Physical and oxidative stability of n‐3 delivery emulsions added seaweed‐based polysaccharide extracts from Nordic brown algae Saccharina latissima

Enriching foods with long-chain n-3 polyunsaturated fatty acids requires a delivery emulsion system, which is both thermodynamically and oxidatively stable. The antioxidant and stabilizing properties of three types of polysaccharide extracts from brown algae Saccharina latissima with a mixed composition of polysaccharides (SA: 98% sodium alginate, SF: 90% alginate and 9% fucoidan, SL: 14.5% fucoidan, 9.5% laminarin, and co-extracted nonpolysaccharides) were evaluated. SA, SF, SL, and REF (added commercial sodium alginate) showed in vitro ferrous ion chelating ability in the order: SA (99%) > SL (78%) > REF (31%) > SF (16%). The difference in antioxidant activity between SA, REF, and SF appeared related to structural differences of alginate (M/G ratio). A storage trial was conducted using 70% (w/w) fish oil-in-water delivery emulsions added sodium caseinate (NaCas) (0.23 wt%) as emulsifier in combination with SA, SF, SL, or commercial NaAlg (REF) in different concentrations (C1 = 0.1, C2 = 0.2, C3 = 0.3, and C4 = 0.4 wt%). A control with only NaCas was included (CON). The physical (e.g., creaming and droplet-size distribution) and oxidative (peroxide value and volatiles) stability of the emulsions, were evaluated (12 days, dark at 20˚C). Acceptable physical stability (creaming index) was found for REF (all concentrations), SF = 0.2 wt% (C2), SL and SA = 0.3 wt% (C3) and 0.4 wt% (C4). In general, the oxidative stability decreased by adding REF, SA, and SF (except for REF at C1), as prooxidant activity was observed. However, SA showed antioxidant activity against the formation of 2-ethylfuran. SL showed antioxidant activity in decreasing the formation of volatile compounds in emulsions when added in concentrations above 0.2 wt%.