Influence of chitosan on the emulsifying properties of egg yolk hydrolysates: study on creaming, thermal and oxidative stability.

Background Egg yolk, as a natural emulsifier, is widely used in high oil phase food system, such as mayonnaise and salad. However, the application of egg yolk in oil-in-water system is still limited due to poor emulsifying stability. To improve the emulsifying capacity of egg yolk, the effect of chitosan addition sequence and concentration on emulsifying properties (creaming stability, thermal tolerance and oxidation resistance) of egg yolk hydrolysates were investigated. Results Stacking sequence of multilayer materials has influence on properties of composite emulsions. The composite emulsions with egg yolk hydrolysis dominate at interface (functioning on reducing interfacial tension) and chitosan layered on the surface (providing steric hindrance) displayed better stability. Little chitosan addition (0.5 g × Kg-1 , w/w) was unhelpful for the dispersion of emulsion droplets as a result of bridging flocculation. At chitosan concentration of 2 g·Kg-1 (w/w), the composite emulsion possesses the best stability. When chitosan concentration was higher than 2 g·Kg-1 (w/w), depletion flocculation would happen. Hydrolyzed egg yolk prepared composite emulsions possessed better thermal resistance while poorer oxidative stability as compared to natural egg yolk. In combination with chitosan also displayed a negative effect on the oxidative stability of emulsion system. Conclusion The research revealed the the effect of chitosan addition on the physical and chemical stability of egg yolk hydrolysates prepared emulsion. The results would provide guidance to expand the application of egg yolk as emulsifier in water abundant food systems like beverage. This article is protected by copyright. All rights reserved.