Refined Soybean Oil

Soybean belongs to the family of Fabaceae (Leguminosae). This type of oil has a great lipid profile. In healthy proportions, it has polyunsaturated, monounsaturated, saturated fats. Refined Soybean Oil is one of the stable cooking oils and carries a long shelf life.

Soybean oil contains only trace amounts of fatty carboxylic acids (about 0.3% by mass in the crude oil, 0.03% in the refined oil). Instead it contains esters. In the following content, the expressions “fatty acids” and “acid” below refer to esters rather than carboxylic acids.

Per 100 g, soybean oil has 16 g of saturated fat, 23 g of monounsaturated fat, and 58 g of polyunsaturated fat. The major unsaturated fatty acids in soybean oil triglycerides are the polyunsaturates alpha-linolenic acid (C-18:3), 7-10%, and linoleic acid (C-18:2), 51%; and the monounsaturate oleic acid (C-18:1), 23%. It also contains the saturated fatty acids stearic acid (C-18:0), 4%, and palmitic acid (C-16:0), 10%.

The high-proportion of oxidation-prone polyunsaturated fatty acid is undesirable for some uses, such as cooking oils. Three companies, Monsanto Company, DuPont/Bunge, and Asoyia in 2004 introduced low linolenic Roundup Ready soybeans. Hydrogenation may be used to reduce the unsaturation in linolenic acid. The resulting oil is called hydrogenated soybean oil. If the hydrogenation is only partially complete, the oil may contain small amounts of trans fat.

Trans-fat is also commonly introduced during conventional oil deodorization, with a 2005 review detecting 0.4 to 2.1% trans content in deodorized oil.