Effect of the mass ratio of heat-treated whey protein isolate to anthocyanin on its composite properties

Abstract The physical and chemical properties of whey protein isolate (WPI)-anthocyanin (AN) complexes formed at different WPI:AN mass ratios and with heat treated WPI [WPI(H)] were investigated. As AN mass ratio increased, the average particle size of the WPI-AN complex decreased from 92.83 nm to 64.20 nm. When the WPI(H):AN mass ratio was 20:1, the absolute value of the zeta potential of the WPI-AN complex reached its maximum. At this time, the complex solution was most stable from the comprehensive view of its particle size, potential and binding amount. Turbidity of WPI-AN complex increased with increased AN mass ratio. Foam stability of the WPI(H)-AN complex solution was 2.72 times that of a WPI solution. After WPI was cross-linked with AN, the surface hydrophobicity decreased significantly with an increase of AN concentration. Fluorescence spectrum and infrared spectrum showed that addition of AN changed the structure of the WPI.