Extraction of Carbohydrates and Phenolics from Barley Hull using Pressurized/Subcritical Fluids

Abstract

Canada is one of the largest barley producers, generating barley hull which accounts for 10-13% wt of the grain. Barley hull has valuable components, such as carbohydrates and phenolics. This thesis studied the extraction of total carbohydrates and phenolics from the hull of a new barley variety (BT 584) using solid-liquid batch (SLB), subcritical fluid (sCF) and supercritical CO2 (SC-CO2) extraction methods. The optimization of the variables was performed using response surface methodology (RSM) with a central composite design. The sCF extraction was the most effective method, yielding 122.4 mg of total phenolics/g of barley hull and 589.4 mg of total carbohydrates/g of barley hull at 240°C, 15MPa, with 12% ethanol concentration, flowing at 5 mL/min. A kinetic model was used to fit the curves of the sCF extraction with mean square error lower than 0.06.