Generation of organic acids and monosaccharides by hydrolytic and oxidative transformation of food processing residues.
Carbohydrate-rich biomass residues, i.e. sugar beet molasses, whey powder, wine yeast, potato peel sludge, spent hops, malt dust and apple marc, were tested as starting materials for the generation of marketable chemicals, e.g. aliphatic acids, sugar acids and mono-/disaccharides. Residues were oxidized or hydrolyzed under acidic or alkaline conditions applying conventional laboratory digestion methods and microwave assisted techniques. Yields and compositions of the oxidation products differed according to the oxidizing agent used. Main products of oxidation by 30% HNO(3) were acetic, glucaric, oxalic and glycolic acids. Applying H(2)O(2)/CuO in alkaline solution, the organic acid yields were remarkably lower with formic, acetic and threonic acids as main products. Gluconic acid was formed instead of glucaric acid throughout. Reaction of a 10% H(2)O(2) solution with sugar beet molasses generated formic and lactic acids mainly. Na(2)S(2)O(8) solutions were very inefficient at oxidizing the residues. Glucose, arabinose and galactose were formed during acidic hydrolysis of malt dust and apple marc. The glucose content reached 0.35 g per gram of residue. Important advantages of the microwave application were lower reaction times and reduced reagent demands.
Fischer
Klaus
K
Analytical and Ecological Chemistry Department, FB VI--Geography/Geosciences, University of Trier, Universitätsring 15, D-54286 Trier, Germany. fischerk@uni-trier.de
Bipp
Hans-Peter
HP
D027461:Beta vulgaris; D018533:Biomass; D002264:Carboxylic Acids / Q000737:chemistry* / Q000378:metabolism; D003300:Copper / Q000737:chemistry / Q000378:metabolism; D002523:Edible Grain; D005525:Food-Processing Industry / Q000379:methods*; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000378:metabolism; D006868:Hydrolysis; D027845:Malus; D008872:Microwaves; D008965:Molasses; D009005:Monosaccharides / Q000737:chemistry* / Q000378:metabolism; D017942:Nitric Acid / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction
D002264:Carboxylic Acids; D009005:Monosaccharides; D017942:Nitric Acid; D003300:Copper; D006861:Hydrogen Peroxide; C000520:cuprous oxide