Activity of carbohydrate oxidases as influenced by wheat flour dough components

• We characterised COXMn activity for application as a dough improver.
• The activity of COXMn is compared to that of Aspergillus niger GOX.
• COXMn is more active than GOX in an aqueous wheat flour extract.
• NaCl reduces the activities of COXMn and GOX by 25% and 30% respectively.
• COXMn can be efficient as a dough improver in association with starch degrading enzymes.

The carbohydrate oxidase (COXMn) from Microdochium nivale may well have desired functionalities as a dough and bread improver, similarly to Aspergillus niger glucose oxidase (GOX). COXMn catalyses the oxidation of various monosaccharides as well as maltooligosaccharides for which the best activity is obtained towards the maltooligosaccharides of polymerisation degrees 3 and 4. For the same activity towards glucose under air saturation, we show that COXMn exhibits a similar efficiency towards maltose as GOX towards glucose whatever the oxygen supply. Assays with COXMn show that no competition exists between carbohydrates naturally present in the wheat flour. We show that reaction products (d-glucono-δ-lactone and hydrogen peroxide) and the wheat flour dough component, ferulic acid, have no noticeable specific effect on the COXMn activity. The demonstrated differences in kinetics between COXMn and GOX allow predicting of differences in the functional behaviours of those enzymes during wheat flour dough formation.