Fate of contaminants during the refining process of vegetable oils and fats: A calculation model

Abstract

Crude vegetable oils and fats after oil extraction may contain contaminants introduced in the supply chain. Many of these contaminants are largely removed from the oil by the refining process. However, these contaminants will concentrate in the refinery by‐products; acid oil from soapsplitting and filter blowing, spent bleaching earth, and deodorizer distillate. The contaminant levels in these by‐products are calculated by determining the lipids balance of the refinery and the fate of the contaminants in the refining process. Calculations of some example oils with characteristic contaminant levels show that deodorizer distillate from chemical refining has a high‐contamination risk, deodorizer distillate from physical refining and spent bleaching earth has a medium risk, whereas acid oil from soapsplitting and filter blowing have a low‐contamination risk.Extracted oils and fats contain impurities like free fatty acids, phospholipids, etc., and may contain contaminants like polycyclic aromatic hydrocarbons and pesticides. The impurities and some entrained oil form the refinery by‐products; acid oil, spent earth, and deodorizer distillate. The contaminants will concentrate in these by‐products. For application in animal feed, acid oil is relatively safe (green), oil from spent bleaching earth requires contaminant analysis (orange), whereas contaminant levels in deodorizer distillate are often too high for use in feed (red).