Abstract: One-factor-at-a-time method combined with orthogonal array design was employed to optimize enzymatic extraction of polysaccharides from squid ink with alkaline protease. The antioxidant activity of polysaccharides from squid ink was investigated by DPPH and hydroxyl free radical scavenging assays and ferric reducing assay. The optimal conditions for polysaccharide extraction were 4.5% enzyme amount, 1:15 material-to-liquid ratio, 50 ℃, pH 8 and 4 h, resulting in a polysaccharide yield of 3.63%. Squid ink polysaccharides had some antioxidant activity. A positive liner correlation between the antioxidant activity and concentration of squid ink polysaccharides was found over the investigated ranges. The The half maximal inhibitory concentrations (IC50) against DPPH and hydroxyl free radicals were 3.61 mg/mL and 8.06 mg/mL respectively.

Key words: squid ink, polysaccharides, extract, antioxidant activity