Cooking oil

Cooking oil is plant, animal, or synthetic fat used in frying, baking, and other types of cooking. It is also used in food preparation and flavouring that doesn't involve heat, such as salad dressings and bread dips, and in this sense might be more accurately termed edible oil.

Cooking oil is typically a liquid at room temperature, although some oils that contain saturated fat, such as coconut oil, palm oil and palm kernel oil are solid.[1]

Types of cooking oil include: olive oil, palm oil, soybean oil, canola oil (rapeseed oil), pumpkin seed oil, corn oil, sunflower oil, safflower oil, peanut oil, grape seed oil, sesame oil, argan oil, rice bran oil and other vegetable oils, as well as animal-based oils like butter and lard.

Oil can be flavoured with aromatic foodstuffs such as herbs, chillies or garlic.

Health and nutrition

Olive oil
Italian olive oil
Sunflower seed oil

The appropriate amount of fat as a component of daily food consumption is a topic of some controversy. Some fat is required in the diet, and fat (in the form of oil) is also essential in many types of cooking. The FDA recommends that 30% or fewer of calories consumed daily should be from fat.[2] Other nutritionists recommend that no more than 10% of a person's daily calories come from fat.[3] In extremely cold environments, a diet that is up to two-thirds fat is acceptable and can, in fact, be critical to survival.

While consumption of small amounts of saturated fats is essential, initial meta-analyses (1997, 2003) found a high correlation between high consumption of such fats and LDL concentration[4] and other risk markers of coronary heart disease.[5] More recent meta-analyses (2009, 2010), based on cohort studies and on controlled, randomized trials, find a positive[6] or neutral[7] effect from shifting consumption from carbohydrate to saturated fats as a source of calories, and only a modest advantage for shifting from saturated to polyunsaturated fats (10% lower risk for 5% replacement).[7]

Mayo Clinic has highlighted oils that are high in saturated fats, including coconut, palm oil and palm kernel oil. Those of lower amounts of saturated fats, and higher levels of unsaturated (preferably monounsaturated) fats like olive oil, peanut oil, canola oil, avocado, safflower, corn, sunflower, soy, mustard and cottonseed oils are generally healthier.[8] The National Heart, Lung and Blood Institute[9] and World Heart Federation[10] have urged saturated fats be replaced with polyunsaturated and monounsaturated fats. The health body lists olive and canola oils as sources of monounsaturated oils while soybean and sunflower oils are rich with polyunsaturated fat. Results of research carried out in Costa Rica in 2005 suggest that consumption of non-hydrogenated unsaturated oils like soybean and sunflower are preferable to the consumption of palm oil.[11]

Not all saturated fats have negative effects on cholesterol.[12] Some studies indicate that Palmitic acid in palm oil does not behave like other saturated fats, and is neutral on cholesterol levels because it is equally distributed among the three "arms" of the triglyceride molecule.[13] Further, it has been reported that palm oil consumption reduces blood cholesterol in comparison with other traditional sources of saturated fats such as coconut oil, dairy and animal fats.[14]

Saturated fat is required by the body and brain to function properly. In fact, one study in Brazil compared the effects of soybean oil to coconut oil (a highly saturated fat) and found that while both groups showed a drop in BMI, the soybean oil group showed an increase in overall cholesterol (including a drop in HDL, the good cholesterol). The coconut oil group actually showed an increase in the HDL:LDL ratio (meaning there was more of the good cholesterol), as well as smaller waist sizes (something that was not shown in the soybean oil group).[15]

In 2007, scientists Kenneth C. Hayes and Pramod Khosla of Brandeis University and Wayne State University indicated that the focus of current research has shifted from saturated fats to individual fats and percentage of fatty acids (saturates, monounsaturates, polyunsaturates) in the diet. An adequate intake of both polyunsaturated and saturated fats is needed for the ideal LDL/HDL ratio in blood, as both contribute to the regulatory balance in lipoprotein metabolism.[16]

Oils high in unsaturated fats may help to lower "bad" LDL cholesterol and may also raise "good" HDL cholesterol, though these effects are still under study.

Peanut, cashew, and other nut-based oils may also present a hazard to persons with a nut allergy. A severe allergic reaction may cause anaphylactic shock and result in death.

Trans fats

Unlike other dietary fats, trans fats are not essential, and they do not promote good health.[17] The consumption of trans fats increases one's risk of coronary heart disease[18] by raising levels of "bad" LDL cholesterol and lowering levels of "good" HDL cholesterol.[19] Trans fats from partially hydrogenated oils are more harmful than naturally occurring oils.[20]

Several large studies[21][22][23][24] indicate a link between consumption of high amounts of trans fat and coronary heart disease and possibly some other diseases. The United States Food and Drug Administration (FDA), the National Heart, Lung and Blood Institute and the American Heart Association (AHA) all have recommended limiting the intake of trans fats.

Cooking with oil

Heating an oil changes its characteristics. Oils that are healthy at room temperature can become unhealthy when heated above certain temperatures. When choosing a cooking oil, it is important to match the oil's heat tolerance with the cooking method.[25]

Palm oil contains more saturated fats than canola oil, corn oil, linseed oil, soybean oil, safflower oil, and sunflower oil. Therefore, palm oil can withstand the high heat of deep frying and is resistant to oxidation compared to highly unsaturated vegetable oils.[26] Since about 1900, palm oil has been increasingly incorporated into food by the global commercial food industry because it remains stable in deep frying or in baking at very high temperatures[27][28] and for its high levels of natural antioxidants.[29]

Oils that are suitable for high-temperature frying (above 230 °C or 446 °F) because of their high smoke point

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. To delay the development of rancid oil, a blanket of an inert gas, usually nitrogen, is applied to the vapor space in the storage container immediately after production. This is referred to as tank blanketing. Vitamin E oil is a natural antioxidant that can also be added to cooking oils to prevent rancidification.

All oils should be kept in a cool, dry place. Oils may thicken, but they will soon return to liquid if they stand at room temperature. To prevent negative effects of heat and light, oils should be removed from cold storage just long enough for use. Refined oils high in monounsaturated fats keep up to a year (olive oil will keep up to a few years), while those high in polyunsaturated fats keep about six months. Extra-virgin and virgin olive oils keep at least 9 months after opening. Other monounsaturated oils keep well up to eight months, while unrefined polyunsaturated oils will keep only about half as long.

In contrast, saturated oils, such as coconut oil and palm oil, have much longer shelf lives and can be safely stored at room temperature.[31] Their lack of polyunsaturated content causes them to be more stable.[32]

Types of oils and their characteristics

Lighter, more refined oils tend to have a higher smoke point. Experience using an oil is generally a sufficiently reliable guide. Although outcomes of empirical tests are sensitive to the qualities of particular samples (brand, composition, refinement, process), the data below should be helpful in comparing the properties of different oils.

Smoking oil indicates a risk of combustion, and left unchecked can also set off a fire alarm. When using any cooking oil, should it begin to smoke, reduce the heat immediately. The cook should be fully prepared to extinguish a burning oil fire before beginning to heat the oil, by having on hand the lid to place on the pan, or (for the worst case) having on hand the proper fire extinguisher.

Type of oil or fat Saturated Monounsaturated Polyunsaturated Smoke point
[note 1]		 Uses
Almond 8% 66% 26% 221 °C (430 °F) Baking, sauces, flavoring
Avocado oil 12% 74% 14% 271 °C (520 °F) Frying, sautéing, dipping oil, salad oil
Butter 66% 30% 4% 150 °C (302 °F) Cooking, baking, condiment, sauces, flavoring
Ghee, clarified butter 65% 32% 3% 190–250 °C (374–482 °F) Deep frying, cooking, sautéing, condiment, flavoring
Canola oil 6% 62% 32% 204 °C (399 °F) Frying, baking, salad dressings
Coconut oil, (virgin) 92% 6% 2% 177 °C (351 °F) Commercial baked goods, candy and sweets, whipped toppings, nondairy coffee creamers, shortening
Rice bran oil 20% 47% 33% 254 °C (489 °F) Cooking, frying, deep frying, salads, dressings. Very clean flavoured & palatable.
Corn oil 13% 25% 62% 236 °C (457 °F) Frying, baking, salad dressings, margarine, shortening
Cottonseed oil 24% 26% 50% 216 °C (421 °F) Margarine, shortening, salad dressings, commercially fried products
Flaxseed oil (Linseed oil)[35] 11% 21% 68% 107 °C (225 °F)[36] Salad dressings, nutritional supplement
Grape seed oil 12% 17% 71% 204 °C (399 °F) Cooking, salad dressings, margarine
Hemp oil 9% 12% 79% 165 °C (329 °F) Cooking, salad dressings
Lard 41% 47% 2% 138–201 °C (280–394 °F) Baking, frying
Margarine, hard 80% 14% 6% 150 °C (302 °F)[note 2] Cooking, baking, condiment
Mustard oil 13% 60% 21% 254 °C (489 °F) Cooking, frying, deep frying, salads, dressings. Very clean flavoured & palatable.
Margarine, soft 20% 47% 33% 150–160 °C (302–320 °F) Cooking, baking, condiment
Macadamia oil 12.5% 84% 3.5% 210 °C (410 °F) Cooking, frying, deep frying, salads, dressings. A slightly nutty odour.
Diacylglycerol (DAG) oil 3.05% 37.95% 59% 215 °C (419 °F) Frying, baking, salad oil
Olive oil (extra virgin) 14% 73% 11% 190 °C (374 °F) Cooking, salad oils, margarine
Olive oil (virgin) 14% 73% 11% 215 °C (419 °F) Cooking, salad oils, margarine
Olive oil (refined) 14% 73% 11% 225 °C (437 °F) Sautee, stir frying, deep frying, cooking, salad oils, margarine
Olive oil (extra light) 14% 73% 11% 242 °C (468 °F) Sautee, stir frying, frying, deep frying, cooking, salad oils, margarine
Palm oil 52% 38% 10% 230 °C (446 °F) Cooking, flavoring, vegetable oil, shortening
Peanut oil / groundnut oil 18% 49% 33% 231 °C (448 °F) Frying, cooking, salad oils, margarine
Pumpkin seed oil 8% 36% 57% 121 °C (250 °F) salad oils
Safflower oil 10% 13% 77% 265 °C (509 °F) Cooking, salad dressings, margarine
Sesame oil (Unrefined) 14% 43% 43% 177 °C (351 °F) Cooking
Sesame oil (semi-refined) 14% 43% 43% 232 °C (450 °F) Cooking, deep frying
Soybean oil 15% 24% 61% 241 °C (466 °F) Cooking, salad dressings, vegetable oil, margarine, shortening
Sunflower oil (linoleic) 11% 20% 69% 246 °C (475 °F) Cooking, salad dressings, margarine, shortening
Sunflower oil (high oleic)[37] 9% 82% 9% 160 °C (320 °F) Cooking
Tea seed oil[38] 22% 60% 18% 252 °C (486 °F) Cooking, salad dressings, stir frying, frying, margarine
Walnut oil (Semi-refined) 9% 23% 63% 204 °C (399 °F)[39] Salad dressings, added to cold dishes to enhance flavor

Cooking oil extraction and refinement

Olive oil production in Croatia

Cooking oil extraction and refinement are separate processes. Extraction first removes the oil, typically from a seed, nut or fruit. Refinement then alters the appearance, texture, taste, smell, or stability of the oil to meet buyer expectations.

Extraction

There are three broad types of oil extraction:

In large-scale industrial oil extraction you will often see some combination of pressing, chemical extraction and/or centrifuging in order to extract the maximum amount of oil possible.[45]

Refinement

Cooking oil can either be unrefined, or refined using one or more of the following refinement processes (in any combination):

Filtering, a non-chemical process which screens out larger particles, could be considered a step in refinement, although it doesn't alter the state of the oil.

Most large-scale commercial cooking oil refinement will involve all of these steps in order to achieve a product that's uniform in taste, smell and appearance, and has a longer shelf life.[45] Cooking oil intended for the health food market will often be unrefined, which can result in a less stable product but minimizes exposure to high temperatures and chemical processing.

Waste cooking oil

A bin for spent cooking oil in Austin, Texas, USA, managed by a recycling company.

Proper disposal of used cooking oil is an important waste-management concern. Oil is lighter than water and tends to spread into thin and broad membranes which hinder the oxygenation of water. Because of this, a single litre of oil can contaminate as much as 1 million litres of water. Also, oil can congeal on pipes provoking blockages.[46]

Because of this, cooking oil should never be dumped in the kitchen sink or in the toilet bowl. The proper way to dispose of oil is to put it in a sealed non-recyclable container and discard it with regular garbage.[47] Placing the container of oil in the refrigerator to harden also makes disposal easier and less messy.

Recycling

Cooking oil can be recycled. It can be used as animal feed, directly as fuel, and to produce biodiesel,[48] soap, and other industrial products.

In the recycling industry, used cooking oil recovered from restaurants and food-processing industries (typically from deep fryers or griddles) is called recycled vegetable oil (RVO), used vegetable oil (UVO), waste vegetable oil (WVO), or yellow grease.[49]

Yellow grease is used to feed livestock, and to make soap, make-up, clothes, rubber, detergents, and biodiesel fuel.[50][51]

Used cooking oil, besides being converted to biodiesel, can be used directly in modified diesel engines and for heating.

Grease traps or interceptors collect fats and oils from kitchen sinks and floor drains which would othewise clog sewer lines and interfere with septic systems and sewage treatment. The collected product is called brown grease in the recycling industry.[49] Brown grease is contaminated with rotted food solids and considered unsuitable for re-use in most applications.

Gutter oil or Trench Oil are terms used in Asia for recycled oil which is processed to resemble virgin oil but contains toxic contaminents and is illegally sold for cooking; its origin is frequently brown grease from garbage.[52]

Notes

  1. ↑ The smoke point of an oil depends primarily on its free fatty acid content (FFA) and molecular weight. Through repeated use, as in a deep fryer, the oil accumulates food residues or by-products of the cooking process, that lower its smoke point further. The values shown in the table must therefore be taken as approximate, and are not suitable for accurate or scientific use.[33][34]
  2. ↑ 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.

References

  1. ↑ "Dietary fats explained". Retrieved May 4, 2012.
  2. ↑ "The Food Pyramid". FDA Consumer. Archived from dead link] the original on 2006-08-22. Retrieved 2006-09-18.
  3. ↑ Dean Ornish, MD, Lifestyle Program
  4. ↑ Clarke, R; Frost, C; Collins, R; Appleby, P; Peto, R (1997). "Dietary lipids and blood cholesterol: quantitative meta-analysis of metabolic ward studies". BMJ 314 (7074): 112–7. doi:10.1136/bmj.314.7074.112. PMC 2125600. PMID 9006469.
  5. ↑ Mensink, RP; Zock, PL; Kester, AD; Katan, MB (2003). "Effects of dietary fatty acids and carbohydrates on the ratio of serum total to HDL cholesterol and on serum lipids and apolipoproteins: a meta-analysis of 60 controlled trials". The American journal of clinical nutrition 77 (5): 1146–55. PMID 12716665.
  6. ↑ Jakobsen, M. U; O'Reilly, E. J; Heitmann, B. L; Pereira, M. A; Balter, K.; Fraser, G. E; Goldbourt, U.; Hallmans, G. et al. (2009). "Major types of dietary fat and risk of coronary heart disease: a pooled analysis of 11 cohort studies". American Journal of Clinical Nutrition 89 (5): 1425–32. doi:10.3945/ajcn.2008.27124. PMC 2676998. PMID 19211817.
  7. ↑ 7.0 7.1 Katan, Martijn B.; Mozaffarian, Dariush; Micha, Renata; Wallace, Sarah (2010). Katan, Martijn B., ed. "Effects on Coronary Heart Disease of Increasing Polyunsaturated Fat in Place of Saturated Fat: A Systematic Review and Meta-Analysis of Randomized Controlled Trials". PLoS Medicine 7 (3): e1000252. doi:10.1371/journal.pmed.1000252. PMC 2843598. PMID 20351774.
  8. ↑ Dietary fats: Know which types to choose Mayo Clinic website
  9. ↑ Choose foods low in saturated fat National Heart, Lung, and Blood Institute (NHLBI), NIH Publication No. 97-4064. 1997.
  10. ↑ Diet & cardiovascular disease World Heart Federation website
  11. ↑ Kabagambe, Baylin, Ascherio & Campos, EK; Baylin, A; Ascherio, A; Campos, H (November 2005). "The Type of Oil Used for Cooking Is Associated with the Risk of Nonfatal Acute Myocardial Infarction in Costa Rica". Journal of Nutrition (135 ed.) 135 (11): 2674–2679. PMID 16251629.
  12. ↑ Ng, TK; Hassan, K; Lim, JB; Lye, MS; Ishak, R (1991). "Nonhypercholesterolemic effects of a palm-oil diet in Malaysian volunteers". American Journal of Clinical Nutrition 53 (4): 1015S–1020S. PMID 2012009.
  13. ↑ A critical review of the cholesterolemic effects of palm oil Tony Ng Kock Wai, The United Nations University Press, Food and Nutrition Bulletin, Volume 15 (1993/1994), Number 2, June 1994
  14. ↑ Chong, YH; Ng, TK (1991). "Effects of palm oil on cardiovascular risk". The Medical journal of Malaysia 46 (1): 41–50. PMID 1836037.
  15. ↑ Assunção, Monica L.; Ferreira, Haroldo S.; Dos Santos, Aldenir F.; Cabral, Cyro R.; Florêncio, Telma M. M. T. (2009). "Effects of Dietary Coconut Oil on the Biochemical and Anthropometric Profiles of Women Presenting Abdominal Obesity". Lipids 44 (7): 593–601. doi:10.1007/s11745-009-3306-6. PMID 19437058.
  16. ↑ Hayes, Kenneth; Khosla, Pramod (2007). "The complex interplay of palm oil fatty acids on blood lipids". European Journal of Lipid Science and Technology 109 (4): 453–464. doi:10.1002/ejlt.200700005.
  17. ↑ Food and nutrition board, institute of medicine of the national academies (2005). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients). National Academies Press. p. 423. ISBN 0-309-08537-3.
  18. ↑ Food and nutrition board, institute of medicine of the national academies (2005). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients). National Academies Press. p. 504. ISBN 0-309-08537-3.
  19. ↑ "Trans fat: Avoid this cholesterol double whammy". Mayo Foundation for Medical Education and Research (MFMER). Retrieved 2007-12-10.
  20. ↑ Mozaffarian, Dariush; Katan, Martijn B.; Ascherio, Alberto; Stampfer, Meir J.; Willett, Walter C. (2006). "Trans Fatty Acids and Cardiovascular Disease". New England Journal of Medicine 354 (15): 1601–113. doi:10.1056/NEJMra054035. PMID 16611951.
  21. ↑ Willett, WC; Stampfer, MJ; Manson, JE; Colditz, GA; Speizer, FE; Rosner, BA; Sampson, LA; Hennekens, CH (1993). "Intake of trans fatty acids and risk of coronary heart disease among women". Lancet 341 (8845): 581–5. doi:10.1016/0140-6736(93)90350-P. PMID 8094827.
  22. ↑ Hu, Frank B.; Stampfer, Meir J.; Manson, Joann E.; Rimm, Eric; Colditz, Graham A.; Rosner, Bernard A.; Hennekens, Charles H.; Willett, Walter C. (1997). "Dietary Fat Intake and the Risk of Coronary Heart Disease in Women". New England Journal of Medicine 337 (21): 1491–9. doi:10.1056/NEJM199711203372102. PMID 9366580.
  23. ↑ Hayakawa, Kyoko; Linko, Yu-Yen; Linko, Pekka (2000). "The role of trans fatty acids in human nutrition". Starch - Stärke 52 (6–7): 229–35. doi:10.1002/1521-379X(200007)52:6/7<229::AID-STAR229>3.0.CO;2-G.
  24. ↑ The Nurses' Health Study (NHS)
  25. ↑ Orna Izakson. "Oil right: choose wisely for heart-healthy cooking - Eating Right". E: the Environmental Magazine.
  26. ↑ De Marco, Elena; Savarese, Maria; Parisini, Cristina; Battimo, Ilaria; Falco, Salvatore; Sacchi, Raffaele (2007). "Frying performance of a sunflower/palm oil blend in comparison with pure palm oil". European Journal of Lipid Science and Technology 109 (3): 237–246. doi:10.1002/ejlt.200600192.
  27. ↑ Che Man, YB; Liu, J.L.; Jamilah, B.; Rahman, R. Abdul (1999). "Quality changes of RBD palm olein, soybean oil and their blends during deep-fat frying". Journal of Food Lipids 6 (3): 181–193. doi:10.1111/j.1745-4522.1999.tb00142.x.
  28. ↑ Matthäus, Bertrand (2007). "Use of palm oil for frying in comparison with other high-stability oils". European Journal of Lipid Science and Technology 109 (4): 400–409. doi:10.1002/ejlt.200600294.
  29. ↑ Sundram, K; Sambanthamurthi, R; Tan, YA (2003). "Palm fruit chemistry and nutrition" (PDF). Asia Pacific journal of clinical nutrition 12 (3): 355–62. PMID 14506001.
  30. ↑ "Smoke Points of Various Fats - Kitchen Notes - Cooking For Engineers". cookingforengineers.com. 2012. Retrieved July 3, 2012.
  31. ↑ Coconutoil.com
  32. ↑ Articledashboard.com
  33. ↑ F. D. Gunstone; D. Rousseau (2004). Rapeseed and canola oil: production, processing, properties and uses. Oxford: Blackwell Publishing Ltd. p. 91. ISBN 0-8493-2364-9. Retrieved 2011-01-17.
  34. ↑ Brown, Amy L. (2010). Understanding Food: Principles and Preparation. Belmont, CA: Wadsworth Publishing. p. 468. ISBN 0-538-73498-1. Retrieved 2011-01-16.
  35. ↑ A. G. Vereshagin and G. V. Novitskaya (1965) The triglyceride composition of linseed oil. Journal of the American Oil Chemists' Society 42, 970-974.
  36. ↑ http://www.goodeatsfanpage.com/collectedinfo/oilsmokepoints.htm
  37. ↑ Sunflowernsa.com
  38. ↑ "Triglyceride composition of tea seed oil". doi:10.1002/jsfa.2740271206.
  39. ↑ "Cooking Oil Smoke Points". Retrieved January 3, 2011.
  40. ↑ nutritiondata.com → Oil, vegetable, sunflower Retrieved on September 27, 2010
  41. ↑ USDA → Basic Report: 04042, Oil, peanut, salad or cooking Retrieved on January 16, 2015
  42. ↑ nutritiondata.com → Egg, yolk, raw, fresh Retrieved on August 24, 2009
  43. ↑ "09038, Avocados, raw, California". National Nutrient Database for Standard Reference, Release 26. United States Department of Agriculture, Agricultural Research Service. Retrieved 14 August 2014.
  44. ↑ "Feinberg School > Nutrition > Nutrition Fact Sheet: Lipids". Northwestern University. Archived from the original on 2011-07-20.
  45. ↑ 45.0 45.1 "How cooking oil is made". Retrieved May 18, 2012.
  46. ↑ "Tips to avoid water waste and to require the preservation of hydro-resources". Natureba - Educação Ambiental. Retrieved 2007-09-05.
  47. ↑ "Grease Disposal Tips to Help the City's Environment". NYC Department of Environmental Protection. Retrieved 2007-08-05.
  48. ↑ "Production of biodiesel based on waste oils and/or waste fats from biogenic origin for use as fuel" (PDF). CDM - Executive Board. Retrieved 2007-09-05.
  49. ↑ 49.0 49.1 Brown Grease Feedstocks for Biodiesel. K. Shaine Tyson, National Renewable Energy Laboratory. Available from Northeast Regional Biomass Program. Retrieved January 31, 2009
  50. ↑ Murphy, Denis J. Plant lipids: biology, utilisation, and manipulation. Wiley-Blackwell, 2005, p. 117.
  51. ↑ Radich, Anthony Biodiesel Performance, Costs, and Use
  52. ↑ Austin Ramzy, China Cracks Down on "Gutter Oil," a Substance Even Worse Than its Name, Time, 13 September 2011.

Further reading

External links

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