Immobilization of Pectinase onto Polydopamine-Coated Magnetic Nanoparticles for Pectic-Oligosaccharide Production

Pectic-oligosaccharides (POS), produced by the enzymatic hydrolysis of pectin, have bioactive properties, including antimicrobial and antioxidant effects. In this study, we evaluated the immobilization of the commercial multienzyme preparation Viscozyme L® onto polydopamine-coated magnetic nanoparticles (PDA-MNPs) and its application in POS production. Chemical amination of Viscozyme L® was evaluated as a strategy to enhance immobilization. Amination increased free amino groups ∼4-fold, enabling a 5-fold increase in immobilized protein and an 8-fold increase in expressed activity (428.2 nkat g -1 ). Immobilization of aminated pectinase preserved the soluble aminated pH/temperature profile. Production of POS from apple pectin (50 °C, pH 4) was evaluated at 167–333 nkat g -1 . After 5 hours at 333 nkat g -1 , more than 60% of carbohydrates over 1 kDa were POS (mean Mw ≈ 5.4 kDa) and less than 15% of solids were predominantly monosaccharides. Activity of the immobilized biocatalyst decreased during reuse and stabilized at ∼30% from cycles 4 to 6. Hydrolysates partially inhibited Escherichia coli and Salmonella , and antioxidant activity (DPPH) was more than 4-fold higher than native pectin. These findings highlight enzyme amination as a general strategy to enhance immobilization efficiency onto PDA supports and demonstrate its potential for producing bioactive POS for food applications. • Pectinase was immobilized for the first time on PDA-coated magnetic nanoparticles • Enzyme amination increased activity of immobilized catalyst up to 8-fold • The enzyme stability was improved due to amination and immobilization • Pectin hydrolysis time tunes composition and bioactivity of product