Bleaching of defatted flaxseed meal to improve its usage as ingredient in food applications

Abstract

Summary Brown defatted flaxseed meal (FM) was decolourised by dilute hydrogen peroxide (HP). The bleachability was evaluated as function of the FM concentration (2.5%, 5% and 10%), HP concentrations (1%, 2% and 3%), pH (3, 6, 7 and 9), temperature (25, 50 and 75 °C) and reaction time (2, 5 and 10 min). The product whiteness and yellowness were better at pH 9% and 3% HP concentration. The bleachability was enhanced by increasing the temperature but was inversely proportional to the meal concentration. The colour L* value was the highest at 2.5% FM, 3% HP, pH 9 and 10 min at 75 °C (L* = 74.82 ± 0.56) and was the lowest at 10% FM, 1% HP, pH 3 at 25 °C during 10 min (L* = 36.17 ± 0.45). These results may be exploited to improve the profitability of the flax sector using bleached meal as ingredient in food formulations.