Effect of flour water-extractable pentosans on molecular associations in gluten during mixing

Abstract

Wheat gluten and mixtures of gluten and water-extractable pentosans (WEP) were mixed in a counter-rotating batch mixer at constant hydration level, in order to study the effects of feruloylated arabinoxylans (AX) on gluten mixing properties. The presence of WEP delayed the development time of gluten, suggesting a competition for water during the first stage of dough formation. Changes in macromolecular associations were followed using size-exclusion high-pressure liquid chromatography (SE-HPLC). SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and solubility measurements. WEP did not affect the breakdown rate of proteins during mixing, when compared on specific energy mechanical basis. Mixing did not affect AX solubility and viscosity. Nevertheless, ferulic acid (FA) content decreased during mixing. This decrease involved mostly FA esters of compounds soluble in acetone/methanol/water (7/7/6, v/v/v) which are present in gluten. These soluble FA esters are likely to react with proteins during mixing. They would be involved, rather than feruloylated AX, in gluten breakdown during overmixing, since no covalent complex between AX and protein was detected in overmixed doughs. © 2002 Elsevier Science Ltd. All rights reserved.