ENHANCING OF THE PERFORMANCE EFFICIENCY OF OILS BLEACHING EARTH

Various percentages of citric acid [0.05, 0.1, 0.15 and 0.2%] were blended with the oil (w/v) before the bleaching of either soybean oil (SOO) or sunflower oil (SUO) to rise the performance efficiency of bleaching earth. Afterwards, activated bleaching earth was added to these oils for bleaching them at 1% level. Also, the same clay was used at 2% level for bleaching the above mentioned oils without us-ing citric acid as a reference. The study revealed that better result for raising the bleaching efficiency of SOO was obtained with 0.15% citric acid. Whilst, 0.1% cit-ric acid gave the best result pertaining the bleaching efficiency of SUO. Also, the data showed high reductions in the values of peroxide number, soap, conjugated dienes and trienes for the bleached oils with the increasing percent content of citric acid. While, the acidity values of the bleached oils (SOO and SUO) slightly in-creased with increasing citric acid percentages. On the other hand, using of citric ac-id at the ratios of 0.15 and 0.2% gave almost the same values in the bleaching effi-ciency of SOO. While, using of citric acid at the ratios of 0.1 and 0.15% gave nearly the same results of bleaching efficiency of SUO. Also, the data indicated that using of citric acid caused somewhat no changes in the fatty acid composition or their oxi-dative stabilities in the bleached oils. Therefore, it can be concluded that the reduc-tion in the color of sunflower and / or soybean oils up to a levels of 33.3 and 36.7% is attainable by using either 0.1 or 0.15% citric acid prior to the bleaching step to de-crease the imported content from bleaching earth to Egypt