Impact of chitosan–EGCG conjugates on physicochemical stability of β-carotene emulsion

The aim of the present study was to investigate the effects of low-molecular-weight chitosan (LC)–(−)-epigallocatechin-3-gallate (EGCG) conjugates on the physicochemical properties of oil-in-water emulsions incorporating β-carotene within the oil droplets. Covalent coupling of LC to EGCG was achieved by hydroxyl-free radical grafting. The physicochemical stability of β-carotene emulsions was characterized by droplet size and distribution, rheological behavior, transmission profiles using novel centrifugal sedimentation and β-carotene degradation in the emulsion during storage. β-Carotene emulsions stabilized by LC–EGCG conjugates had relatively smaller mean droplet size, more homogenous droplet size distribution and less change in centrifugal transmission profiles, indicating a substantial improvement in physical stability. Degradation of β-carotene in emulsions during storage was significantly retarded by LC–EGCG conjugates than native LC (formed without the redox pair and without EGCG) and control LC (formed with redox pair and without EGCG). These results implied that LC–EGCG conjugates were able to improve the physical stability of β-carotene emulsion and inhibit the deterioration of β-carotene in oil-in-water emulsions.