The all-wet process uses coconut milk extracted from raw coconut rather than dried copra. The proteins in the coconut milk create an emulsion of oil and water. The more problematic step is breaking up the emulsion to recover the oil. This used to be done by prolonged boiling, but this produces a discolored oil and is not economical. Modern techniques use centrifuges and pre-treatments including cold, heat, acids, salts, enzymes, electrolysis, shock waves, steam distillation, or some combination thereof.
Despite numerous variations and technologies, wet processing is less viable than dry processing due to a 10–15% lower yield, even taking into account the losses due to spoilage and pests with dry processing. Wet processes also require 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. Copra made from immature nuts is more difficult to work with and produces an inferior product with lower yields.
Refined, bleached, and deodorized (RBD) oil is usually made from copra, dried coconut kernel, which is pressed in a heated hydraulic press to extract the oil. This yields practically all the oil present, amounting to more than 60% of the dry weight of the coconut. This crude coconut oil is not suitable for consumption because it contains contaminants and must be refined with further heating and filtering.
Fractionated coconut oil provides fractions of the whole oil so that its different fatty acids can be separated for specific uses. Lauric acid, a 12-carbon chain fatty acid, is often removed because of its high value for industrial and medical purposes.The fractionation of coconut oil can also be used to isolate caprylic acid and capric acid, which are medium-chain triglycerides, as these are used for medical applications, special diets and cosmetics, sometimes also being used as a carrier oil for fragrances.
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