Effect of glucose oxidase and pentosanase on the prebiotic potentials of wheat arabinoxylans in an in vitro fermentation system

Abstract

Arabinoxylans (AXs) treated with enzymes, pentosanase (Pn) and glucose oxidase (GOX) not only offer a promising way to improve wheat product quality but also change their prebiotic potentials by modifying the structures of AXs. In the present study, the different crosslinking degrees of water-extracted arabinoxylans (WEAXs) treated with GOX alone or in combination with Pn + GOX were examined. The structural features and candidate prebiotic capabilities were investigated. It was demonstrated that WEAXs treated with 50 μg g⁻¹ (w/w, enzyme/WEAX) GOX and 200 μg g⁻¹ (w/w, enzyme/WEAX) Pn + 400 μg g⁻¹ (w/w, enzyme/WEAX) GOX exhibited weak gel formation, while WEAXs treated with 400 μg g⁻¹ (w/w, enzyme/WEAX) GOX and 25 μg g⁻¹ (w/w, enzyme/WEAX) Pn + 400 μg g⁻¹ (w/w, enzyme/WEAX) GOX formed strong gels. The ferulic acid content was significantly decreased due to the formation of ferulic acid crosslinking in the enzyme-treated WEAXs (p < 0.05). During in vitro fermentation, GOX and Pn + GOX treatments resulted in significantly (p < 0.05) increased amounts of bifidobacteria compared to WEAX alone. Pn + GOX-treated WEAXs had higher (p < 0.05) bifidobacteria populations than WEAXs treated with GOX alone. The bifidobacteria numbers and the SCFAs content of the weak gels were significantly higher than those in the strong gels under the same enzyme action (p < 0.05). These findings suggested that the increased bifidobacteria populations of GOX-treated WEAXs were due to the formation of ferulic acid crosslinking in contrast to a combination of ferulic acid crosslinking and degradation of the xylan backbone as seen in WEAXs treated with Pn + GOX. The reason the weak gels had better prebiotic potential than the corresponding strong gels was their high content of ferulic acid crosslinking.