Oxidative aging of plant protein-stabilized emulsions and its impact on carotenoid bioaccessibility.

Plant proteins are widely used as natural emulsifiers for carotenoid-enriched foods, yet most delivery studies evaluate freshly prepared emulsions instead of products stored before consumption. During storage, lipids, interfacial proteins, and carotenoids undergo concurrent oxidation. Lipid hydroperoxides and secondary products can modify adsorbed proteins, while carotenoids are prone to isomerization, epoxidation, and oxidative cleavage. Accordingly, the interfacial layer encountered during digestion may differ markedly from that formed after homogenization. This difference can affect pepsin hydrolysis, bile salt displacement, lipase adsorption, lipid digestion, and carotenoid micellization. This review introduces oxidative aging as a concept for describing progressive chemical and structural changes in plant protein-stabilized oil-in-water emulsions during storage. It examines protein sources, residual non-protein components, degree-dependent protein oxidation, and their links to carotenoid bioaccessibility. Limitations of current storage and digestion studies are discussed, and a storage-to-digestion strategy is proposed to improve carotenoid protection during shelf life while maintaining gastrointestinal release.