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

[Display omitted] •Dough mixing time impacts bread volume by impacting how much O2 is incorporated.•Azodicarbonamide compensates for low levels of O2 in dough and vice versa.•Ascorbic acid unlike azodicarbonamide needs O2 to enhance bread quality.•Even when dough contains little O2, ascorbic acid enhances bread quality. Air, and thus also molecular oxygen (O2), is incorporated in wheat flour dough during mixing. O2 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 O2 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 O2 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 O2 uptake. When used in bread recipes, redox agents such as azodicarbonamide (ADA) and ascorbic acid (AH2) impact the dough sulfhydryl contents and bread volumes. The effect of different levels of O2 incorporation on dough samples which contained ADA or AH2 was studied by altering the mixing time or the O2 content in the mixing atmosphere. Lower ADA levels were needed when dough was mixed under an atmosphere enriched in O2. As AH2 requires O2 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 O2 enriched conditions, no additional impact was obtained and that, even under reduced O2 conditions, its use still resulted in an increased bread volume. These findings suggest that AH2 oxidase very effectively uses O2 to form DHA.