Effect of pullulan hydrolysates on the quality of Nile tilapia ( Oreochromis niloticus ) fillets during ice storage

Abstract

Pullulan was hydrolyzed by pullulanase producted by Bacillus megaterium. The ABTS+, OH, and DPPH scavenging activities of hydrolysates were 37.73, 21.67, and 17.03%, respectively, when its concentration reached 30 mg/ml, significantly higher than pullulan (p < 0.05). Edible coatings based on pullulan hydrolysates were used to preserve Nile tilapia (Oreochromis niloticus) fillets under ice storage. The results showed that 2 and 3% hydrolysates were most effective in decreasing physicochemical changes including 2-thiobarbituric acid (TBA), total volatile basic nitrogen, electrical conductivity, pH, water loss, and discoloration, inhibiting bacterial growth; and increasing the sensory quality of fish fillets compared with control samples (p < 0.05), and no significant differences were observed between them (p > 0.05). Practical applications Edible coating based on polysaccharide is an ideal method of fish fillets preservation. Results indicated that pullulan hydrolysates has good ability on extending shelf life of fish fillets. This study could provide a efficient method on the quality control of Nile tilapia fillets.