Effect of chemical refining on the levels of bioactive components and hazardous substances in soybean oil

Abstract

Tocopherols and phytosterols are bioactive components naturally present in vegetable oils, while trans fatty acids (TFAs), polycyclic aromatic hydrocarbons (PAHs) and 3-monochloropropane-1,2-diol esters (3-MCPD esters) are harmful components that frequently occurring in edible oils. The study is aiming to evaluate changes of these components in soybean oil at each step during chemical refining. After refining, the concentrations of tocopherols, phytosterols and PAHs decreased from 1411.1 mg/kg, 2578.0 mg/kg, and 45.3 µg/kg to 1063.6 mg/kg, 1354.6 mg/kg, and 3.7 µg/kg, respectively. However, the concentrations of TFAs and 3-MCPD esters increased from 0.11% and 25.5 µg/kg to 1.08% and 320.2 µg/kg, respectively. The most significant reductions in phytosterols (56.5% of total reduction) and PAHs (67.0% of total reduction) were attributed to neutralization, while the most significant reduction in tocopherols (47.8% of total reduction) was attributed to deodorization. Meanwhile, deodorization contributed most to the increases of TFAs (96.9% of total increment) and 3-MCPD esters (64.9% of total increment). This work could provide guidance for soybean oil processing with respect to minimize the amounts of hazardous substances while maintain the contents of bioactive components.