The use of calcium sulphate dihydrate (CaSO₄.2H₂O) as a bleaching agent for crude soya bean vegetable oil

The use of calcium sulphate dihydrate (CaSO4.2H2O) as a bleaching agent during the refining of crude soya bean vegetable oil was investigated. Different weight ratios of CaSO4.2H2O bleaching agent relative to crude oil (2, 4, 5, 10, 20 and 30 wt. %) were prepared. One sample of raw crude without any bleaching agent added was isolated as a control. Each of the 7 crude oil samples were preheated at a temperature range of 80ºC - 120ºC.The different weight compositions of CaSO4.2H2O were added and the respective slurries agitated for 30minutes.The agitated slurry was then filtered. The experimental results for red color were recorded and % free fatty acids (ffa) and % bleachability were calculated. The results indicated that there was decrease in red color of crude oil from 14R-4.3R with increase in weight ratio of bleaching agent. There was also an increase in red color bleachability from 24.285 % - 60.714% with increase in weight ratio. % ffa and solid nonfat (SNF) remained constant at 0.56% and nil respectively. The results indicate that calcium sulphate dihydrate (CaSO4.2H2O) is an effective bleaching agent in bleaching of crude soya bean vegetable oil.