What follows is a generic description of the process involved in getting oils out of seeds (or in this case coconut copra) and onto your grocer’s shelves.
Copra (about 64% oil content) from the warehouse bin is fed to a belt conveyor where dirt and other foreign materials are manually removed. Metallic objects are disposed off by means of magnets strategically installed along the conveying lines. The cleaned copra next passes through a series of size reduction equipment – primary grinders, secondary grinders and flakers, where the size is reduced to about 1/8”. The material is then, conveyed to the driers where the final moisture is adjusted to 2%-3%. The cooked/dried copra is fed to the expellers for extraction of the oil by means of mechanical pressing to about 15%-18% residual oil in the cake. Expeller oil, containing fine solids, is conveyed to the filtration section for purification then pumped to the storage tanks.
So far so good. However, we’re not done.
Copra cake from the expellers goes to the solvent extraction plant where it undergoes continuous washing with hexane for more efficient extraction of oil from the meal. This chemically extracted oil is pumped to the filtration section for blending with the expeller oil and purification.
(Unfortunately, trace amounts of hexane remain. Is this a problem? Yes. Hexane is a petroleum based solvent that can seriously impact health. Side effects from exposure to hexane include dizziness, drowsiness, dullness, headache, nausea, weakness, unconsciousness, and abdominal pain. As a side note, hexane tends to concentrate in the meal, which is sold as animal feed. Excessive amounts of solvent in meal causes anemia in livestock. Hexane compounds are carcinogens according to the Environmental Protection Agency and are classed as a hazardous substance. Hexane also poses a serious environmental threat as it is a hydrocarbon polluter and produces ozone and air pollution when it is vented into the atmosphere during the flash off cycle. Incidentally, hexane is the solvent of choice in extracting most “natural” vitamin isolates. That means there are traces of hexane in most vitamins that you buy. But more on that in another newsletter.)
Once extracted, the oil “needs” to be refined. The refining process involves the treatment of the crude oil with a lye solution to reduce the Free Fatty Acid (FFA) content to a final value of 0.05%. This is done primarily to prevent spoilage, to help your oil last an eternity on the grocer’s shelf. (Note: Free fatty acids are not necessarily bad. Conjugated Linoleic Acid (found in meat and dairy products) is a naturally occurring free fatty acid that has been shown to improve nutrient usage, promote muscle tone, significantly reduce body fat, and have anti-tumor properties as well.)
In addition, other impurities in the oil such as gums, phosphatides, pigments and other oxidation products which would “impair” the taste, odor, keeping quality, and other “desired” properties of the oil are, likewise, removed. This degumming and neutralization process is accomplished by means of phosphoric acid and more lye. The now “neutral” oil is next mixed with bleaching earth (a type of clay) and activated carbon for reduction of the color. Final purification is effected by means of filters presses and polishing filters, then pumped to the storage tanks.
All edible oils and fats contain certain compounds which give the particular oil its identifiable taste. In all commercial oils, these compounds are removed to make the oil as neutral tasting as possible. This is process is called deodorization and because of the temperatures involved is the part of the process most damaging to the oil.
Refined bleached oil from the refining section is first transferred to a de-aerator operating under a vacuum for removal of any entrained air. The oil then passes through a series of heaters where the temperature is raised to the level desirable for efficient steam distillation and deodorization process.Temperatures used in a deodorizing steam column reach upwards of 200° C, or 450° F. At these temperatures, the fundamental structure of the oil is changed into a different form of fatty acid in a process called isomerization, a form not beneficial to the human body. As a side note, the high heat also causes a small amount of trans fatty acids to be formed.) Live steam is blown in at the bottom of the column to vaporize the odor and taste imparting components from the bulk of the oil. The fully deodorized and refined oil is withdrawn from the column passing to a cooler and polishing filter basket for removal of any fine suspension before being finally pumped to the storage tank.
The final result is an oil that is virtually colorless, odorless, and tasteless – that can last for years in a bottle with no danger of spoilage. On the other hand, it has virtually no connection with the beneficial oil that was originally contained in the seed or coconut. It is now a “plastic fat” that offers no benefits to the human body and the potential for much harm.
Choosing a Healthy Oil
The bottom line is that when possible buy and use organic, unrefined, cold-processed vegetable oils. Use olive oil in salads. Use avocado oil for cooking. Avocado oil has a very high smoke point by comparison to other cooking oils. It will not burn or smoke until it reaches 255°C, which is ideal for searing meats and frying in a Wok. Another good cooking oil is rice bran oil. Again, look for organic, cold-processed oil.
PS: And, of course, it goes without saying that anything that contains hydrogenated or partially hydrogenated oil is an absolute no-no, and should be avoided in the same way that one should avoid playing Russian Roulette..