Truth About Fats III: The Story Behind Vegetable Oil – The Kitchen Rag

chorazinolivepress-1-300x225-6631126This post is dedicated to decoding vegetable oil labels and finding oils that offer healthy, living supplement of omega – 6 fatty acids. There are three major methods of extracting oils from nuts and seeds: the cold pressed method, the expeller method, and the solvent method.

Oil Extraction Methods

The Cold-Pressed Method

The cold pressed method is the best method of extracting oil without oxidizing it. Most large companies will use heavy granite or stainless steel presses. While some heat is generated by the friction, it must remain below 120* F (49* C) in order to be labeled cold pressed in the US. These  parameters change when you purchase cold pressed oil from any of the countries in the European Union, where the limit is 80* F (27* C). If the heat goes above this temperature, the labels will say “pressed” as opposed to “cold pressed’.

The lower the temperature, the more of the wonderful properties will be retained. From an experiential point of view, the best way to tell whether an oil is truly cold pressed is by tasting it; just like a fine wine the oil will be bursting with rich flavor, color, and aroma. Not all vegetable oils can be completely cold pressed. The ones that yield enough oil for production with very limited heat during extractions are olive and sesame oil. These two oils are some of the oldest oils utilized by civilization. Our bodies recognize them instantly and take advantage of all of their wonderful properties.

Expeller Pressed

The expeller method presses the oils out of seeds and nuts at a very high pressure. This pressure can heat the oils up to 400* F. There is no added heat except the temperatures that rise during crushing. Some extraction temperatures can go really high depending on the type off nuts or seeds. While some oils, like sunflower, grape seed, flax, wheat germ, pea nut, and coconut, can be extracted through both the cold pressed and the expeller pressed methods, canola oil, cotton seed oil, soy bean oil, and corn oil, can only be extracted with additional high heat via expeller method with the help of chemical solvents. I would like to expand more on such oils that cannot be cold pressed, but there is so much valuable information on each one of them that future posts will be dedicated to them.

Solvent Extraction

Solvent extraction goes hand in hand with the expeller method.  Even crushing at high temperatures yields only about 60% of the oil from seeds and nuts. Certain organic oil companies draw the line here and thus are allowed to label their oils “crude” or “unrefined”. However, most large corporations, naturally more invested in cost-effectiveness than consumer health, will take the steps required to extract the remaining oil, and use toxic chemical solvents like hexane, pentane, heptane. The end product has to be deodorized and bleached to remove the residual petroleum odor. This process removes not only the stench of synthetic chemicals, but also vitamins and antioxidants. This post has some more information about the solvent extraction.

Solvents such as benzene and toluene, have been linked to numerous cancers. Benzene, specifcally, has been  repeatedly associated with rheumatoid arthritis – an auto-immune condition in the joints that affects over 2 million adults in the US. Not only are these toxic substances harmful singly, but when combined, as they are in commercially grown and processed food and in the human body where they accumulate, their effects have been found to be magnified as much as a 1,000 fold.
George Mateljan, The World’s Healthiest Foods, Page 229

Olive Oil


Olive oil is one of the few vegetable oils that can stand being heated at medium heat. It has only one unsaturated carbon bond, which makes it more stable that other polyunsaturated oils like sunflower, flax, wheat germ, etc. There are two reasons I am dedicating some time to it in this post: 1) its popularity; 2) olive oil has a variety of extractions options. I find purchasing olive oil at the grocery store extremely challenging.

After some research this is what I have been able to find out:

Olive oil was probably discovered around 4000 BC in Asia Minor. Very quickly, it became the food of the gods. The rich, green-gold oil was used for cooking, skin care, religious rites, and fuel, and more. It quickly became essential to every house hold. The Latin word for both olive tree and oil is oleum, the root of modern word for oil. The Mediterranean world continues to have the best olive oil produced in the world. While the US, New Zealand, Brazil, Australia, and others produce olive oil, Greece, Italy, Spain and Portugal are most well known known for their outstanding cold pressed, extra virgin olive oils. Everyone knows that extra virgin olive oil can be quite pricy. Why is extra virgin oil so expensive?

Extra Virgin

According to the International Olive Oil Council extra virgin olive oil can not not be heated beyond 80* F (30* C). It has a free acidity, expressed as oleic acid, of no more than 0.8 grams per 100 grams. A high oleic acid reflects a lower grade fruit, and a higher pressing temperature. These standards have unfortunately not been adopted in some of the US. As a result, oils of lower grades can be labeled as “extra virgin” olive oils. Since olive oils from the European Union are subject to stricter standards, I would highly recommend them, despite the higher prices. Polysaturated omega-6 fatty acids are highly sensitive to light, oxygen, and heat; consequently, I try to find the highest quality oils of this kind that I can.


The difference between extra virgin olive oil and virgin olive oil is the acidity content. Virgin olive oil has a higher acidity content: 2 grams per 100, versus extra virgin’s .8 per 100.


Pure olive oil is usually a combination of virgin olive oil and expeller pressed olive oil. Oil companies sometimes add some virgin olive oil to the expeller pressed oil to make it smell and taste better.

“Olive Oil”

If you see a bottle that just says olive oil, it is highly refined, the fruit was crushed under a high heat, and the quality of the fruit is inferior.


The very worst olive oil is the pomace oil. This oil is extracted from the left over olive pulp after the first press, with the aid of chemical solvents. Fortunately after pressure from the International Olive Oil Council, companies are not allowed to label this product olive oil, and must instead say “pomace olive oil”.

Part 4

In the next post I will continue the discussion on vegetable oils by introducing hydrogenated oils to the discussion. We frequently ingest hydrogenated oils through baked goods, packaged snacks, lunch meats, canned foods, and more.

To read part two of this post go here.