Demystifying oils and fats, part three

Processing of Oils

The highest-quality oils are called first cold-pressed or extra virgin, and they are unheated, unfiltered and unrefined. The name refers to a traditional method that is no longer widely used. Today, many commercially processed oils are “pressed” in a centrifuge. No heat is applied during extraction, so the initial process can still rightfully be called “cold pressed.”  But in a second step, steam (heat) and solvents are used to extract more oil from the leftover pulp, producing an oil of inferior quality. In the case of olive oil this oil may be called olive pomace oil or pure olive oil.

Generally, high pressure, heat and chemical solvents are used to squeeze the oil out of corn, grape seeds, safflower seeds and soybeans. These oils have high polyunsaturated fatty acid content, so they already become rancid in the manufacturing process. The rancid oils are then deodorized—with the help of more harmful chemicals—in order to be made palatable. For these reasons, please stay completely away from refined corn, grape seed, safflower, and soybean oils. Remember, if it is not specifically stated, that an oil is unrefined you may assume it is refined and therefore compromised.

Polyunsaturated oils also come from sunflower seeds, walnuts, sesame seeds and wheat germ.  If you can find unrefined versions of these oils, feel free to use them cold in dressings or simply sprinkled over your cooked food once it is served.  Buy flaxseed oil only if it is contained in an opaque dark bottle and was kept refrigerated until your purchase.  Keep all these last mentioned oils in the refrigerator.

Finally, I would like to address the issue of hydrogenated oils, partially hydrogenated oils and trans fats. In essence these are all the same thing. While hydrogenation is the manufacturing process, trans fats are the outcome. All hydrogenated and partially hydrogenated oils contain trans-fats. Food companies wanted to create a cholesterol-free, easy-to-spread product with a long shelf life—and margarine came into being. But you can find partially hydrogenated oils even in processed liquid vegetable oils.

Hydrogenation is a manufacturing process that uses high temperature and high pressure to force hydrogen gas into polyunsaturated fatty acids in order to solidify them. In essence, the hydrogen atom breaks into the double bond, takes out the bend, and straightens out the fatty acid chain.  The polyunsaturated fatty acid has thus been transformed into a so-called trans fat. Now it behaves more like a saturated fatty acid and packs together well to form a semi-solid mass.

But trans fats are biochemically incompatible with the human body. In fact, their chemical makeup resembles that of plastic. After hydrogenation, the original vegetable oil has turned into a grey, ill-smelling mass. This mass then gets bleached and deodorized, again with the help of harmful chemicals. As a last step, a yellow dye is added to make the product appear more butter-like.

The human body is unable to metabolize trans fats. They remain in the bloodstream and are likely to collect on the artery walls as plaque, which can lead to coronary heart disease. Other conditions associated with trans fats are Alzheimer's disease, cancer, diabetes, obesity, liver dysfunction and infertility in women.

For decades, margarine has been touted a health food, when it clearly is not. Even today, although trans fats are in the news and have been recognized as a serious health hazard (in New York City, restaurants are prohibited from cooking with trans-fats), some medical professionals still recommend eating margarine over butter for heart health.

To sum it up:

Please always choose extra virgin or cold pressed oils – that guarantees the highest quality of oils.

Please stay away from all refined oils, even those in the health food store. What the health food store has going for it is the fact that they at least point out to you on the label – which oil is refined and which oil is unrefined. Always prefer the unrefined versions.

Please stay away completely from partially hydrogenated and hydrogenated oils, including so called “vegetable oils” found in supermarkets, margarine and shortening. And because most commercially produced baked goods are made with margarine or shortening it is advisable to stay away from those too. Rather bake your own cookies and cakes and use good old fashioned butter in the process.