Buying cooking oil used to be an easy task. You walked into the grocery store, went down the baking aisle, and pulled a bottle from the shelf. There were no options; there was no confusion.Today, entire aisles are devoted to cooking oil. Oil can come from just about anything, like avocados, almonds, and soybeans. And to add to the confusion, you can get oil flavored with anything from chili peppers to rosemary to lemon.How do you know which oil is best for your sizzling vegetable stir-fry, perfect pumpkin muffins, or savory balsamic salad dressing? Getting to know a little bit about oil will help you decide which oil is right for your cooking project.
Oil From Just About Anything
Oil can be made from a variety of sources, such as:
- Seeds: safflower, sesame, sunflower, seeds from canola plant
- Nuts: almond, walnut
- Grains: corn
- Beans: peanut, soy
- Fruits: avocado, olive, coconut
The first step in processing is to remove the oil from the seed, nut, grain, bean, or fruit. The extraction process can be chemical or mechanical. When done chemically, the oil source is soaked in a petroleum compound, usually hexane. The oil then requires further refining to remove this toxic solvent. This method is efficient, provides a high yield, and is more common than mechanical extraction.Mechanical pressing, also called expeller-pressed, uses no chemicals. The oil is derived from its source by squeezing it in a mechanical press. The process can raise the temperature of the oil. Cold pressed means that no additional external heat is added during the processing. Oil purists believe that unrefined, cold pressed oil retains the most flavor, aroma, color, and nutrients.
Understanding Oil's Structure
In order to know which oil to choose, it is important to understand a little bit about the chemistry of oil. Oil is made up of fatty acids. A fatty acid is a chain of carbon atoms. Every carbon on the chain has places that hydrogen atoms can fill. If each carbon on the chain has all the available slots filled with hydrogen atoms, it is a saturated fatty acid (SFA). If the fatty acid chain is not holding all the hydrogen that it can, it is considered unsaturated. When there is one point of unsaturation, the fatty acid is considered monounsaturated (MUFA). If there are two or more points of unsaturation, the fatty acid is polyunsaturated (PUFA). Specially modified margarine-like fatty acids are known as trans fats.Saturated fats raise total blood cholesterol, as well as LDL (“bad”) cholesterol. However, they also may raise levels of HDL (“good”) cholesterol. In contrast, monounsaturated and certain polyunsaturated fats may improve most or all aspects of cholesterol profile. Trans fats, on the other hand, worsen most aspects of cholesterol profile and should be avoided.