Effect of the immobilization of pectinase on the molecular weight distribution of pectin oligosaccharides obtained from citrus pectin

Abstract

Current sustainability guidelines require industrial byproducts to be returned to the production cycle. One of the most important byproducts for agriculture and food production is pectin, which can be hydrolyzed to obtain pectin oligosaccharides (POS), with potential use as prebiotics. One of the challenges in POS production is the modulation of their molecular weight since those between 1 and 3 kDa exhibit higher prebiotic activity. In this work, a pectinase preparation was used for pectin hydrolysis, evaluating the effect of enzyme immobilization on the molecular weight distribution of the obtained POS. The pectinase preparation immobilized on functionalized silica with amino and glyoxyl groups and expressed 88.6 U per g of support. Enzyme immobilization improves thermal resistance at 50 °C and pH 4.0 compared to soluble pectinase. Immobilization also influences pectin hydrolysis and thus the POS generation, increasing yield by 10% when the immobilized pectinase was used. Interestingly, pectinase immobilization resulted in an average of 2.5 kDa for obtained POS.In contrast, soluble pectinase resulted in a continuous decrease of POS molecular weight over hydrolysis time. This difference could be attributed to the enzyme confinement on the porous silica, limiting the reduction in molecular weight of POS, probably because the immobilized enzyme exhibits higher diffusional restrictions than free enzymes. Our results help to understand and design an efficient and sustainable process to produce tailored prebiotic molecules from agro-industrial byproducts.