Use of two endoxylanases with different substrate selectivity for understanding arabinoxylan functionality in wheat flour breadmaking

A Bacillus subtilis endoxylanase (XBS) with a strong selectivity for hydrolysis of water-unextractable arabinoxylan (WU-AX) and an Aspergillus aculeatus endoxylanase (XAA) with a strong selectivity for hydrolysis of water-extractable arabinoxylan (WE-AX) were used in straight-dough breadmaking with two European wheat flours. Dough, fermented dough, and bread characteristics with different levels of enzyme addition were evaluated with a strong emphasis on the arabinoxylan (AX) population. The WU-AX solubilized by XBS during breadmaking were mainly released during mixing and had higher molecular weight, in contrast to their counterparts solubilized by XAA, which were mainly released during fermentation and had lower molecular weight. This coincided with increased loaf volume with XBS and a negative to positive loaf volume response with XAA. Bread firmness and dough extract viscosity also were affected by endoxylanase addition. Results confirmed that WU-AX are detrimental for breadmaking, while WE-AX and solubilized AX with medium to high molecular weight have a positive impact on loaf volume.