Foaming properties of milk protein dispersions at different protein content and casein to whey protein ratios

Foaming properties, including foamability, foam stability and foam structure, of milk protein dispersions at different protein content and casein (C) to whey protein (WP) ratios were investigated. Increasing the protein content from 1.5 to 4.0% (w/w) significantly increased the foam stability of milk protein dis-persions. Meanwhile, lowering the C:WP ratio from 80:20 to 40:60 led to a substantial decrease in the foam stability of milk protein dispersions. High viscosity of the high protein content samples was pri-marily responsible for the observed increase in their foam stability, while the increase in the foam stability of high C:WP ratio samples was possibly due to the adsorption and spreading of the micellar caseins at the air-liquid interface compared with the whey proteins. Regarding foam structure, samples with either the higher protein content or the higher casein ratio showed a smaller average air bubble size. (C) 2020 Elsevier Ltd. All rights reserved.