Cooking oil
| Plant oils |
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| Types |
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Cooking oil is purified fat of plant or animal origin, which is liquid at room temperature.
Some of the many different kinds of edible vegetable oils include: palm oil, olive oil, soybean oil, canola oil, corn oil, sunflower oil, safflower oil, peanut oil, grape seed oil, cashew oil, sesame oil, argan oil and rice bran oil. Many other kinds of vegetable oils are also used for cooking.
The generic term "vegetable oil" when used to label a cooking oil product refers to a blend of a variety of oils often based on palm oil, corn, soybean or sunflower oils.
Oil can be flavoured by immersing aromatic food stuffs such as fresh herbs, peppers and so forth in the oil for an extended period of time. However, care must be taken when using garlic and onions to prevent the growth of Clostridium botulinum (the bacterium which causes botulism) in this medium.
Health and nutrition
Fats are an essential nutrient in the human diet, but an unbalanced diet is not healthy. For most individuals, it is appropriate to get 30% of one's daily food energy from fats and oils, evenly divided between monounsaturated, polyunsaturated, and saturated fats.[1]
Cooking oil is a special problem, as hydrogenation of oils makes them more stable, but also creates trans fats, only found in hydrogenated oils, which are increasingly thought to be unhealthy.
Some hydrogenation of oils occurs during cooking, causing normally healthy unsaturated fats like olive oil to convert to trans fats. But in non-industrial settings this process does not occur at appreciable quantities.[2]
Many cooking oils are known sources of various vitamins (A and E), minerals, amino acids, essential fatty acids, and antioxidants.
Peanut and cashew oils and nut-based oils may present a hazard to persons with a nut allergy. A severe allergic reaction may cause anaphylactic shock and result in death.
Storing and keeping oil
Whether refined or not, all oils are sensitive to heat, light and exposure to oxygen. Rancid oil has an unpleasant aroma and acrid taste, and its nutrient value is greatly diminished.
It is best to store all oils in the refrigerator or a cool, dry place. Oils may thicken, but if you let them stand at room temperature they will soon return to liquid. To prevent negative effects of heat and light, take oils out of cold storage just long enough to use them. Refined oils high in monounsaturated fats keep up to a year, while those high in polyunsaturated fats keep about six months. Extra-virgin and virgin olive oils keep about a year after opening. Olive and other monounsaturated oils keep well up to eight months; unrefined polyunsaturated oils only about half as long. Some comparisons have been made to vegetable oil relating to it's biomass.
Types of oils and their characteristics
Saturated fats are unhealthy in excess, but the consumption of small amounts of these oils is essential. Unsaturated fats (monounsaturated, polyunsaturated) are generally healthier for those consuming Western-style diets. Nutrition experts recommend that no more than 30% of a Western-style diet be composed of fats. In extremely cold environments, a diet that is up to two-thirds fat is acceptable and can, in fact, be critical to survival in that type of environment.
| Type of Oil or Fat | Saturated fat | Monounsaturated fat | polyunsaturated | Smoke Point[3] | Uses |
|---|---|---|---|---|---|
| Butter | 66% | 30% | 4% | 150 °C (302 °F) | cooking, baking, condiment, sauces, flavoring |
| Ghee, clarified butter | 65% | 32% | 3% | 190 °C (374 °F) | deep frying, cooking, sauteing, condiment, flavoring |
| Canola oil | 6% | 62% | 32% | 238 °C (460 °F) | frying, baking, salad dressings |
| Coconut oil | 92% | 6% | 2% | 177 °C (350 °F) | commercial baked goods, candy and sweets, whipped toppings, nondairy coffee creamers, shortening |
| Corn oil | 13% | 25% | 62% | 236 °C (457 °F) | frying, baking, salad dressings, margarine, shortening |
| Cottonseed oil | 24% | 26% | 50% | 216 °C (420 °F) | margarine, shortening, salad dressings, commercially fried products |
| Grape seed oil | 12% | 17% | 71% | 204 °C (400 °F) | cooking, salad dressings, margarine |
| Lard | 41% | 47% | 12% | 138-201 °C (280-395 °F)[4] | baking, frying |
| Margarine, hard | 80% | 14% | 16% | 150-160 °C (300-320 °F)[3] | cooking, baking, condiment |
| Margarine, soft | 20% | 47% | 33% | 150-160 °C (300-320 °F) | cooking, baking, condiment |
| Olive oil | 14% | 77% | 9% | 190 °C (375 °F) | frying, cooking, salad dressings, condiment |
| Palm oil | 52% | 38% | 10% | 230 °C (446 °F) | cooking, flavoring, vegetable oil, shortening |
| Peanut oil | 18% | 49% | 33% | 231 °C (448 °F) | frying, cooking, salad oils, margarine |
| Safflower oil | 10% | 13% | 77% | 265 °C (509 °F) | cooking, salad dressings, margarine |
| Soybean oil | 15% | 24% | 61% | 241 °C (466 °F) | cooking, salad dressings, vegetable oil, margarine, shortening |
| Sunflower oil | 11% | 20% | 69% | 246 °C (475 °F) | cooking, salad dressings, margarine, shortening |
There is a general lack of consensus on the smoke points of many popular oils, as well as a lack of standardization for qualifiers such as "refined". Empirical tests are heavily dependent on the qualities of the particular samples (brand, composition, process) available, but appear to be the major source of available data. In the field, experience trumps references, and there is no source that seems truly authoritative. A crude guide is that lighter, more refined oils have higher smoke points. If there is any doubt at all, be fully prepared to extinguish a burning oil fire before heating.
Notes and References
- ^ FDA Consumer The Food Pyramid Retrieved September 18, 2006
- ^ Olive Oil Source Cooking with Olive Oil Retrieved December 12, 2006
- ^ a b The smoke point of margarine varies depending on the types of oils used in its formulation, but can be generally assumed to be similar to that of butter.
- ^ The smoke point of oils depends primarily on their free fatty acid content (FFA) and molecular weight. Through repeated use, as in a deep fryer, food residues or by-products of the cooking process will accumulate within the oil and lower its smoke point. The values shown in the above table must therefore be taken as approximate, and are not suitable for accurate or scientific use.
Other references
- O'Brien, R.D. (1998). Fats and Oils: Formulating and Processing for Applications. Lancaster, PA: Technomic Publishing Co., Inc.
- Potter, N.N. and J.H. Hotchkiss (1995). Food Science - Fifth Edition. New York: Chapman & Hall. pp. 359-80, 402-7.
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