Influence of pH, metal chelator, free radical scavenger and interfacial characteristics on the oxidative stability of β-carotene in conjugated whey protein–pectin stabilised emulsion

The influence of whey protein isolate (WPI)–beet pectin conjugates formed by dry-heating on the oxidative stability of β-carotene in O/W emulsions was studied. It was mainly focused on the influence of pH, metal chelator, free radical scavenger and interfacial characteristics on the degradation of β-carotene in the emulsion stabilised by conjugate. The conjugate increased the oxidative stability of β-carotene in the emulsion as compared to their unconjugated mixture at pH 7.0. The desferoxamine retarded β-carotene degradation at pH 4.0 more effectively than pH 7.0 and more effectively in the emulsion with the conjugate than the unconjugated mixture (p < 0.05). The addition of 200 mg/kg α-tocopherol significantly improved the stability of β-carotene in the conjugate stabilised emulsion. The emulsions were washed to remove conjugate not absorbed to the emulsion droplet interface, indicating that unabsorbed emulsifiers could protect β-carotene. It suggested that WPI–pectin conjugate could be used to protect bioactive lipids in emulsions.