Pectic Polysaccharides Recovery from Rapeseed Meal via Conventional and Enzyme-Assisted Extraction Techniques: Toward Emerging Prebiotic Pectic Oligosaccharide Development

This study investigates the extraction of pectic polysaccharides from rapeseed meal (RSM) using both conventional and enzyme-assisted techniques, and the obtained pectic polysaccharide fractions will be used later to produce prebiotic pectic oligosaccharides (POS). A two-step process was developed, involving enzymatic treatment with Alcalase® 2.4 L for 2 h and Cellic® CTec3 HS preparations for 24 h, followed by ammonium oxalate extraction, which effectively isolated two pectic polysaccharide-enriched fractions: PP-EAE (first step) and the resulting Ca-bound pectic polysaccharides fraction (CaPP-EAE) (second step). Both fractions exhibited a bimodal molecular weight profile, indicative of the presence of long-chain polysaccharides alongside oligosaccharides. CaPP-EAE compositional analysis revealed that the fraction contained 56.8% galacturonic acid (GalA), low methyl-esterified (LM) pectins with 53.2% homogalacturonan (HG) and 30.2% rhamnogalacturonan I (RG-I) domains, featuring side chains of arabinan, arabinogalactan, and galactan. Subsequent enzymatic treatment with 0.5% (v/v) of Pectinex® Ultra Passover for 30 min transformed these fragments into a mixture of short-chain POS. Importantly, the produced short-chain POS fraction demonstrated enhanced prebiotic activity, particularly for bacterial strains of the family Lactobacillaceae, compared to a yeast strain. These findings provide a sustainable, biorefinery-compatible approach for extracting and modifying RSM polysaccharides, supporting the development of structurally defined POS as novel prebiotics.