Production of Thiyl Radical on Soluble Glutenin by Superoxide Anion Radical

The role of superoxide anion radical (O-2(-)) in the improvement of bread dough by L-ascorbic acid (AsA) was examined. Since AsA makes detection of thiyl radicals (S center dot) difficult, riboflavin was used as a photoinduced O-2(-) producing agent in substitution of the classical improvement molecule. The preparation of soluble glutenin was successfully achieved by means of deamidation using protein glutaminase. Electron spin resonance (ESR) spectroscopy coupled with spin trapping revealed the presence of photoinduced S center dot in a solution containing riboflavin and soluble glutenin. Unlike catalase, addition of superoxide dismutase suppressed the production of S center dot in the soluble glutenin. These results suggest that the O-2(-) produced during the oxidation of AsA in dough is responsible for the generation of S center dot in gluten proteins, thereby increasing the production of inter-protein disulfide bonds and resulting in an improved bread structure.