Application of alginate oligosaccharide produced by enzymatic hydrolysis in the preservation of prawns

Alginate oligosaccharide (AOS) was enzymatically prepared and had a degree of polymerization (DP) of 2–6. AOS exhibited evident antioxidant efficacy in ABTS+ scavenging activity, hydroxyl radical scavenging capacity, and total reducing power. The freshness of the prawns, which were treated with AOS and ε-polylysine (ε-PL), was evaluated by measuring indicators such as total viable bacteria (TVC), pH, total volatile basic nitrogen (TVB-N), sensory, texture, and melanosis during storage period. The texture properties and sensory scores of prawns treated with AOS and ε-PL were significantly improved (P < 0.05) in comparison with the control group. Meanwhile, the increase in TVC, pH, TVB-N, and melanosis scores of prawns treated with AOS and ε-PL were effectively delayed (P < 0.05) in comparison with control group. Moreover, the quality of prawns treated with 8 g/L AOS was better than that of prawns treated with 6 g/L. AOS could prolong the shelf life of prawns by 2 days at least. Therefore, AOS is a natural biological preservative in providing an effective and safe way to preserve freshness of prawns.