Non-isothermal autohydrolysis of barley husks: Product distribution and antioxidant activity of ethyl acetate soluble fractions

Non-isothermal treatments of barley husks in aqueous media were performed under a variety of operational conditions, to cause the hydrolytic degradation of hemicelluloses. The amount and composition of solid and liquid phases were determined. Liquors from treatments were extracted with ethyl acetate in order to remove non-saccharide components (mainly derived from the extractive acid-soluble lignin fractions), and the extracted fractions were quantified and assayed for antioxidant activity using the DPPH radical scavenging test. Posthydrolysis of autohydrolysis liquors led to xylose-containing solutions suitable as fermentation media. The dependence of the major process parameters (concentrations of monosaccharides and monosaccharide-degradation products obtained after autohydrolysis–posthydrolysis, yield of ethyl acetate soluble compounds and antioxidant activity of isolates) on the severity of treatments was assessed. The ethyl acetate soluble fraction obtained under the best processing conditions showed an antioxidant activity in the range reported for synthetic antioxidants.