Effects of filtration through bleaching media on thiobarbituric acid and carbonyl values of autoxidized soybean oil

Abstract

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.

Interactions Among Oil Components During Adsorption: Effects on Carotenoids and Peroxides

“…The process of bleaching, mainly designed for pigment removal (Taylor et al, 1989), has also had effects on the removal of trace metals, phospholipids (Brown and Snyder, 1989), peroxides (Nkpa et al, 1989;Toro-Vazquez, 1990;Toro-Vazquez et al, 1990) as well as products of peroxide decomposition (Boki et al, 1989(Boki et al, , 1990. Bleaching is the only step in the refining of vegetable oils that uses adsorption.…”

Adsorptive bleaching of soybean oil with non‐montmorillonite Zambian clays

“…In view of its relatively unsaturated nature, soybean oil is particularly prone to oxidative rancidity (5). This process is catalyzed by the presence of metals or other radical initiators (6).…”

A comparison of the effects of various purification treatments on the oxidative stability of squid visceral oil

“…This phenomenon also might be due to adherence of phospholipids on the glass distillation chamber or tubing during molecular distillation. Alumina, used for chromatography, and Sep-Pak cartridges reportedly adsorb polar compounds (9). It should be noted that refined oil after alumina adsorption (A oil) showed a significant decrease in the concentration of total phenolics concentration as shown in Table 1 (P < 0.05).…”

“…A similar phenomenon was observed for phospholipids. Boki et al (9) reported that such a decrease is due to the strong adsorption of polar compounds to the alumina phase. The results suggested that polar compound adsorption on alumina was irreversible but that this interaction was lower in the Sep-Pak cartridge, as indicated by the partial release of polar compounds from Florisil-type Sep-Pak cartridge when eluted with hexane.…”

“…Ferrari et al (8) showed that the level of total tocopherols decreased after deodorization. Boki et al (9) described how hydroperoxides, aldehydes, and ketones were adsorbed on bleaching media, such as aluminum oxide, activated clay, activated carbons, and other commercial adsorbents. Investigation of the oxidative stability of soybean oil at the various stages of refining has shown that crude oil is the most stable and that highly purified soybean TG is the least stable (5,10).…”