Effect of Selected Polyhydric Alcohols on Refining Oil Loss in the Neutralization Step

Alkaline neutralization is a classical method for removal of free fatty acids (FFA) in crude oil. It is generally accompanied by neutral oil loss. Thus, reduction of refining losses associated with alkaline neutralization is very desirable. Refined, bleached and deodorized (RBD) palm oils with different FFA contents were used as oil models in this study. FFA in the oil models were neutralized with sodium hydroxide in polyhydric alcohols as neutralization media. Glycerol, propylene glycol and ethylene glycol in water were effective neutralization media. FFA in the oil models were totally removed in one step of neutralization, while percentages of refining losses were different. The losses were increased in the order of water > propylene glycol > ethylene glycol > glycerol used as neutralization media. Also, a higher concentration of polyhydric alcohol in the neutralizing media significantly reduced the percentage of refining loss (p < 0.05). Glycerol (90% in water) was the most effective neutralization media (p < 0.05). When neutralization was carried out on crude palm oil (containing 7.53% FFA), refining loss was reduced from 36.1% (in water) to 20.0% (in 90% glycerol in water).