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

Abstract

Bleaching of edible oils is known to alter the composition of oils as it removes impurities and certain food nutrients. The characteristics of bleached oil are strongly related to type bleaching medium, temperature at which bleaching is done and other factors. In this study, we compare peroxide, free fatty acid, acid and iodine values, copper and iron content of bleached and crude oils to establish the characteristics of edible oils bleached using smectite and kaolinite-rich clays. Oil industries spend large sums of money purchasing bleaching earths yet no country lacks natural clays which can be developed to bleach oils. In Uganda alone more than US$ 700,000 is spent every month yet many clay deposits are unexploited. In this study,

Optimization of sunflower oil bleaching parameters: using Response Surface Methodology (RSM)

“…Ot is an absorption process that involves the use of the acid-activated clay to remove undesirable oil components (Nwabanne & Ekwu, 2013). Some oils may contain colored compounds that are not desired by the consumer; therefore, they should be bleached to improve their color (Mukasa-Tebandeke et al, 2014). The color improvement is due to the removal of organic compounds such as carotenoids, particularly β-carotene and their derivatives, xanthophylls, chlorophylls, pheophytins, tocopherols, gossypol, and their degradation products; these can all transmit an undesirable color to oil (Dkolo & Adejumo, 2014).…”

Fatty Acids Composition and Physico-Chemical Constants of Punica Granatum L. Seed Oil

“…The level of unsaturation of the oils may be expressed by the iodine numbers. The peroxide value of oil is important property for the measurement of extent to which rancidity is produced due to autoxidation [22]. For this reason we also conducted a study of the physico-chemical constants and organoleptic properties of P. granatum L. seed oil.…”

Influence of Chemical Composition of Activated Calcium Bentonites and Sodium Bentonites on Palm Oil Bleaching Capacity and Oil Quality

“…Bleaching is one of the most important steps in vegetable oil refining; in this step, pigments and undesirable impurities are removed by a process involving van der Waals forces and covalent bonds (Nwabanne and Ekwu, 2013). The efficiency of palm oil bleaching has been reported in many types of adsorbents such as palm oil boiler ashes, activated coconut pod ash, perlite, smectite, activated kaolinite, pyrolysis waste material peanut hulls, press mud, rice husks and synthetic (Ismail et al, 2016;Lau et al, 2019;Meesuk and Seammai, 2010;Rossi et al, 2003;Warasith and Goodman, 2020;Tebandeke et al, 2014). However, adsorption materials used nowadays throughout the world by vegetable oil refiners are mainly activated montmorillonite clays due to its structural unit consisting of an octahedral alumina sheet sandwiched between two sheets of tetrahedral silica.…”