Fats, briefly defined, are organic compounds made up of carbon, hydrogen, and oxygen. Based on mass, fats provide more energy than carbohydrates or proteins. Fats are put under a broader umbrella of substances called lipids. Fat can be either a liquid or a solid. All fats are combinations of saturated and unsaturated fatty acids.
Unsaturated fat is usually liquid at refrigerator temperatures. Monounsaturated and polyunsaturated fat are two kinds of unsaturated fat. Monounsaturated fat is found in large amounts in foods from plants, including olive oil, peanut, avocado, and canola oil (from rapeseed). It is a slightly unsaturated fat. Polyunsaturated fat is highly unsaturated fat that is found in large amounts in foods from plants, including safflower, sunflower, corn, and soybean oil. Unsaturated fats are not thought to raise blood cholesterol and may actually lower levels.
You may be curious what differentiates this good type of fat (unsaturated) from the bad—it’s because of hydrogen. The bonds that hold together unsaturated fats have double bonds—chemical bonds that share electrons. Saturated fats have more hydrogen atoms and no double bonds. Unsaturated fats can be made more saturated by adding hydrogen atoms. This process is called hydrogenation. You may have seen the phrase “partially hydrogenated oils”. This is usually seen on butter and means that the company has taken an unsaturated fat and made it more like a saturated fat. This process hardens the fat. Recall that unsaturated fat is usually in liquid form.
Linoleic is an essential fatty acid and is needed for proper nerve function. It can be found at your grocery store in canola oil. Alpha-linoleic acid is also necessary; it’s a precursory substance that the body changes to another acid. It ultimately gets converted into a substance found in fish oils. So, the expression “eating fish makes you smarter” has some truth.
Polyunsaturated fats have the potential to generate free radicals, especially when exposed to heat or sunlight. For your future reference, keep vegetable oils stored out of direct sunlight. Mono-unsaturated olive oil is less likely to generate free radicals and is a better choice for salads. Peanut oil is also mono-unsaturated and will withstand much higher heat before breaking down, thus, it is a better choice for cooking.
For further details, I recommend these pages on Wikipedia about fatty acids:
- Stearic Acid - fully saturated
- Oleic Acid - monounsaturated
- Linoleic Acid - polyunsaturated
Write a Comment