Exceptional heat stability of high protein content dispersions containing whey protein particles

Due to aggregation and/or gelation during thermal treatment, the amount of whey proteins that can be used in the formulation of high protein foods e.g. protein drinks, is limited. The aim of this study was to replace whey proteins with whey protein particles to increase the total protein content and heat stability. For this purpose whey protein particles with a size of a few micrometers were formed through emulsification and heat gelation of a 25% (w/w) whey protein isolate (WPI) solution at either pH 5.5 or at pH 6.8. Dispersion of whey protein particles formed at pH 5.5 showed an exceptional heat stability (at pH ~ 7); the viscosity of the dispersions containing a total protein concentration around 18% (w/w) did not change after heating at 90 °C for 30 min, while a WPI solution already gelled under same heating conditions at protein concentrations around 11% (w/w). Additionally, no gelation was observed in the dispersions prepared by pH 5.5 particles, when the total protein concentration was increased above 20% (w/w). However, due to the increased particle concentration shear-thickening was observed in these samples. Whey protein particles prepared at pH 6.8 showed rather weak stability against heat treatment, mainly as a result of swelling. Protein particles were not resistant to gastric digestion and complete degradation of the particles was observed after a short incubation time under pancreatic conditions. In conclusion, the use of dense whey protein particles has been shown to be a useful strategy to counter aggregation and/or gelation problems in high protein foods