Release of 14C-labelled carbon dioxide from ascorbic acid during straight dough wheat bread making

BACKGROUND AND OBJECTIVES: The redox agent L-ascorbic acid is included in wheat bread recipes for the dough strengthening and bread volume enhancing effects it brings about once converted into dehydro- L-ascorbic acid. We here used different dosages of ascorbic acid along with ¹⁴C₁-labeled ascorbic acid to measure the loss of its C₁-atoms as carbon dioxide during dough fermentation and bread baking. FINDINGS: The loss of carbon dioxide from ascorbic acid, dehydroascorbic acid, or other components formed therefrom is mainly thermally induced. Higher dosages of ascorbic acid resulted in lower portions thereof losing their C₁-atom during baking with 80% or 59% of its C₁-atoms lost when dosing 10 or 300 ppm ascorbic acid (on flour base), respectively. Given the limited amount of molecular oxygen, which is needed for the conversion of ascorbic acid into dehydroascorbic acid, available in dough, a lower percentage-wise conversion of the former into the latter is expected at a higher ascorbic acid dosage, which seems to be linked to a relatively lower percentage-wise loss of C₁-atoms. CONCLUSIONS: It was concluded that dehydroascorbic acid has a pivotal role in the reactions leading to ascorbic acid decarboxylation and its reaction products. SIGNIFICANCE AND NOVELTY: Due to the increasing awareness of correct food product labeling, it is important to understand to which extent ascorbic acid is degraded during bread making.