Alkali-refining

Cotton linter was purified by Kier boiling and then bleached with the 4-stage bleaching method, namely, chlorination, hot alkali-refining, hypochlorite and chlorine dioxide steps. 

Hydrolyzed vegetable oil (HVO) or acid oil is a by-product of alkali refining of crude corn oil, and is obtained by acidulating alkaline soapstock. HVO must contain at least 92% total fatty acids. It is used to control dust and as an energy source in beef and poultry rations. 

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

The manufacture of fatty acids from triglycerides via their reaction with alkali followed by acidification is not used commercially. However, the recovery of fatty acids from alkali refining of fats/oils (to produce acid soaps) and soap reboiling operations (the recovery of fatty acids from the acidification of soap waste streams) are practiced still in special situations, for example, in edible oils refining where soap-stock that is generated from chemical (alkali) refining requires acidulation to produce acid oils with commercial value. 

The recovery of fatty acids from soapstocks by a continuous process has been described soapstocks obtained from degumming and alkali refining operations are subjected to a saponification step followed by controlled acidification for cost efficiency and pollution control.Ila,b... 

Tallow occurs as an off white fat. It is obtained by heat rendering of tissues (cuttings and trimmings) from beef and, to a lesser degree, mutton shortly after slaughter. Rendered Tallow may be alkali refined and bleached, or bleached and deodorized without prior refining. It is a firm fat containing... 

Rendered, alkali-refined, and bleached-deodorized Tallows are white to off white solids at 21° to 21°. Alkali-refined and bleached-deodorized Tallows, which are pale yellow to colorless and free of extraneous matter at 54°, differ from rendered Tallow, which is clear to hazy and may contain extraneous matter. 

Rendered Tallow Alkali-Refined Tallow Bleached and Deodorized Tallow... 

Hot alkali refined, 10% NaOH, 120°C. This value includes the amount of... 

In the most recent development, acid and aqueous sodium hydroxide, rather than acid and water are being used, especially with lower quality oils (acid-caustic degumming). This represents an intermediate between acid-water degumming and alkali refining. It obviates the need for cooling, similar to the practice in alkali refining. Phosphoric acid rather than an organic acid is preferred in this case. Phosphatides as well as some of the other impurities are removed, and if sufficient, alkali is applied to saponify the free fatty acids, fully refined oil is obtained. 

TABLE 16. Bleached Canola ON After Alkali Refining or Acid Degumming. 

Characteristic Alkali Refined/Bleached Acid Degummed/Bleached... 

Another approach is to make use of the fact that in contact with alkali, chlorophyll derivatives also react to form a precipitate (88). This can be used in the course of alkali refining. The precipitate can be removed together with the aqueous soap phase, but at this time, specihc details are still proprietary. Experience so far has shown that as much as about 70% of the chlorophyll derivatives can be removed in the course of alkah refining. 

Alkali Refining This involves the determination of free fatty acids, phosphorus, and, if desired, chlorophyll, before and after the process. In addition, soap concentration is determined after water washing. Soap determination can present some difficulty in establishing the endpoint of the titration with oils high in chlorophylls, because of the dark color of such oils. 

USA-ASTM standard for 100% pure biodiesel is similar in many respects (146), but it is written for the use of soybean oil as the main starting material. Canola oil for methyl ester production must either be degummed (<20 mg/kg of phosphorus), or in addition, must be alkali refined and bleached, depending on the methyl ester production process requirements (148). 

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 ... 

Refining of crude Linola oil by conventional steps, namely, degumming, alkali refining, bleaching, and deodorization, produces colorless and odorless oil, which has good oxidative stability (9). In addition, properties of crude and refined, bleached, and deodorized (RED) Linola oil are comparable with other commodity oils (Table 1). 

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