water, as well as the fresh whey alone, were adjusted to pH 5.8, 4.8 or 3.8, heat treated at 90 °C for 10 min and further exposed to high pressure (150 MPa) microfluidization treatment. The volumes of sediment after centrifugation were recorded as a measure of the degree of insolubility of the proteins. Microfluidization disrupted the heat-induced aggregates into non-sedimenting whey protein polymers so that in some cases, especially at pH 3.8, the products studied were almost completely resistant to sedimentation after the microfluidization treatments. Heat denatured/microfluidized whey proteins reaggregated upon subsequent heating, with the pH having a major impact on the amount of sediment produced. Microfluidization of aqueous WPC solutions heat-treated before spray- or freeze-drying substantially increased the solubility of the powders upon reconstitution. Heat-induced viscoelastic gels were produced from freeze-dried microfluidized samples processed at pH 3.8 and reconstituted to solutions containing 12% (w/w) protein.