I had not thought twice about soy since I've been using it as a source of protein and substitutes for foods like meat and cheese. And, the news hardly ever says anything bad about it.
But, the other day I bought a brand of margarine that contained soybean oil. It made me wonder if this bean actually can have a trace of oil in it or not? So I researched and found this information quite interesting. The process of making soybean oil is as follows (based on this website: (http://www.soya.be/soybean-oil-production.php):
1) Cleaning of soybeans
The soybeans are first cleaned, dried and dehulled prior to oil extraction. The soybean hulls needs to be removed because they absorb oil and give a lower yield. This de-hulling is done by cracking the soybeans and a mechanical separation of the hulls and cracked soybeans. Magnets are used to separate any iron from the soybeans.
The soybeans are also heated to about 75°C to coagulate the soy proteins to make the oil extraction easier.
2) Extraction of soybean oil
The soybeans are cut in flakes which are put in a percolation extractors and immerged with a solvent, normally hexane (Hexanes are significant constituents of gasoline. They are all colorless liquids at room temperature, with boiling points between 50 and 70 °C, with gasoline-like odor. They are widely used as cheap, relatively safe, largely nonreactive, and easily evaporated non-polar solvents). Counter flow is used as extraction system because it gives the highest yield. After removing the hexane, the extracted flakes only contain about 1% of soybean oil and is used as livestock meal or to produce food products such as soy protein. The hexane is separated from the soybean oil in evaporators. The evaporated hexane is recovered and returned to the extraction process. The hexane free crude soybean oil is then further purified.
3) Purification of soybean oil
The crude soybean oil still contains many oil-insoluble and oil-soluble impurities that needs to be removed. The oil-insoluble material are removed with filtration and the soluble materials is removed with different processes including degumming (removing of phosphatides), alkali refining (washing with alkaline solution to remove free fatty acids, colorants, insoluble matter and gums) and bleaching (with activated earth or activated carbon to remove color and other impurities.
4) Hydrogenation of soybean oil (optional)
This process will increase the stability of the soybean oil and will make it less liquid. However, this process will create more saturated fats and will reduce the favorable unsaturated fats. In addition, trans-fats are produced. Hydrogenated soybean oil is used in foods that require more solid fat such as margarine.
So basically the margarine which I had was hydrogenated. Soybean oil doesn't really seem to be much of any nutritional value whatsoever by all the processing that it goes through and the amount of chemicals used to get it to the actual "oil" we can consume.
Bottom line is, avoid it altogether.
