Investigations into the Effects of an Enzyme Preparation for Baking on Wheat Flour Dough Pentosans

Abstract

The modification of pentosans in doughs by a fungal enzyme preparation, used as flour improver, is reported. In the absence of added enzyme, 15-20% of water-unextractable anhydro-arabinose plus anhydro-xylose (ara + xyl) were solubilized during dough processing, depending on the starting flour used. At the optimal dosage for best technological effects, the enzyme preparation brought about a further (ara + xyl) solubilization of 9-29%. This liberation of arabinoxylans modified the viscosity of water extracts from the doughs. The specific viscosities of extracts from enzyme-treated doughs were much enhanced (≈ 40-65%), as compared to the control, because the average apparent intrinsic viscosity of extracted arabinoxylans (both water-extractable and enzyme-released) remained high. The effect of a pure endo-xylanase, isolated from this enzyme preparation, was essentially the same as the crude preparation on dough pentosans. Some hypotheses about mechanisms by which a depolymerizing enzyme can release high Mr arabinoxylans and increase the viscosity were investigated: an alkaline treatment, intended to split ester bonds, did not reduce the viscosity significantly; on the other hand, when a flour from which the water-extractable material had been removed was used as starting material, the intrinsic viscosity of enzyme-released arabinoxylans was much lower. The improving action of the enzyme preparation on doughs may be partly attributed to solubilized arabinoxylans.