Deodorization animal fats

In the following study the conversion of non-refined palm oil, waste cooking oil, animal fats, deodorizer distillate, and soap stocks into biodiesel will be reported. Finally, the direct use of animal fat for the production of electricity will be discussed. 

Animal fats are subjected to deodorization when a very bland or essentially flavorless fat is desired, such as in margarines or cooking fats. The fats are heated at 200°C to 260°C in the absence of air (to prevent oxidation) and treated with dry steam under a vacuum of 5-10 milliatmospheres. Off-flavor compounds are volatile under these conditions and are captured and removed in the steam stream. In addition to flavor components, free fatty acids, which can also contribute undesirable flavors, and other minor constituents such as peroxides, sterols, sterol esters, toco-pherols, and other natural antioxidants are partially or completely removed from the fat by this treatment. 

Trace metals are present in crude vegetable oils at parts per million (ppm) levels. Researchers have shown that soybean oil flavor can deteriorate from autoxidation, even at an iron content as low as 0.3 ppm (26) in the deodorized oil. Metal initiators initiate autoxidation in all vegetable oils and animal fats. 

Typically the last step in the edible oil refinery is deodorization, and this process is included in almost every refining operation, regardless of the other unit operations selected. While in the past limited natural fats could be utilized as edible products (such as butter and animal fats), most oils used today come from sources having natural components that if not removed impart objectionable flavors and tastes. These oils contain not only flavor bodies that must be eliminated to produce a palatable product but other unit operations, such as hydrogenation, impart a negative flavor and color that must be removed in the deodorizer. Shelf life and color are also important considerations upon which the deodorizer has a direct impact. 

Sterols Soybean oil (deodorizer distillates) contains a considerable amount of - phytosterols (sito- and stigmasterol) and -asteroids, which are isolated and used in pharmaceuticals. Animal fats contain cholesterol, which can be recovered from the distillation residues of fatty acids. Properties and origin ... 

Soaps are used in virtually every household every day. Basic soap is produced by the saponification (hydrolysis with sodium hydroxide) of animal or vegetable fats and has little toxicity. Soaps commonly used, however, contain additives to give them deodorant and antimicrobial properties. Such soaps may contain chloroxylenol, phenol, triclosan, methylisothiazolinone (MIT), and other toxicants that are released into water streams)40 ... 

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