The Influence of Crushing of Wheat Bran on the Properties and Reactivity to Biocatalytic Conversion

Abstract

Potentialities of wheat bran as a feedstock for biocatalytic conversion to synthesize sugars were demonstrated. The relatively low reactivity of the feedstock can be 2–4 fold increased through its dry crushing using a planetary mill-activator. A complex enzymatic agent (EA) Penicillium verruculosum gaBG showing cellulolytic, hemicellulolytic and amylolytic activity was used to improve the yield of reducing sugars; the maximal yield equal to 68,8 mg/L at the initial substrate concentration of 100 g/L in the reaction mixture was reached through biocatalytic conversion of wheat bran milled for 7–10 min in the presence of 60 mg/g of EA gaBG (and additional EA β-glucosidase F10, 40 unit/g), glucose being predominant among the produced sugars (93–95 %). The content of polysaccharide components was 62,4 % of the dry basis of wheat bran; hence, the observed sugar yield was close to the theoretical yield (with regard to water added during the enzymatic hydrolysis), and the carbohydrate component of the broken wheat bran was practically completely converted. Lengthening of the crushing time to 7–10 min resulted in a considerable decrease in the bran particle size, in weakening of their ability to bind water (by 28 %), in doubling of the content of soluble sugars and in an increase (by 12,6 %) in the total content of soluble components against those in the initial feedstock.