MODIFICATION OF SOME PHYSICOCHEMICAL PROPERTIES OF WHEAT-FLOUR PENTOSANS BY AN ENZYME COMPLEX RECOMMENDED FOR BAKING

The effects of a fungal alpha-amylolytic complex containing side activ ities were studied on water-insoluble pentosans (WIP) and water solubl e pentosans (WSP) purified from wheat flour. This enzymatic preparatio n is used in breadmaking for its capacity to improve dough and bread c haracteristics. The enzymatic complex brought about a partial solubili zation of the WIP flour cell-wall fraction, causing up to a 50% weight loss under prolongated exposure. During hydrolysis, 75% of the insolu ble arabinoxylans passed into solution. The insoluble residue, resista nt to the enzymatic degradation, was enriched in glucans. The swelling power of the hydrolyzed residue was double that of the intact WIP, bu t its water-holding capacity remained unchanged. Therefore, the amount of water retained was reduced proportionally compared to the weight l oss of the WIP fraction. On the other hand, the high viscosity of WSP was dramatically decreased by the action of the enzymatic complex. The drop in viscosity during hydrolysis on a mixture of WIP and WSP was l imited by the contribution of the solubilized arabinoxylans. It is app arent from these data that the so-called side activities of the enzyma tic complex were mainly endoxylanase and arabinofuranosidase.