Optimization of Composite Decolorizer Efficacy Based on Decolorization Efficiency, Toxicity, and Nutritional Value of Rice Bran Oil

This study compared the effect of five different adsorbents (activated clay, activated carbon, attapulgite clay, bentonite, diatomite) on the levels of nutrients, harmful substance retention, and decolorization in rice bran oil. Among the adsorbents tested, activated carbon displayed the highest decolorization efficiency (82.90%) and adsorption effect on 3,4-benzopyrene (BaP, 89.53%) and 3-monochloropropane-1,2-diol ester (41.55%), whereas activated clay had the highest oryzanol retention percentages (85.98%) and affordability. Activated carbon and activated clay were therefore selected as composite decolorizing agents. Based on single-factor and Box-Behnken response surface tests, the optimal conditions for decolorization efficiency (97.08%), oryzanol retention (89.62%), sterol retention (90.16%), vitamin E retention (79.91%), and benzo(a)pyrene adsorption percentages (95.98%) were determined to be achieved by using a 5% (w/w) composite decolorant (activated clay:activated carbon=5:1), at a temperature of 116℃, with an incubation time of 33 min. This study provides evidence to support the efficacy of compound decolorants, which may have practical use in large-scale industrial applications of edible oil decolorization during refinement.