The influence of varying levels of molecular oxygen on the functionality of azodicarbonamide and ascorbic acid during wheat bread making.

Air, and thus also molecular oxygen (O), is incorporated in wheat flour dough during mixing. O participates in several (enzymatic) reactions, including those resulting in the oxidation of free sulfhydryl groups, thereby increasing dough strength and bread volume. We here incorporated different O levels in dough by mixing dough samples for a fixed time under different modified atmospheres which led to significant changes in dough free sulfhydryl contents and bread volumes. Although altering the mixing time not only impacted how much O was incorporated in dough but also the mechanical input, the changes in dough and bread properties when using different mixing times, largely depended on differences in O uptake. When used in bread recipes, redox agents such as azodicarbonamide (ADA) and ascorbic acid (AH) impact the dough sulfhydryl contents and bread volumes. The effect of different levels of O incorporation on dough samples which contained ADA or AH was studied by altering the mixing time or the O content in the mixing atmosphere. Lower ADA levels were needed when dough was mixed under an atmosphere enriched in O. As AH requires O to be converted to dehydroascorbic acid (DHA) to exert its improver effect, it came as a surprise that when it was included in a dough which was prepared under O enriched conditions, no additional impact was obtained and that, even under reduced O conditions, its use still resulted in an increased bread volume. These findings suggest that AH oxidase very effectively uses O to form DHA.