Pectinase Immobilization on a Chitosan-Coated Chitin Support

Pectinase extracted from Aspergillus niger was immobilized on a chitosan-coated chitin support using various methods: immobilization by adsorption (P-QQSA), adsorption on supports activated by 0.5 and 15% glutaraldehyde (w/v) (P-QQSA 0.5 and P-QQSA 15) and covalent attachment to this support using 1% glutaraldehyde (P-QQSA 1). The optimum conditions selected for immobilization were pH 4.5, incubation time of 4h and protein concentration of 340g/mL. Various characteristics of the immobilized pectinase such as optimum pH, heat stability and reusability were evaluated. As a result of immobilization the enzyme's T-50 increased, the best being achieved with immobilization using 15% glutaraldehyde and covalent attachment. The optimum pH of the free and immobilized enzymes were 5 (free), 4.5 (P-QQSA), 4.5-5.0 (P-QQSA 0.5) and 4-5 (P-QSA 1 and P-QQSA 15), respectively. The biocatalysts prepared retained 100% of their original catalytic activity after nine cycles of reuse. Practical ApplicationsPectinases hydrolyze pectin and/or pectic acid. These enzymes have widespread applications in the food industry (processing of fruits), wastewater treatment, textile industries, fruit softening and plant infection processes. The stability of these enzymes depends on the aqueous medium and is easily disrupted to the point where the enzymes cannot function appropriately. Immobilization techniques provide a promising approach to retain their stability. Various methods for immobilization of this enzyme have been described: entrapping in alginate, physical adsorption on anion resin, -alumina, particles and nanoparticles of silica and covalent attachment to carriers such as porous glass and nylon. However, the development of new methods and supports for immobilizing enzymes is of special importance in enzyme technology. The present article describes several methods for immobilization of pectinase in chitosan-coated chitin for use in the juice and wine industries.