Preparation of alginate core-shell beads with different M/G ratios to improve the stability of fish oil

•Alginates with different M/G ratios can encapsulate fish oil in core-shell beads by co-extrusion.•A low G content (70.4%) alginate contributed to the better stability of core-shell beads.•Oxidative stability of the fish oil decreases in the order of core-shell beads > free oil > emulsion.

Feasibility of encapsulating fish oil in core-shell beads using alginates with different M/G ratios was investigated for improving the stability of fish oil in an acidic solution and the effect of alginate properties on the stabilization of fish oil core-shell beads. Core-shell beads were placed into buffer solutions with different pH values. At equivalent alginate concentrations, the beads exhibited marginal shrinkage in an acidic solution. At pH 9-11, the beads were swollen. At all pH values, the amount of leaked oil increased with decreasing alginate concentration. All three types of alginates with different M/G ratios (70.4%; 79.4%; 88.0%) can encapsulate fish oil in core-shell beads. The results obtained from the stability treatment of three core-shell beads containing different α-l-guluronic acid contents indicated that the wall materials of beads with low G content were viscous. Therefore, it (G = 70.4%) can be a suitable material for improving the oxidation stability of fish oil in an acidic medium. Based on the obtained peroxide and p-anisidine values, it can be suggested that core-shell beads are beneficial for improving the oxidative stability and retention rate of polyunsaturated fatty acids in an acidic solution.