Effects of Filtering through Bleaching Media on Decrease of Peroxide Value of Autoxidized Soybean Oil

Abstract

The effects of filtering through bleaching media on decrease of peroxide value (PV) of autoxidized soybean oil were investigated to improve its quality. Sixteen kinds of filtering and bleaching media were employed. The standard activated clay was the most effective in decreasing the peroxides in autoxidized soybean oil. The relations between the decrease of PV and the physical or the chemical properties of the media were examined. It was found that peroxides are reduced in proportion to the amount of acid at the highest acid strength range + 1.5--5.6 rather than amount of acid at the lower acid strength range, total amount of acid or specific surface area of medium.

Using Trace Metals, Peroxide, Acid and Iodine Values to Characterize Oils Bleached Using Clays from Central and Eastern Uganda

“…The reductions found in peroxide values of the cotton and sunflower seed oils after their bleaching with the different kinds of bleaching earths developed in this study agree with those presented by earlier workers, [4] [54] [61] who showed that oxidation levels are reduced by the breakdown of hydroperoxide primary oxidation product on the adsorbent surfaces such as bleaching earth. Earlier workers suggested that a decrease in peroxide value is due to the decomposition of peroxides by the strongest acid on the surface of bleaching earth [4]. However, it is expected that peroxide values would be higher if the oils were stored for long to encourage rancidity.…”

Effects of filtration through activated carbons on peroxide, thiobarbituric acid and carbonyl values of autoxidized soybean oil

“…Filtration through activated carbon. Filtration through activated carbon was carried out by the method described previously (2). The decreases in PV, TAV and CV were obtained by treating 10 g autoxidized soybean oil (PV, 45.1 meq/kg; TAV, 1.0; CV, 10.5) with 1 g activated carbon.…”

“…The standard activated clay effectively reduces the peroxide value (PV) (2), thiobarbituric acid value (TAV) and carbonyl value (CV) (3) of autoxidized soybean oil. Boki et al (2,3) indicated that peroxides are decomposed by the strongest acid sites on the clay and that aldehydes and ketones are adsorbed on their active sites.…”

Changes in Edible Fats and Oils During Processing

“…Natural clay is used if the oil is readily bleachable. However, acid-activated clay is usually used because its bleaching power is greater than that of the natural clay (Boki et al 1989;Morgan et al 1985;Richardson 1978).…”