Cooking oil

Plant oils
Olive oil
Types
Vegetable fats	(list)
Macerated	(list)
Uses
Drying oil - Oil paint
Cooking oil
Fuel - Biodiesel
Components
Saturated fat
Monounsaturated fat
Polyunsaturated fat
Trans fat

Cooking oil is purified fat of plant origin, which is usually liquid at room temperature (Saturated oils such as coconut and palm are more solid at room tempurature than other oils).

Some of the many different kinds of edible vegetable oils include: olive oil, palm oil, soybean oil, canola oil, pumpkin seed oil, corn oil, sunflower oil, safflower oil, peanut oil, grape seed 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, corn, soybean or sunflower oils.

Oil can be flavored by immersing aromatic food stuffs such as fresh herbs, peppers, garlic and so forth in the oil for a period of time. However, care must be taken when storing flavored oils to prevent the growth of Clostridium botulinum (the bacteria that produces toxins that can lead to botulism).

Health and nutrition

The appropriate amount of fat as a component of daily food consumption is the 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 less of calories consumed daily should be from fat.^[1] Other nutritionists recommend that no more than 10% of a person's daily calories come from fat.^[2] 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, meta-studies conducted by several scientists find high corelation between excessive amounts of such fats and coronary heart disease.^[3][4] Mayo Clinic highlighted oils that are high in saturated fats include 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, avocados, safflower, corn, sunflower, soy and cottonseed oils are generally healthier.^[5] The National Heart, Lung and Blood Institute^[6] and World Heart Federation^[7] have urged saturated fats be replaced with polyunsaturated and monounsaturated fats. The health body lists olive and canola oils as sources of monosaturated oils while soybean and sunflower oils are rich with polyunsaturated fat. A 2005 research in Costa Rica suggests consumption of non-hydrogenated unsaturated oils like soybean and sunflower over palm oil.^[8]

The labelling of the cholesterol content of foods on the basis of their total saturated fats content is unjustified because not all saturated fats are equally cholesterolemic.^[9] 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.^[10] Studies have indicated that palm oil consumption reduces blood cholesterol in comparison with other traditional sources of saturated fats such as coconut oil, dairy and animal fats.^[11]

In 2007, scientists Kenneth C. Hayes and Pramod Khosla of Brandeis University and Wayne State University indicated research focus has shifted from saturated fats to individual and total composite of fatty acids (saturates, monounsaturates, polyunsaturates) that comprise our daily fat intake. 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.^[12]

Olive oil's high oleic fatty acids raises "good" HDL cholesterol, a heart-healthy effect that need not be limited by an arbitrary figure.

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.^[13] The consumption of trans fats increases one's risk of coronary heart disease^[14] by raising levels of "bad" LDL cholesterol and lowering levels of "good" HDL cholesterol.^[15] Trans fats from partially hydrogenated oils are more harmful than naturally occurring oils.^[16]

Several large studies^{[17][18][19][20]} 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 people to limit intake of trans-fat.

Cooking with oils

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.^[21]

A 2001 parallel review of 20-year dietary fat studies in the United Kingdom, the United States of America and Spain^[22] concluded that polyunsaturated oils like soya, canola, sunflower and corn degrade easily to toxic compounds when heated up. Prolonged consumption of burnt oils lead to atherosclerosis, inflammatory joint disease and development of birth defects. The scientists also questioned global health authories’ wilful recommendation of large amounts of polyunsaturated fats into the human diet without accompanying measures to ensure the protection of these fatty acids against heat-and oxidative-degradation.

Palm oil contains more saturated fats then canola oil, corn oil, linseed oil, soybean oil, safflower oil, and sunflower oil. Therefore, palm oil can withstand extreme deepfry heat and resistant to oxidation compared to vegetable oils of high unsaturated fats.^[23] Since the turn of the century, palm oil is increasingly incorporated into the global commercial food industry because it remains stable when deepfried or baked in extreme high heat^[24][25] and for its high levels of natural antioxidants.^[26]

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

• Canola oil (marketed as "rapeseed oil" or, sometimes, simply "vegetable oil" in the UK)
• Corn oil
• Mustard oil
• Olive oil, pomace
• Olive oil, extra light
• Palm oil
• Peanut oil (marketed as "groundnut oil" in the UK)
• Rice bran oil
• Safflower oil
• Sesame oil (semi-refined)
• Soybean oil
• Sunflower oil

Oils suitable for medium-temperature frying (above 190 °C/374 °F) include:

• Almond oil
• Ghee, Clarified Butter
• Cottonseed oil
• Grape seed oil
• Lard
• Diacylglycerol (DAG) oil
• Olive oil (Virgin, and refined)
• Walnut oil

Unrefined oils should not be used for frying, but are safe for simmering.

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.

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 (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 a high eight months; unrefined polyunsaturated oils only about half as long.

In contrast, saturated oils such as coconut and palm have much longer shelf lives and can be safely stored at room temperature. ^[27] This is due to their lack of polyunsaturated content. ^[28]

Types of oils and their characteristics

This section needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (May 2008)

Lighter, more refined oils tend to have higher smoke points. 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, heat should be reduced immediately. Generally, one should be fully prepared to extinguish a burning oil fire before heating, typically by having on hand the lid to place on the pan, or (for the worst case) having on hand the proper fire extinguisher.

Comparison to other types of food

Fat composition in different foods (click at right to hide or show)

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Food	Saturated	Monounsaturated	Polyunsaturated
	As weight percent (%) of total fat
Cooking oils
Canola oil	7	59	29
Corn oil	13	24	59
Olive oil	13	74	8
Soybean oil	15	24	58
Dairy Products
Cheese,regular	64	29	3
Cheese,light	60	30	0
Milk, whole	62	28	4
Milk, 2%	62	30	0
Ice cream, gourmet	62	29	4
Ice cream, light	62	29	4
Meats
Beef	33	38	5
Ground sirloin	38	44	4
Pork chop	35	44	8
Ham	35	49	16
Chicken breast	29	34	21
Chicken	34	23	30
Turkey breast	30	20	30
Turkey drumstick	32	22	30
Fish,orange roughy	23	15	46
Salmon	28	33	28
Hot dog, beef	42	48	5
Hot dog, turkey	28	40	22
Burger, fast food	36	44	6
Cheeseburger, fast food	43	40	7
Breaded chicken sandwich	20	39	32
Grilled chicken sandwich	26	42	20
Sausage, Polish	37	46	11
Sausage, turkey	28	40	22
Pizza, sausage	41	32	20
Pizza, cheese	60	28	5
Nuts
Almonds dry roasted	9	65	1
Cashews dry roasted	20	59	17
Macadamia dry roasted	15	79	2
Peanuts dry roasted	14	50	31
Pecans dry roasted	8	62	25
Flaxseeds, ground	8	23	65
Sesame seeds	14	38	44
Soybeans	14	22	57
Sunflower seeds	11	19	66
Walnuts dry roasted	9	23	63
Sweets and baked goods
Candy, chocolate bar	59	33	3
Candy, fruit chews	14	44	38
Cookie, oatmeal raisin	22	47	27
Cookie, chocolate chip	35	42	18
Cake, yellow	60	25	10
Pastry, Danish	50	31	14
Fats added during cooking or at the table
Butter, stick	63	29	3
Butter, whipped	62	29	4
Margarine, stick	18	39	39
Margarine, tub	16	33	49
Margarine, light tub	19	46	33
Lard	39	45	11
Shortening	25	45	26
Chicken fat	30	45	21
Beef fat	41	43	3
Dressing, blue cheese	16	54	25
Dressing, light Italian	14	24	58
Other
Egg yolk fat	36[32]	44[32]	16[32]
Unless else specified in boxes, then reference is: [33]

Waste cooking oil

A bin for spent cooking oil in Austin, Texas

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^{[citation needed]}. Also, oil can congeal on pipes provoking blockages.^[34]

Because of this, cooking oil should never be dumped on 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.^[35]

Cooking oil can be recycled. It can be used to produce soap and biodiesel.^[36]

Notes and References

Other references

• O'Brien, R.D. (1998). Fats and Oils: Formulating and Processing for Applications. Technomic Publishing Co., Inc.. 
• Potter, N.N. and J.H. Hotchkiss (1995). Food Science - Fifth Edition. Chapman & Hall. pp. 359–80, 402–7. 

See also

Wikimedia Commons has media related to: Cooking oils

Wikibooks Cookbook has a recipe/module on Oil and fat

Food portal

• Cooking spray
• Vegetable fats and oils

External links

• American Oil Chemical Society official website
• Foil Oil Smoke Points from the Canola Council
• Review of Nutritional Attributes of Cold Pressed Hemp Seed Oil from King's College London
• Algae: Another way to grow edible oils