Characterization of Oils Bleached with Clays Using Trace Metals, Peroxide, Acid, and Iodine Values


By eliminating impurities and certain food components, edible oil bleaching is known to alter the composition of oils. The features of bleached oil are influenced by a number of factors, including the type of bleaching medium used, the bleaching temperature, and other factors. We analyse the peroxide, free fatty acid, acid, and iodine values, as well as the copper and iron content of bleached and crude oils to identify the features of edible oils bleached using smectite and kaolinite-rich clays. Even though every nation has naturally occurring clays that can be used to bleach oils, oil firms still spend a lot of money on bleaching earths. Even though many clay reserves are yet unexplored, more than US$ 700,000 is spent in Uganda alone each month. This research examined the trace metal composition, peroxide, acid, iodine, and free fatty acid contents of bleached and unbleached cotton-seed and sunflower seed oils. It was determined that the bleached oils were suitable for human consumption. Since silicon dioxide and aluminium oxide are ubiquitous minerals, clays are generally referred to as alumino-silicates. Clays are either kaolinites or smectites, however to bleach edible oils, montmorillonites or bentonites are used. Of all the bleached oils, the bleached oils had the most iron content decrease. The element with the least change was copper. When Kajansi clay was leached in 20% acid, the copper level in cotton oils reduced from 0.5 ppm to 0.15 ppm, while when Chelel clay was leached under the same circumstances, the decline was from 0.5 to 0.1 ppm. Iron content in sunflower oils reduced from 1.6 to 0.2 ppm when bleached with Kajansi clay leached in 20% acid, whereas it only decreased to 0.1 ppm when bleached with Chelel clay under the same circumstances. Since oleic acid has an average value in the spectrum of acids, it is principally responsible for the acidity of sunflower oils, whereas linoleic acid corresponds to cottonseed oil. For all of the clays utilised, the amounts of free fatty acid were found to vary from 3.8 to 3.2, exhibiting no discernible increase. Bleached oils had peroxide levels ranging from 1.2 to 0.8.

Author(s) Details:

Is’harq-Zubair Mukasa-Tebandeke,
Department of Chemistry, Makerere University, Uganda.

Pancras John Mukasa Ssebuwufu,
Department of Chemistry, Makerere University, Uganda.

Steven A. Nyanzi,
Department of Chemistry, Makerere University, Uganda.

Andreas Schumann,
Department of Geology, Makerere University, Uganda.

George W. Nyakairu,
Department of Chemistry, Makerere University, Uganda.

Festo Lugolobi,
Department of Earth Sciences, Wesleyan University, USA.

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Keywords: Bleached oil, clays, trace metals, peroxide, iodine.

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