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 not involving 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]

There are a wide variety of cooking oils from plant sources such as olive oil, palm oil, soybean oil, canola oil (rapeseed oil), corn oil, peanut 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
Sunflower seed oil

The appropriate amount of fat as a component of daily food consumption is established as a guideline by regulatory agencies such as the FDA which recommends that 10% or fewer of calories consumed daily should be from saturated fat and 20-35% of total daily calories come from polyunsaturated and monounsaturated fats.[2]

While consumption of small amounts of saturated fats is common in diets,[3] meta-analyses found a significant correlation between high consumption of saturated fats and blood LDL concentration,[4] a risk factor for cardiovascular diseases.[5] Other meta-analyses based on cohort studies and on controlled, randomized trials found a positive[6] or neutral[7] effect from shifting consumption from saturated fats 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 having lower amounts of saturated fats and higher levels of unsaturated (preferably monounsaturated) fats like olive oil, peanut oil, canola oil, soy and cottonseed oils are generally healthier.[8] The US National Heart, Lung and Blood Institute[9] urged saturated fats be replaced with polyunsaturated and monounsaturated fats, listing olive and canola oils as sources of healthier monounsaturated oils while soybean and sunflower oils as good sources of polyunsaturated fats. One study showed that consumption of non-hydrogenated unsaturated oils like soybean and sunflower are preferable to the consumption of palm oil for lowering the risk of heart disease.[10]

Peanut, cashew and other nut-based oils may present a hazard to persons with a nut allergy.

Trans fats

Unlike other dietary fats, trans fats are not essential, and they do not promote good health.[11] The consumption of trans fats increases one's risk of coronary heart disease[12] by raising levels of "bad" LDL cholesterol and lowering levels of "good" HDL cholesterol.[13] Trans fats from partially hydrogenated oils are more harmful than naturally occurring oils.[14]

Several large studies[15][16][17][18] 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.[19]

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.[20] 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[21][22] and for its high levels of natural antioxidants.[23]

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

Storing and keeping oil

All oils degrade in response to heat, light, and oxygen.[25] To delay the development of rancidity, a blanket of an inert gas, usually nitrogen, is applied to the vapor space in the storage container immediately after production, a process called tank blanketing.

In a cool, dry place, oils have greater stability, but may thicken, although they will soon return to liquid if they stand at room temperature. To minimize the degrading effects of heat and light, oils should be removed from cold storage just long enough for use. Refined oils high in monounsaturated fats, such as macadamia oil,[25] keep up to a year, while those high in polyunsaturated fats keep about six months. Rancidity tests show that the life of walnut oil is about 3 months, a period considerably shorter than the "best before" duration shown on labels.[25]

In contrast, saturated oils, such as avocado oil, have relatively long shelf lives and can be safely stored at room temperature, as their lower polyunsaturated content facilitates stability.[25]

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 Omega-3 Omega-6 Smoke point
[note 1]		 Uses
Almond 8% 66% 26% 0 17% 221 °C (430 °F) Baking, sauces, flavoring
Avocado oil 12% 74% 14% 0.95% 12% 271 °C (520 °F) Frying, sautéing, dipping oil, salad oil
Butter 66% 30% 4% 0.3% 2.7% 150 °C (302 °F) Cooking, baking, condiment, sauces, flavoring
Ghee, clarified butter 65% 32% 3% 0 0 190–250 °C (374–482 °F) Deep frying, cooking, sautéing, condiment, flavoring
Canola oil 6% 62% 32% 9.1% 18% 204 °C (399 °F) Frying, baking, salad dressings
Coconut oil, (virgin) 92% 6% 2% 0 1.8% 177 °C (351 °F) Cooking, tropical cuisine, beauty products
Rice bran oil 20% 47% 33% 1.6% 33% 254 °C (489 °F) Cooking, frying, deep frying, salads, dressings. Very clean flavoured & palatable.
Corn oil 13% 25% 62% 1.1% 53% 236 °C (457 °F) Frying, baking, salad dressings, margarine, shortening
Cottonseed oil 24% 26% 50% 0.2% 50% 216 °C (421 °F) Margarine, shortening, salad dressings, commercially fried products
Flaxseed oil (Linseed oil)[28] 11% 21% 68% 53% 13% 107 °C (225 °F)[29] Salad dressings, nutritional supplement
Grapeseed oil 12% 17% 71% 0.1% 69% 204 °C (399 °F) Cooking, salad dressings, margarine
Hemp oil 9% 12% 79% 18% 55% 165 °C (329 °F) Cooking, salad dressings
Lard 41% 47% 2% 1% 10% 138–201 °C (280–394 °F) Baking, frying
Margarine, hard 80% 14% 6% 2% 22% 150 °C (302 °F)[note 2] Cooking, baking, condiment
Mustard oil 13% 60% 21% 5.9% 15% 254 °C (489 °F) Cooking, frying, deep frying, salads, dressings. Very clean flavoured & palatable.
Margarine, soft 20% 47% 33% 2.4% 23% 150–160 °C (302–320 °F) Cooking, baking, condiment
Macadamia oil 12.5% 84% 3.5% 0 2.8% 210 °C (410 °F) Cooking, frying, deep frying, salads, dressings. A slightly nutty odour.
Diacylglycerol (DAG) oil 3.05% 37.95% 59% 0 - 215 °C (419 °F) Frying, baking, salad oil
Olive oil (extra virgin) 14% 73% 11% 0.7% 9.8% 190 °C (374 °F) Cooking, salad oils, margarine
Olive oil (virgin) 14% 73% 11% 0.7% 9.8% 215 °C (419 °F) Cooking, salad oils, margarine
Olive oil (refined) 14% 73% 11% 0 0 225 °C (437 °F) Sautee, stir frying, deep frying, cooking, salad oils, margarine
Olive oil (extra light) 14% 73% 11% 0 0 242 °C (468 °F) Sautee, stir frying, frying, deep frying, cooking, salad oils, margarine
Palm oil 52% 38% 10% 0.2% 9.1% 230 °C (446 °F) Cooking, flavoring, vegetable oil, shortening
Peanut oil / groundnut oil 18% 49% 33% 0 31% 231 °C (448 °F) Frying, cooking, salad oils, margarine
Pumpkin seed oil 8% 36% 57% 0% 64% 121 °C (250 °F) salad oils
Safflower oil 10% 13% 77% 0 74% 265 °C (509 °F) Cooking, salad dressings, margarine
Sesame oil (Unrefined) 14% 43% 43% 0.3 41% 177 °C (351 °F) Cooking
Sesame oil (semi-refined) 14% 43% 43% 0.3 41% 232 °C (450 °F) Cooking, deep frying
Soybean oil 15% 24% 61% 6.7% 50% 241 °C (466 °F) Cooking, salad dressings, vegetable oil, margarine, shortening
Sunflower oil (linoleic, refined) 11% 20% 69% 0% 56% 246 °C (475 °F) Cooking, salad dressings, margarine, shortening
Sunflower oil (high oleic, refined)[30] 9% 82% 9% 0.2% 3.6% 225 °C (437 °F) Cooking
Tea seed oil[31] 22% 60% 18% 0.7% 22% 252 °C (486 °F) Cooking, salad dressings, stir frying, frying, margarine
Walnut oil (Semi-refined) 9% 23% 63% 10% 53% 204 °C (399 °F)[32] 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.[38]

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.[38] 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.[39]

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.[40] 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,[41] 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.[42]

Yellow grease is used to feed livestock, and to make soap, make-up, clothes, rubber, detergents, and biodiesel fuel.[43][44]

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.[42] 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.[45]

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.[26][27]
  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. ↑ "Dietary Guidelines for Americans 2005; Key Recommendations for the General Population". US Department of Health and Human Services and Department of Agriculture. 2005.
  3. ↑ Yanai H, Katsuyama H, Hamasaki H, Abe S, Tada N, Sako A (2015). "Effects of Dietary Fat Intake on HDL Metabolism". J Clin Med Res 7 (3): 145–9. doi:10.14740/jocmr2030w. PMC 4285059. PMID 25584098.
  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". Am J Clin Nutr 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. 1 2 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 Staff. 2015.
  9. ↑ "Choose foods low in saturated fat". National Heart, Lung, and Blood Institute (NHLBI), NIH Publication No. 97-4064. 1997.
  10. ↑ 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.
  11. ↑ 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.
  12. ↑ 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.
  13. ↑ "Trans fat: Avoid this cholesterol double whammy". Mayo Foundation for Medical Education and Research (MFMER). Retrieved 2007-12-10.
  14. ↑ 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.
  15. ↑ 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.
  16. ↑ 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.
  17. ↑ 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.
  18. ↑ The Nurses' Health Study (NHS)
  19. ↑ Orna Izakson. "Oil right: choose wisely for heart-healthy cooking - Eating Right". E: the Environmental Magazine.
  20. ↑ 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.
  21. ↑ 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.
  22. ↑ 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.
  23. ↑ 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.
  24. ↑ "Smoke Points of Various Fats - Kitchen Notes - Cooking For Engineers". cookingforengineers.com. 2012. Retrieved July 3, 2012.
  25. 1 2 3 4 Kochhar, S. Parkash; Henry, C. Jeya K. (2009-01-01). "Oxidative stability and shelf-life evaluation of selected culinary oils". International Journal of Food Sciences and Nutrition. 60 Suppl 7: 289–296. doi:10.1080/09637480903103774. ISSN 1465-3478. PMID 19634067.
  26. ↑ 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.
  27. ↑ Brown, Amy L. (2010). Understanding Food: Principles and Preparation. Belmont, CA: Wadsworth Publishing. p. 468. ISBN 0-538-73498-1. Retrieved 2011-01-16.
  28. ↑ A. G. Vereshagin and G. V. Novitskaya (1965) The triglyceride composition of linseed oil. Journal of the American Oil Chemists' Society 42, 970-974.
  29. ↑ http://www.goodeatsfanpage.com/collectedinfo/oilsmokepoints.htm
  30. ↑ Sunflowernsa.com
  31. ↑ "Triglyceride composition of tea seed oil". doi:10.1002/jsfa.2740271206.
  32. ↑ "Cooking Oil Smoke Points". Retrieved January 3, 2011.
  33. ↑ nutritiondata.com → Oil, vegetable, sunflower Retrieved on September 27, 2010
  34. ↑ USDA → Basic Report: 04042, Oil, peanut, salad or cooking Retrieved on January 16, 2015
  35. ↑ nutritiondata.com → Egg, yolk, raw, fresh Retrieved on August 24, 2009
  36. ↑ "09038, Avocados, raw, California". National Nutrient Database for Standard Reference, Release 26. United States Department of Agriculture, Agricultural Research Service. Retrieved 14 August 2014.
  37. ↑ "Feinberg School > Nutrition > Nutrition Fact Sheet: Lipids". Northwestern University. Archived from the original on 2011-07-20.
  38. 1 2 "How cooking oil is made". Retrieved May 18, 2012.
  39. ↑ "Tips to avoid water waste and to require the preservation of hydro-resources". Natureba - Educação Ambiental. Retrieved 2007-09-05.
  40. ↑ "Grease Disposal Tips to Help the City's Environment". NYC Department of Environmental Protection. Retrieved 2007-08-05.
  41. ↑ "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.
  42. 1 2 Brown Grease Feedstocks for Biodiesel. K. Shaine Tyson, National Renewable Energy Laboratory. Available from Northeast Regional Biomass Program. Retrieved January 31, 2009
  43. ↑ Murphy, Denis J. Plant lipids: biology, utilisation, and manipulation. Wiley-Blackwell, 2005, p. 117.
  44. ↑ Radich, Anthony Biodiesel Performance, Costs, and Use
  45. ↑ Austin Ramzy, China Cracks Down on "Gutter Oil," a Substance Even Worse Than its Name, Time, 13 September 2011.

Further reading

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