Pollution Research Paper

DECOLOURIZATION AND DEODOURIZATION OF SOYABEAN OIL BY ACTIVATED CARBON

GEETESH GOYAL AND ANJANI K. DWIVEDI

Abstract

Crude fats and oils contain varying quantities of impurities such as phosphatides, mucins, free fatty acids, dyes and substances which affect the odour and colour. (Erickson et al., 1980). These impurities are removed at various steps in the conventional chemical refining, which includes degumming, neutralization, washing, drying, bleaching, filtration, and deodorization. Degumming is done to remove phosphatides. Hydratable phosphatides can be precipitated by adding water to the oil, nonhydratable phosphatides must be destroyed by adding acids. Free-fatty acids are removed by neutralization with alkali hydroxides leading to soaps which can be removed. Undesirable coloured impurities are removed by bleaching with an adsorptive reagent. The undesirable compounds are adsorbed and can be removed together with the adsorbent by filtration. The last step is deodourization and by this step undesirable volatile and odoriferous materials are removed. During decolorization and deodorization process many antioxidant get lost. Soyabean oil contains luxury antioxidants like tocopherols, flavonoids, ascorbic acid, carotenoids, phytosterols. The percentage of loss of antioxidant is less in Activated carbon process. The experiment shown that FFA in crude oil reduces from 0.8% to 0.06% in both process which is in acceptable limit, Moisture and volatile in crude oil 0.6% to 0.1% in conventional process and up to 0.11% in Bleaching by Activated carbon process which is in limit, Peroxide value reduce from 1.7 ppm to 0.18 ppm in case of earth while in 0.2 in case of activated carbon which is same, % Phosphatides reduce from 936 ppm to 6 ppm by Activated carbon and up to 4.5 ppm by Earth which is in under limit. Colour reduction is from 38 unit to 13 unit by activated carbon while color reduce to 16 unit by Earth, hence colour reduction is better in case of activated carbon. Order reduction is almost same in both cases. In accordance with the improved refining process by activated carbon of the present invention, it is possible to eliminate two conventional refining steps such as Neutralization and water treatment. Despite the eliminated steps, the end product refined Oil is acceptable with respect to prevailing industry standards for taste, odor, and color. This conventional step elimination is possible because activated carbon treatment reduces phospholipids and FFA up to acceptable limit and is, moreover, storage stable. Therefore activated carbon method reduces power consumption. This is extra added advantage.