An explanation for the combined effect of xylanase–glucose oxidase in dough systems

Abstract

In the bakery industry, glucose oxidase is usually used in combination with xylanase. Although many theories exist on the mechanism of action of each enzyme, the positive effect of combining the two is as yet unexplained. In this paper we studied a possible basis for this synergy by focusing on the involvement of arabinoxylans. Water-extractable arabinoxylans and water-unextractable solids were studied in dough with or without glucose oxidase. Addition of glucose oxidase led to a stiffer and less extensible dough. Addition of arabinoxylans caused a further decrease in dough extensibility. Addition of xylanase could correct for this decrease. The role of arabinoxylans was further investigated by studying modified water-extractable arabinoxylans and the effect of agents affecting arabinoxylan crosslinking (ferulic acid). Water-extractable arabinoxylan was modified with xylanase to generate a low-molecularweight fraction (WEAX XYL ). Alternatively, it was modified with NaOH to prepare a fraction with a decreased ferulic acid content (WEAX OH ). Addition of modified arabinoxylans diminished the effect of glucose oxidase. Glutenin macropolymer and water-extractable arabinoxylan viscosity experiments were performed to obtain further detail on the role of arabinoxylans (AX). These results give rise to a new theory explaining the contribution of xylanase in its synergy with glucose oxidase. In this theory glucose oxidase not only catalyses the formation of protein disulfide bonds, but also of AX-AX crosslinks. The latter negatively affect bread quality. Xylanase corrects for this latter effect by cleaving arabinoxylan complexes and generating small ferulic acid-containing arabinoxylan fragments interfering with the crosslinking of high-molecular weight arabinoxylans.

Research into the impact of enzyme preparations on the processes of grain dough fermentation and bread quality

“…Less significant hydrolysis of cellulose, compared to hemicelluloses, can be associated with low compliance of cellulose to the action of enzymes, which is consistent with the data given in [29]. It is known that during hydrolysis of nonstarch polysaccharides under the influence of xylanase and cellulose, the compounds with high water-absorbing capacity are formed, which increase the viscosity of dough, which provides improving effect from the application of enzyme preparations [18].…”

“…To get an idea about the effect of xylanase, cellulase and glucose oxidase on the regularities of formation of properties of grain dough, we thought it appropriate to investigate in dynamics the changes in the content of fiber, hemicelluloses, including soluble and insoluble, that are able to bind substantial amounts of moisture in the system and affect the rheological properties of the dough [18]. Results of the study are presented in Fig.…”

“…In the scientific literature there are data available on the beneficial effect of the products of hydrolysis of hemicelluloses on the properties of gluten, which can form protein-polysaccharide complexes, promoting the improvement of rheological properties of gluten and dough [18]. At the same time, as a result of the destruction of the protein-polysaccharide bonds in grain under the influence of cellulolases and hemicellulases, the availability of gluten-forming proteins that form the structure of the dough may increase [18], which contributes to the improvement of rheological properties of dough.…”

“…Among the enzymes of this group, the most promising includes glucose oxidase, under the influence of which oxidation of glucose occurs with the formation of hydrogen peroxide and its further inclusion in the processes of oxidation of thiol groups of protein protease complex, which allows using this enzyme during the processing of flour with weak gluten [17]. In addition, many modern studies [18][19][20] discuss the feasibility of joint application of enzyme preparations of xylanase and glucose oxidase due to the synergy of their actions.…”

Surface Layer Properties of Dough Liquor Components: Are They Key Parameters in Gas Retention in Bread Dough?

“…This could be explained by the (small) change in surface properties and/or by a large reported effect of arabinoxylans on the bulk rheological properties of the dough. [21][22][23][24] Which of these effects is the most important remains to be unraveled.…”