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

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.