Lycopene-loaded bilayer emulsions stabilized by whey protein isolate and chitosan

In this study, bilayer emulsion loading lycopene was prepared using lycopene oil solution (0.8 wt%) as oil phase, whey protein isolate (WPI) solution (0.6 wt%) as the first layer and the chitosan solutions (0–1.50 wt%) as the second layer. The effect of chitosan concentration on droplet size, zeta (ζ)-potential and physical stability of the bilayer emulsion was evaluated and the bilayer emulsion stabilized by chitosan solution of 0.5 wt% concentration showed the best physical stability. In addition, the effects of environmental stress, pH and ionic strength on the bilayer emulsion were measured and the result proved that the bilayer emulsion could provide a better protection for lycopene encapsulated than the WPI monolayer emulsion. Besides, different antioxidants (oil-soluble: oil-soluble tea polyphenol, ascorbyl palmitate and vitamin E; hydrosoluble: bamboo leaf flavonoid, D-sodium erythorbate and vitamin C) were added into the oil phase, the first layer and the second layer of the lycopene bilayer emulsions, respectively. The physical characteristics, storage stability and light stability of the bilayer emulsion were then evaluated to determine the effects of antioxidants in different locations on the emulsion.