Protein denaturation and functional properties of Lenient Steam Injection heat treated whey protein concentrate

Whey protein concentrate (WPC) was heat treated by use of the novel heat treatment method of Lenient Steam Injection (LSI) to elucidate new functional properties in relation to heat-induced gelation of heat treated WPC. Denaturation was measured by both DSC and FPLC, and the results of the two methods were highly correlated. Temperatures of up to 90°C were applicable using LSI, whereas only 68°C could be reached by plate heat exchange before coagulation/fouling. Denaturation of whey proteins increased with increasing heat treatment temperature up to a degree of 30–35% denaturation at 90°C LSI treatment. A subsequent spray drying was found not to affect the degree of denaturation. WPC gels were found to become softer, as function of increasing temperature during LSI treatment of WPC. Furthermore, pH and conductivity of WPC largely affected both the axial stress and the Hencky strain of WPC gels. Due to the wide application of whey proteins as functional ingredients in foods, the investigation of new functionalities of WPC is highly significant. Very little has been published on direct heat treatment of WPC, and the impact hereof on the functionalities of WPC is novel to the food industry. ► Lenient Steam Injection provides a gentle heat treatment of WPC. ► The functionality of WPC evaluated as gel texture changed upon LSI treatment. ► Increased denaturation of whey proteins lead to decrease in gel strength.