I recenly bought
Natural foods;: Eat better, live longer, improve your sex life
at the local used book warehouse. The book so fare has been very informative with information about food and nutrients as well as why the body needs nutrients and what foods have them in abundance.
Wendy Pritzker, author, also includes some literature from Organic Merchants of Los Angeles, CA that informs the natural shopper about oils, called The Oil Story by Ezra Hendon.
In The Oil Story, the three ways of extracting vegetable oils from nuts, grains, beans, seeds, or olives.
First is by hydrolic press, an ancient and best method. Only olives and sesame seeds can be pressed without being cooked first and they are the only ones that can be truely considered cold pressed.
Secod is expeller pressed. "This used a screw or continuous press with a constantly rotating worm shaft. Cooked material goes in one end and is put under continuous pressure until discharged at the other end with oil squeezed out." (Lowdown on Edible Oils)
The last methos is solvent extraction, which is dangerous as it used petroleum based solvents to extract the oils from the plant. This method is universally used by big oil companies because it gets the oils out faster and cheaper.
The terms like "cold pressed" and "virgin" are meaningless in most cases as there is no legal definition adn mean whatever the manufacturer wants them to mean.
So how do you tell if the oil you are buy is crude, cold pressed, and unrefined if the label isn't always truthful?
Buy from a trusted consumer. Make sure your local health food market is legit by asking questions about their products.
Buy trust products. Research brands and companies to see exactly how they make their oils and foods.
Buy local when you can, talk to the manufacturer, even take a tour through the factory if possible.
It all comes down to educating yourself about what it is you are putting in your body.