High intensity ultrasound effects on heat-induced whey protein isolate gels depend on α-lactalbumin: β-lactoglobulin ratio

Abstract

The effects of high intensity ultrasound (HIU) treatment on physical properties of whey protein isolate (WPI) gels, i.e., water holding capacity, gel strength and elasticity, were studied. WPIs with different α-lactalbumin:β-lactoglobulin (α-la:β-lg) ratios were subjected to ultrasonication (24 kHz, 300 W cm−2, 2078 J mL−1) with and without temperature control, i.e., T < 20 °C and T < 65 °C, respectively. Effects of ultrasonication were greatly affected by the relative amount of α-la, most likely due to the type of interactions formed during gelation after ultrasonication. For WPI with relative high α-la content ultrasonication improved the water holding capacity and gel strength of the heat-induced gels. To the contrary, for WPIs with intermediate or low α-la content, no changes in physical properties were observed. These results contribute to clarifying the mechanisms underlying the effects of HIU on WPI, linking effects on protein level to physical properties.