Digital monitoring and response surface methodology optimization of wheat bran bleaching by hydrogen peroxide and its incorporation into wheat Flour

Abstract

What bran contains valuable molecules having high nutritional value. However, the characteristic dark color and the poor functional properties of this material make its use as an ingredient in foods very limited. Thus, to improve its potential application in the food industry, it is important to modify its color and structure by appropriate treatment. The aim of this study was to bleach wheat bran using hydrogen peroxide and optimize the bleaching conditions. Response surface methodology was employed to determine the optimal concentrations of hydrogen peroxide and wheat bran (WB), as well as the process duration required to achieve the best chromatic profile. The optimized conditions successfully eliminated the brown color of the wheat bran, resulting in a final product characterized by a chromatic profile compatible with commercial wheat flour, exhibiting the following values: L* = 78, a* = -2.6, and b* = 18.8. These results were achieved using a hydrogen peroxide concentration of 20 %, a wheat bran concentration of 10 %, and a contact time of 20 min. Under these bleaching conditions at pH 11, the resulting bran exhibited lower water retention capacity and a significantly increased extractability of dry matter in aqueous media, rising from 20 % for the unbleached bran to 90 % for the bleached bran. Additionally, when mixed with wheat flour, the results indicated a uniform color when combining wheat flour with 10 % bleached bran. In contrast, the unbleached wheat bran showed the presence of two colors on the surface of the mixtures, as revealed by digital analysis.