Stabilization of O/W emulsions via interfacial protein concentrating induced by thermodynamic incompatibility between sarcoplasmic proteins and xanthan gum

Abstract

Thermodynamic incompatibility between sarcoplasmic proteins (SPs) and xanthan gum (XG) in aqueous solutions and enhanced emulsion stabilization induced by interfacial concentrating were discovered in this research. The phase diagram was investigated in the dependence of the concentrations of SP and XG at pH 7.2. With XG fixed at 0.5%, as the SP concentration in the solution system was increased, the mean particle size of the aqueous system decreased gradually. This might be attributed to the reduction in the aggregation of XG. The Turbiscan Stability Index and delta backscattering profiles indicted that 1% was the critical SP concentration, thermodynamic incompatibility then enhanced greatly and led to phase separation once exceeding 1%. Particle size distribution results and confocal laser scanning microscopy images revealed that in the emulsion system, the particle size distribution of the droplets and flocculation decreased as the SP concentration reached 2% (w/v). The results of interfacial properties suggested that due to the interfacial concentrating effect by XG, more SPs are adsorbed onto the oil-water interface, resulting in an increase in interfacial pressure. The decrement in ζ-potential in the presence of XG (from −23.42 mV to −21.80 mV at 2% SPs) implied that the charge stabilization effect did not dominate in the stabilization of SP/XG-based emulsions. The emulsion with 0.5% XG showed better physical stability. Our research may have potential implications for the recycle of SPs and the regulation of meat-protein-based emulsions by the interfacial concentrating effect.