Cottonseed oil refining

The world s cotton farmers produce around 34 million tonnes of cottonseed annually in addition to the fibre. Cottonseed is used as an animal feed and, in the form of cottonseed oil, as a common cooking product accounting for approximately 8% of the world s vegetable oil consumption. Data compiled by FAO/WHO show the potential for pesticides to contaminate both refined cottonseed oil and cottonseed derivatives fed to animals. 

A typical analysis of refined cottonseed oil indicates the composition of the acids present as glycerides to be as follows linoleic acid 39.3% oleic acid 33.1% palmitic acid 19.1% stearic acid 1.9% arachidic acid 0.6%, andmyristic acid 0.3%. Also present are small quantities of phospholipid, phytosterols, and pigments. The toxic polyphenolic pigment gossypol is present in raw cottonseed and in the oil cake remaining after expression of oil it is not found in the refined oil. 

Edible fats and oils vary considerably in the chemical composition which determines those physical characteristics that provide functionality. Physical, chemical, and performance analyses are the tools available to the fats and oils processor for the evaluation of existing products, development of new products, purchase of raw materials, and identification of specific customer requirements. Typical refined cottonseed oil analytical characteristics including fatty acid and triacylglycerol composition and ranges allowing for the different varieties, growing conditions, and analytical error are shown in Tables 7.1, 7.2 and 7.3. 

Table 7.1 Typical refined cottonseed oil analytical characteristics...

The tocopherols in crude cottonseed oil (Table 3.40), as with other oils, are partially removed during refining. This, together with the removal of gossypol and related phenolic compounds with antioxidant activity, is possibly the reason for cottonseed oil s relatively poor oxidative stability compared to groundnut oil but this is probably only part of the explanation. Refined cottonseed oils still contain 74-94 mg/kg of tocopherols. 

Fig. 2.14. The system propane-oleic acid-refined cottonseed oil. Trans. Am. Inst. Chem. Engrs. 38, 891 (1942)]...

Let us now take a specific example of the procedure. The official method is as follows a. Refined Oil, Use only 1 yellow glass, 35 yellow for refined cottonseed oil and refined peanut oil, 70 yellow for refined soybean oil. Use not more than 2 red glasses up to and including 13.0 red, and not more than 3 red glasses above 13.0 red. ... 

Experiments were carried out using soybean oil, canola oil, refined com oil, refined cottonseed oil, refined sunflower oil, refined palm oil, and refined coconut oil obtained from commercial sources. Biobased lubricant oils used in this study are given in table 14.1. 

Chem. Descrip. Distilled monoglyceride from refined cottonseed oil CAS 8029-44-5 EINECS/ELINCS 232-438-5... 

In processing most oilseeds, hexane is stripped from the miscella by distillation to produce a crude oil that subsequently is alkali or physically refined. However, gossy-pol and other pigments become extremely difficult to bleach if left in warm cottonseed oil for more than a few days. It is normal practice for cottonseed oil mills to send their crude oil immediately to an alkali refinery or to operate an on-site miscella refinery, where phosphatides, FFA, and color pigments are removed by alkali treatment of the oil-extraction solvent mixture. Cooling the crude oil as produced, until refining, also slows fixing of color. 

Mid-1980s—Degummed, alkali-refined cottonseed and soybean oils used in pesticide aerial spays. 

Cottonseed Oil (Unhydrogenated) occurs as a dark red-brown oil. It is obtained from the seed of the cotton plant Gossypium hirsutum (American) or Gossypium barbadense (Egyptian) by mechanical expression or solvent extraction. It is refined, bleached, and deodorized to substantially remove free fatty acids, phospholipids, color, odor and flavor components, and miscellaneous other non-oil materials. It is liquid at 21° to 27°, clouds at 21°, and partially solidifies at storage temperatures... 

Separation equipment which solved a major oil extraction problem Eliminated illumination and lubrication as potential cottonseed oil applications Color adsorbed with Fuller s earth Alkali refining introduced and accepted European import tariffs imposed with complete expulsion from Italian markets Limited acceptance due to flavor odor Allowed the addition of higher levels of cottonseed oil to lard U.S. label restrictions—mandatory identification of lard compound ... 

Figure 1. Relationship between free fatty acid content and smoke, flash, and fire points of cottonseed and peanut oils.----------, Refined cottonseed oii --------, peanut oil.

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