Bioconversion of orange peel into prebiotic pectic oligosaccharides via integrated immobilized polygalacturonase hydrolysis and probiotic fermentation

Pectic oligosaccharides (POS) produced using a combined approach: enzymatic hydrolysis by endo-polygalacturonase (PGC-AN64) and probiotic fermentation using Lactiplantibacillus plantarum S72. They were characterized for monosaccharide and oligosaccharide composition (HPAEC-RI), structural features (ATR-FTIR and XRD), viscosity, pH, and prebiotic potential. Enzymatic hydrolysis reduced viscosity and crystallinity while increasing soluble sugars and galacturonic acid content. Combined enzymatic and fermentation treatments yielded higher amounts of oligogalacturonic acids, and fermentation enhanced lactic acid formation. In vitro evaluation using L. plantarum S72 demonstrated that POS, particularly from enzymatic or combined treatments, promoted probiotic growth and acidity, which were comparable to or superior to those of commercial inulin. These findings indicate that integrating immobilized PGC-AN64 hydrolysis with probiotic fermentation is an effective and sustainable strategy to convert orange peel into functional pectic oligosaccharides for potential food applications.