Valorisation of Potato (Solanum tuberosum) Peel Waste: Extraction of Fibre, Monosaccharides and Uronic Acids

Purpose: The food and starch industries generate large quantities of potato peel waste (PPW) that can be exploited for a range of biotechnological and biofuel applications. The purpose of this study was to characterise the ultrastructure and monosaccharide composition of PPW. Methods: The ultrastructure of PPW was observed using light and immunofluorescence microscopy. Fibre was prepared from PPW using mild detergent and subjected to sequential acid hydrolysis followed by high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). Results: Potato peels are composed of small, stacked cells which generally lack starch granules. These cells are surrounded by thick cell walls rich in pectic polysaccharides. Following sequential extraction, seven different sugars and two uronic acids were identified including (in order of abundance) mannose, galacturonic acid, xylose, glucose, fucose, glucuronic acid, galactose, rhamnose and arabinose. The monosaccharides and uronic acid products showed good stability in the acidic conditions during storage, which would facilitate their downstream purification and eventual commercialisation. Conclusion: PPW is a readily available source of fibre, monosaccharides and uronic acids