Evaluation of physicochemical properties of gluten modified by Glucose oxidase and Xylanase

Abstract

The effect of Glucose oxidase (GOX) and Xylanase (XYL) on gluten-starch separation and physicochemical properties of gluten was studied. The gluten yield and Rmax increased and the extensibility of gluten and the amount of free sulfhydryl groups (SHf) decreased in comparison to the control with the addition of GOX up to 80 ppm. These observations indicated the high strength of gluten network by 80 ppm of enzyme. GOX caused a shift to larger particle size distribution of glutenin macropolymer (GMP) gel. Here, GMP gel at low enzyme level was more elastic and stiffer. Generally, an improvement of GMP gel quality can be obtained by the addition of GOX, although inverse effects were obtained when excessive enzyme levels were added. The results indicated that XYL leads to increase the tendency to aggregate by degradation of pentosane and decreasing the viscosity. The enzyme led to decrease the particle size distribution in GMP gel. In these samples, a tendency to increase the amount of SHf content was observed and it seems that the incorporation of pentosan and protein prevented the disulfide crosslinking. GMP gel separated with XYL had higher delta value and lower storage modulus in comparison to GMP gel separated without XYL.