Whippable emulsions co-stabilized by protein particles and emulsifiers: The effect of emulsifier type

Advancing an in-depth understanding of the stabilization mechanism of the whippable emulsions co-stabilized by protein colloidal particles and emulsifiers is necessary for the construction and modulation of emulsions suitable for a wider range of foods. In this study, four typical nonionic (GMS: glycerol monostearate, GML: glycerol monolaurate, Tween 60) or ionic (SSL: sodium stearoyl lactylate) small molecular weight emulsifiers (LMWEs) with partially different molecular structures were selected to fabricate low-saturated oil-in-water emulsions and emulsion foams together with zein colloidal particles (ZCPs), respectively. Particle size distribution, overrun, and creaming index were used to evaluate the stability and foaming ability of the whipping or whipped emulsions. In addition, percentage of adsorbed protein, zeta potential, and FT-IR were employed to investigate the effect of LMWEs on the stability of ZCPs at the oil-water or air-water interfaces, and the interaction between these two substances at the interfacial or molecular level. The results show that before aeration, all LMWEs can effectively assist ZCPs to stabilize emulsions and promote interfacial adsorption of ZCPs; however, only the emulsions containing nonionic emulsifiers can be further developed to the foams with higher overrun. Tween diminished the stability of whipped emulsions and the amount of ZCPs assembled at the interface. The interfacial stability of ZCPs is closely related to the length of the hydrophobic chain of LMWEs, as well as the size and polarity of hydrophilic heads, whereby possible mechanisms for the influence of different types of LMWEs on both interfaces in emulsions and foams are proposed.