Effect of reducing agents and baking procedure on the residual bromate in bread (The study of bromate residues in bread Part 1)

Abstract

Potassium bromate, which contributes to the formation of disulfide bonds in wheat protein in dough and increased gas-retaining capacity, has been used as a bread improver since the 1910s. However, it has been reported that potassium bromate has a mutagenicity based on experiments with rats. Thereby, the regulations in Japan stated that in the case of bread, residual bromate must be reduced or removed from the final products. Residual contents of potassium bromate in bread extracts prepared by the improved method were measured by high performance liquid chromatography (HPLC) with post-column reaction for the coloring of bromate. No residual bromate was detected in Pullman-type breads with 13 or 15 mg potassium bromate added per kg of flour. On the other hand, the residual bromate determined in open-top type bread with 9-30 mg potassium bromate added per kg of flour, was found localized on the top of crust put out of the baking pan. Reducing agents such as L- ascorbic acid (AsA), cysteine and glutathione and ferrous sulfate were added to the open-top type bread to reduce the residual bromate. Adding both AsA and ferrous sulfate accelerated the decrease in the residual bromate in the open top-type bread.