Abstract:[Objective]This study aims to construct chitosan and chitin-based carriers with hierarchical porous lamellar structures, systematically evaluate the immobilization effects of these carriers for Pseudomonas fluorescens lipase (PFL) and the performance of the immobilized enzyme in catalyzing the hydrolysis of fish oil.[Method]Chitin/chitosan were modified via the sol-gel method to prepare the carriers for the binding with free PFL. The enzymatic properties of the immobilized PFL were then evaluated, and then analysed the hydrolysate composition of anchovy oil catalyzed by the immobilized PFL.[Result]The modified carriers exhibited lamellar structures with abundant free amino groups on the surface, which facilitated covalent immobilization of the enzyme. The chitosan-based carrier achieved the immobilization efficiency of 89.26%, the enzyme loading of 2.21 g/mg, and the PFL enzyme activity of 221.33 U/mg (2.54 folds that of the free enzyme). The chitin-based carrier showed the immobilization efficiency of 71.62%, the enzyme loading of 1.84 g/mg, and the PFL enzyme activity of 185.34 U/mg (2.12 folds that of the free enzyme). The chitosan and chitin-immobilized PFL exhibited optimal catalytic activity at 55 ℃ and pH 8.0, along with significant tolerance to organic solvents such as methanol, ethanol, and glycerol and storage stability. After 11 days of storage at 4 ℃, the enzyme activity reached 115.11 U/mg and 91.43 U/mg, respectively. In the hydrolysis of anchovy oil, the hydrolysis degrees of the chitosan and chitin-immobilized PFL were 23.1% and 19.7%, respectively. The proportions of EPA and DHA in the chitosan-immobilized PFL increased to 25.34% and 18.51%, respectively, while the proportions of EPA and DHA in the chitin-immobilized PFL increased to 25.96% and 18.89%, respectively.[Conclusion]This study demonstrates the potential of hierarchical chitosan and chitin-based carriers in enhancing the catalytic performance of lipase and provides a theoretical basis and practical support for the development of immobilized enzymatic systems for the efficient enrichment of ω-3 fatty acids from deep-sea fish oils.
