Enzymatic Modification of Ferulic Acid Content in Arabinoxylans from Maize Distillers Grains: Effect on Gels Rheology

Maize distillers grain (MDG) is a by-product of distillery plants produced in large amounts worldwide. MDG is used in livestock feed, however, it is rich in arabinoxylans (AX) which could add value and favor the sustainable development of distillery plants. The aim of this work was to modify the ferulic acid (FA) content in AX from MDG by using a ferulate esterase and to investigate the rheological characteristics of the gels formed. FA content in AX and ferulate esterase treated AX (FAX) was 5.0 and 3.7 µg/mg polysaccharide, respectively. AX and FAX formed gels at 2% (w/v) with elasticity (G′) and viscosity (G′′) values of 195 and 112 Pa and 0.7 and 0.5 Pa, respectively. The gelation time was lower in AX (13 min) than in FAX (16 min). The mechanical spectrum of AX and FAX gels exhibited G′ higher than G′′ and G′ independent of frequency whereas G′′ was dependent on frequency. These results confirm the importance of FA content in the rheological characteristics of the AX-based gels. Enzymatic modification of FA content in AX from MDG could offer an interesting opportunity for the reliable design of tailored gels which could add value to this maize by-product.