Description
Coconut oil, also known as coconut butter, is a vegetable oil extracted from copra (the dried inner flesh of coconuts) with many applications.
Physical properties
Coconut oil is a fat consisting of about 90% saturated fat. The oil contains predominantly triglycerides with 86.5% saturated fatty acids, 5.8% monounsaturated fatty acids, and 1.8% polyunsaturated fatty acids. Of the saturated fatty acids, coconut oil is primarily 44.6% lauric acid, 16.8% myristic acid and 8.2% palmitic acid, although it contains seven different saturated fatty acids in total. Its only monounsaturated fatty acid is oleic acid while its only polyunsaturated fatty acid is linoleic acid.
Unrefined coconut oil melts at 20-25 °C and smokes at 170 °C (350 °F)., while refined coconut oil has a higher smoke point of 232 °C (450 °F).
Coconut oil has a long shelf life compared to other oils, lasting up to two years due to its resilience to high temperatures. Coconut oil is best stored in solid form – i.e. at temperatures lower than 24.5 °C (76°F) in order to extend shelf life. However, unlike most oils, coconut oil will not be damaged by warmer temperatures.
Chemical properties
Among the most stable of all vegetable oils, coconut oil is slow to oxidize and thus resistant to rancidity.
Types of oil available
Unrefined oil
Otherwise known as raw oil, this is oil that has been obtained simply through mechanical pressing and without further treatment apart from (possibly) filtration. Raw oil retains the compounds that provide its distinctive taste and smell. For marketing purposes, raw oil may also be called “extra virgin”.
Raw oil is extracted by crushing and pressing copra. Traditionally, the oil was obtained by grating or grinding copra, then boiling it in water.
Refined oil
Various treatments can be given to the raw oil to produce different products each with their own characteristics and hence applications. Refined oil is virtually tasteless and odourless.
Hydrogenated oil
Hydrogenated coconut oil may either be fully or partially hydrogenated.
Fractionated oil
Fractionated coconut oil” is a fraction of the whole oil, in which most of the long-chain triglycerides are removed so that only saturated fats remain. It may also referred to as “caprylic/capric triglyceride” or “MCT oil” because mostly the medium-chain triglycerides caprylic andcapric acid) are left in the oil.
Because it is completely saturated, fractionated oil is even more heat stable than other forms of coconut oil and has a nearly indefinite shelf life.
Research on health effects
During the 1980’s, The American Heart Association issued statements indicating that coconut oil’s high saturated fat content was detrimental to cardiovascular health and promoted heart disease . A research study at the Heart Research Institute in Sydney, Australia used coconut oil and safflower oil (high in polyunsaturated fat) in two otherwise identical meals for the study’s participants . The study found the following:
“…three hours after eating the coconut oil meal, the lining of the arteries was hindered from expanding to increase blood flow. After six hours, the anti-inflammatory qualities of the good cholesterol were reduced.
“…the safflower oil meal seemed to improve those anti-inflammatory qualities. Also, fewer inflammatory agents were found in the arteries than before the meal.”
The above study involved only 14 subjects, and it is unclear how the coconut oil used for the study was processed. The conclusion that coconut oil is unhealthy is consistent with prior concerns raised by the AHA.
The study has been criticised as misleading. The participants in the study consumed refined coconut oil, which is regarded by some as dangerous because of the added chemicals to make the oil colorless and odorless. In contrast to the study done by the AHA, a more recent modern study [ ] showed coconut oil reducing LDL and improving HDL.
Furthermore, a study done by the Lazaro Hospital showed that coconut oil reduced the viral load on HIV patients. 15 participants were involved in the study and 7 of them showed substantial improvement after consuming coconut oil daily for six months. [ ] However, the study could have produced better results if the participants consumed more coconut oil.
Participants in the study who consumed more coconut oil lowered their viral loads quicker than those who consumed less coconut oil. Furthermore, there have been instances where people have consumed as much as 1 cup of coconut oil a day and have lowered their viral loads to undetectable amounts.[ ]
Applications
Cooking
Coconut oil is commonly used in cooking, especially when frying, and it has a high smoke point temperature which makes it good for this purpose. In communities where coconut oil is widely used in cooking, the refined oil is the one most commonly used.
Coconut oil is often used in making a curry.
In Malaysia, coconut oil is used for making Nasi Lemak.
Manufacturing
Coconut oil is used in volume quantities for making margarine, soap and cosmetics.
Hydrogenated or partially-hydrogenated coconut oil is often used in non-dairy creamers, and snack foods.
Fractionated coconut oil is also used in the manufacture of essences, [massage]] oils and cosmetics
Cosmetics and skin treatments
Coconut oil is excellent as a skin moisturiser. A study shows that extra virgin coconut oil is as effective and safe as mineral oil when used as a moisturiser, with absence of adverse reactions .
Coconut oil can also help in healing Keratosis pilaris by moisturising the affected area. The coconut oil should be applied in the shower, and may cause the KP bumps to disappear.
In India and Sri Lanka, coconut oil is commonly used for styling hair, and cooling or soothing the head (stress relief).
As a fuel
Traditional use
Coconut oil is used in oil lamps.
In diesel engines
Coconut oil has been tested for use as a feedstock for biodiesel to be used as a diesel engine fuel. In this manner it can be applied to power generation and transport using diesel engines.
Coconut oil is blended to make biodiesel but can also be used straight, without blending. However, only blends with 10% or less of coconut oil can be safely used in unmodified engines. The oil needs to meet the Weihenstephan standard for pure vegetable oil used as a fuel since otherwise moderate to severe damage from coking and clogging will occur in an unmodified engine . Stationary engines that are continuously loaded (>70%) may possibly be used without engine modifications but there is divergent opinion about this.
The physical constraints of using raw coconut oil in a diesel engine are formed by:
- higher viscosity of coconut oil (up to 10 times as high as diesel), leading to altered spray pattern of injected fuel, additional stress on injection pump
- minimum combustion chamber temperature of 500 °C to avoid polymerisation of the fuel, leading to clogged injectors, sticking piston rings and lubrication oil deterioration
- solidification point between 22-25 °C requires an additional fuel tank heater in temperate climates.
Raw coconut oil can be used as a fuel for generating electricity by remote communities that have an abundant supply of coconuts and milling capacity, provided diesel engines are adapted.
Coconut oil is currently used as a fuel for transport and electricity generation in the Philippines and India while research is being carried out in the islands of the Pacific .
