Pretreatment of various feedstocks for lactic acid production: detection of sugars, organic acids and furanics in liquid fractions

Barley straw, sugarcane bagasse and empty fruit bunches were pretreated under acid- and alkaline conditions. Solid phase was separated from the liquid phase and the concentration of dissolved monomeric sugars, organic acids and furanics was determined. Acid hydrolysis yielded monomeric xylose concentrations (max 20 g/l) whereas for alkaline hydrolysis less than 1 g/l was found. Organic acids and furanics were detected with high concentrations when dried empty fruit bunches were used. Acetic acid was found in all samples (max 3 g/l), concentrations were higher under alkaline conditions.