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| Coconut oil |
Coconut oil is an edible oil extracted from the kernel or meat of matured coconut harvested from the coconut palm (Cocos nucifera). Throughout the tropical world it has provided the primary source of fat in the diets of millions of people for generations. It has various applications in food, medicine, and industry. Coconut oil is very heat stable so is suited to methods of cooking at high temperatures like frying. Because of its stability it is slow to oxidize and thus resistant to rancidity, lasting up to two years due to high saturated fat content. Numerous governmental agencies and medical organizations recommend against the consumption of significant amounts of coconut oil due to the high saturated fat content.
Coconut oil can be extracted through "dry" or "wet" processing. Dry processing requires the meat to to be extracted from the shell and dried using fire, sunlight or kilns to create copra. The copra is pressed or dissolved with solvents, producing the coconut oil and a high protein, high fiber mash. The mash is of poor quality for human consumption and is instead fed to ruminants; there is no process to extract the protein from the mash. The preparation and storage of copra often occurs in unhygienic conditions which results in a poor quality oil that requires refining before consumption. A considerable portion of the oil extracted from copra is lost due to spoilage, consumption by insects and rodents, and during the extraction process. All "wet" process involves raw coconut rather than dried copra, using the protein in the coconut to create an emulsion of the oil and water. The more problematic step is breaking up the emulsion to recover the oil. Originally this was done through lengthy boiling, but this produces a discolored oil and is not economical; modern techniques uses centrifuges and various pre-treatments including cold, heat, acids, salts, enzymes, electrolysis, shock waves, or some combination of them. Despite numerous variations and technologies, wet processing is less viable than dry processing due to a 10-15% lower yield, even compared to the losses due to spoilage and pests with dry processing. Wet processes also requires an expensive investment of equipment and energy, incurring high capital and operating costs.
Proper harvesting of the coconut (the age of a coconut can be 2 to 20 months when picked) makes a significant difference in the efficacy of the oil making process and the use of a centrifuge process makes the best final extracted product. Copra made from immature nuts is more difficult to work with and produces an inferior product with lower yields. Conventional coconut oil uses hexane to extract up to 10% more oil than just using rotary mills and expellers. The oil is then refined to remove certain free fatty acids, in order to reduce susceptibility rancidification. Other processes to increase shelf life include using copra with a moisture content below 6%, keeping the moisture content of the oil below 0.2%, heating the oil to 130–150 °C (266–302 °F) and adding salt or citric acid. Virgin coconut oil (VCO) can be produced from fresh coconut meat, milk or residue. Producing it from the fresh meat involves removing the shell and washing, then either wet-milling or drying the residue and using a screw press to extract the oil. VCO can also be extracted from fresh meat by grating and drying it to a moisture content of 10-12%, then using a manual press to extract the oil. Producing it from coconut milk involves grating the coconut and mixing it with water, then squeezing out the oil. The milk can also be fermented for 36-48 hours, the oil removed and the cream heated to remove any remaining oil. A third option involves using a centrifuge to separate the oil from the other liquids. Coconut oil can also be extracted from the dry residue left over from the production of coconut milk.
A thousand mature coconuts weighing approximately 8,640 kilograms (19,000 lb) yields around 170 kilograms (370 lb) of copra from which around 70 litres (15 imp gal) of coconut oil can be extracted.
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