EFFECTS OF FILTRATION THROUGH BLEACHING MEDIA ON THIOBARBITURIC ACID AND CARBONYL VALUES OF AUTOXIDIZED SOYBEAN OIL

Effects of filtration bleaching on thiobarbituric acid values (TAV) and carbonyl values (CV) of autoxidized soybean oil were investigated by using sixteen kinds of bleaching media in order to improve oil quality. The standard activated clay was the most effective in reducing the amounts of aldehydes and ketones in autoxidized soybean oil. From the decreases in TVA and CV and physical and chemical properties of media, it was concluded that decreases of TAV and CV are mainly dominated by the acidity over the highest range, +1.5∼-5.6, rather than the acidity over the lower acid strength ranges, total acidity or specific surface area of media. From the results of chemical composition and acidity over the highest range (+1.5∼-5.6) of the clays and TAV or CV reduction by using the heattreated clays, it was suggested that the acidity over the highest range originated from the water contained between layers and bound water in the clay. © 1990 AOCS Press.