Determination of benzoyl peroxide and benzoic acid levels by HPLC during wheat flour bleaching process

Freshly milled wheat flour has a pale yellow color due to its carotenoids c ontent. Benzoyl peroxide is a bleaching agent typically used to give such f lour a better appearance. This free-radical initiator promotes carotenoids oxidation, thereby producing less colored compounds, and benzoic acid is a main final product. Samples of wheat flour were treated with 150 ppm of ben zoyl peroxide to begin a bleaching process, and then subjected to ethyl eth er extraction at different intervals of time. Benzoyl peroxide and benzoic acid levels in these extracts were monitored by means of HPLC in individual experiences. The resulting concentration of benzoyl peroxide after 9 days of contact with the bleaching agent was 11 ppm, dropping afterward to nonde tectable levels. A maximum value for benzoic acid of 16 ppm was found after 12 h of bleaching. Subsequently this level decreased continuously until re aching a residual value of 6 ppm after 3 months.