Impact of antioxidant on the stability of β-carotene in model beverage emulsions: Role of emulsion interfacial membrane

•Structural properties of emulsifier affect β-carotene degradation in emulsions.•Interfacial thickness affect the stability of β-carotene in emulsion droplets.•Interfacial denseness is also important to retard β-carotene degradation.•Effectiveness of lipophilic antioxidant is not affected by interfacial characteristics. The effect of the thickness and density of droplet interfacial membrane on the chemical stability of β-carotene in emulsions was investigated, and its impact on the effectiveness of oil-soluble antioxidants to retard β-carotene degradation was examined. β-Carotene was incorporated into the emulsions stabilized by PEGylated emulsifiers having various-sized hydrophilic groups. In the presence of oxidative stresses (pH, iron ions, and radicals in this study), it was observed that the interfacial thickness was relevant to the stability of β-carotene encapsulated into emulsion droplets. Particularly, iron-mediated carotene degradation was effectively retarded in the emulsions having a thin interfacial membrane than ones with a thick interfacial membrane. The interfacial denseness also affected β-carotene stability but its ability to retard β-carotene degradation was influenced by the interfacial thickness. Although β-carotene degradation rate decreased upon the addition of oil-soluble antioxidants, its antioxidant activity depended on what prooxidant promoted the degradation of β-carotene in the emulsions.