Description and Cultivation
There are thirty different bush-like species of cotton, differing from one another in terms of shape, colour and size (varying in height between 1 and 2 m). The cotton plant has one-year cycle and is modest in its requirements when it comes to soil. It is sensitive to frost, however, needing much sun and heat. The temperature should be between 25 and 27 C during the growth period.
As the flowering and maturity extend over a period of several months, harvesting must be carried out at frequent intervals. After drying the seeds are separated from the fibres by specially designed rollers.
Unlike many other oil plants the oil is not the most important product of the cotton plant, but merely a by-product. For 4500 years, cotton was cultivated solely for its fibres since these could be spun into yarn. The seeds were considered worthless and discarded. The oil did not come into use until some 100years ago, the first cotton plantations being cultivated in India.
The cotton bush is cultivated on all five continents, the most important regions being China, India, the USA and Pakistan. The major exporting countries of cottonseed oil are the USA and Argentina.
The extraction of cottonseed oil on a larger scale did not begin until the end of the 19th century, when machinery was designed to separate the cotton fibres from the seeds.
Around 70 % of the harvest consists of seeds containing 20 % fat. Pressing and extraction yield the red-black, viscous cottonseed oil, which is then filtered, purified and refined. The press residue produces a protein-rich cake used as supplementary feed. Crude cottonseed oil contains gossypol, a phenolic substance, which needs to be removed in the refining process.
Cottonseed oil is a liquid oil with a high content of linoleic acid. In comparison with other liquid oils it has a high content of saturated fatty acids. Refined cottonseed oil is used in a wide variety of food applications.