Pectic oligosaccharides production from orange peel waste by enzymatic hydrolysis

Summary Orange peel waste (OPW) was evaluated as a raw material for the enzymatic production of pectic oligosaccharides. In a preliminary step, free sugars and other water‐soluble compounds were extracted from OPW to obtain a substrate for enzymatic hydrolysis (EHS), to achieve two objectives: (i) removal of sugars and impurities, and (ii) production of a sugar‐rich stream suitable for further utilisation, according to the ‘biorefinery’ philosophy. EHS was treated with hydrolytic enzymes (pectinases and cellulases), and the effects of selected operational variables (enzyme charges and reaction time) on selected dependent variables (measuring the conversions of polysaccharides into mono‐ and oligosaccharides, and liquor recovery) were assessed. Mathematical models were developed for this purpose. Under selected conditions, the models predicted that 100 kg of EHS yielded 7.5 kg of gluco‐oligosaccharides, 4.5 kg of galacto‐oligosaccharides, 6.3 kg of arabino‐oligosaccharides and 13 kg of oligogalacturonides (contained in 991.6 kg of liquor).