Abstract

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 (R) onto polydopamine-coated magnetic nanoparticles (PDA-MNPs) and its application in POS production. Chemical amination of Viscozyme L (R) was evaluated as a strategy to enhance immobilization. Amination increased free amino groups similar to 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 degrees C, pH 4) was evaluated at 167-333 nkat g(-1). After 5 h at 333 nkat g(-1), more than 60% of carbohydrates over 1 kDa were POS (mean Mw approximate to 5.4 kDa) and less than 15% of solids were predominantly monosaccharides. Activity of the immobilized biocatalyst decreased during reuse and stabilized at similar to 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.