Oxidative stability and effect of stress factors on flaxseed oil-in-water emulsions stabilized by sodium caseinate–sodium alginate–chitosan interfacial membrane

The susceptibility of heart healthy ω-3 fatty acids to lipid oxidation has hindered its incorporation into healthful foods and beverages. In this study, plant-based flaxseed oil rich in ω-3 fatty acids were dispersed into primary, secondary and tertiary emulsion system. A primary emulsion containing sodium caseinate-stabilized cationic droplets was prepared by homogenizing flaxseed oil as oil phase and sodium caseinate solution as the aqueous phase in an ultrasonicator. A secondary emulsion comprising of sodium caseinate–sodium alginate anionic droplets were produced by diluting appropriate primary emulsion with alginate solution. Further, a tertiary emulsion composed of sodium caseinate–sodium alginate–chitosan-coated cationic droplets was produced by diluting secondary emulsion with chitosan solution. The resistance of primary, secondary and tertiary emulsions with the same lipid concentration to destabilization by thermal treatment (30–90 °C for 30 min), sodium chloride addition (≤70 mM NaCl) and oxidative degradation (hydroperoxide concentration and TBARS) was determined. The results showed that secondary emulsions could resist variation in environmental stresses of salt and heat as well as protect the oil phase from decomposition better than primary and tertiary emulsions. Interfacial engineering could be used to design emulsion system with desirable characteristics.