Dynamic monitoring of the protein-lipid co-oxidation of algae oil-enriched emulsions coated with soybean protein-rutin covalent conjugates

Abstract

The stabilities and levels of protein-lipid co-oxidation of algae oil-in water (O/W) emulsions coated with the soybean protein 7S/11S or their rutin covalent conjugates were studied during storage. After 96 h of storage, the emulsions stabilized with the covalent conjugates exhibited decreased droplets sizes and ζ-potentials and increased concentrations of adsorbed proteins. Therefore, the covalent binding of rutin in different mixing ratios (at 7S/11S:rutin molar ratios of 1:10 and 1:20) improved the physical stabilities of the emulsions compared with those of the emulsions stabilized by native 7S/11S. The 7S/11S-rutin covalent conjugates, which formed interfacial barriers and exhibited good free radical scavenging properties, inhibited protein oxidation (with lower contents of protein carbonyls, N'-formyl-L-kynurenine, and Schiff bases, and decreased intensities of intrinsic tryptophan fluorescence) and lipid oxidation (with lower contents of lipid hydroperoxide and malondialdehyde) as storage time increased. The electronic nose test distinguished the flavor characteristics of the emulsions coated with different protein-based stabilizers. These results reveal the viability of utilizing soybean protein-rutin conjugates in protein-stabilized algae oil-fortified emulsions with enhanced storability.

Keywords: Adsorbed proteins; Flavonoid; Polyunsaturated fatty acid; Protein-lipid co-oxidation; Soybean protein.