Fundamental understanding of the role of gelatin in stabilizing milk protein systems during acidification.

The effect of two types of gelatin (A &B) on the stability of the dispersions with 1% milk proteins during acidification was studied. A dramatically different effect was observed with gelatin concentration from 0.1% to 1%. Gelatin B showed no significant effect on the zeta potential of the dispersions, while gelatin A changed the zeta potential from negative to positive with an increase in concentration. From the microrheology results, gelatin B showed little effect on elasticity index (EI), except that the samples containing higher concentrations led to slight decrease in EI values due to the steric inference. Conversely, gelatin A showed greater influence on EI, and the effect was more significant at low concentrations than high concentrations. Both static and dynamic light scattering (SLS & DLS) showed that low concentrations of gelatin A induced faster aggregation of milk proteins, while both types of gelatin showed stabilizing effect at high concentrations. CD spectra indicated that the gelatin/casein interaction could be the major attribute for the different effects of two types of gelatin on milk proteins. • Low concentrations of gelatin A promoted milk protein aggregation. • Gelatin A stabilized the milk protein solutions via electronic interactions. • Gelatin B stabilized the milk protein solutions via steric interference. • CD spectra showed differences in gelatin A/B interacting with casein. [ABSTRACT FROM AUTHOR]