Fatty acids distillation

Fig. 1. Fatty acid distillation sequence (a) sequence generated by ranked heuristics and (b) more expensive direct sequence.

In the fatty acid distillation process, wastewater is generated as a result of an acidification process, which breaks the emulsion. This wastewater is neutralized and sent to the sewer. It will contain salt from the neutralization, zinc and alkaline earth metal salts from the fat splitting catalyst, and emulsified fatty acids and fatty acid polymers. 

The separation of individual fatty acid components from whole fatty acid distillates is achieved by fractional distillation.l8a,b However, fractional distillation cannot efficiently separate C,6-C 8 saturated from the corresponding unsaturated fatty acids. In such cases, the melting points vary considerably with the degree of unsaturation and this property is used for their separation via a number of industrial processes.I9a,b... 

Fig. 36.13. Continuous fatty acid distillation plant. (Courtesy Lurgi GmbH, Frankfurt am Main, Germany.)...

Fatty acid distillation has been done for over 100 years.17a,b However, most of the currently practiced art has originated in the past several years.18a,b The majority of the recent work falls in the following areas. 

Posada, L.R. Shi, J. Kakuda, Y. Xue, S.J. 2007. Extraction of tocotrienols frompahn fatty acid distillates using molecular distillation. Sep. Purif. Tech. 57 220-229. 

Cholesterol is a low-volatile compound, but it is more volatile than the major triglycerides of milkfat. Superheated steam can be bubbled through the oil, heating it indirectly, which provides for the latent heat of vaporization of the distilling compounds and prevents steam condensation. Thus, the temperature and pressure can be varied independently. When the sum of the partial vapor pressures of water vapor and the distillates is equal to the total pressure, water vapor and the low-volatile components, such as cholesterol and free fatty acids, distill over. 

Palm fatty acid distillate Saponifiable matter 95% Min. (basis 97%)... 

Physical Refining. The by-product in the physical refining of crude palm oil is the pahn fatty acid distillate (PFAD). It is obtained as a condensate of the volatile matters carried over from the deodorizer by the action of the stripping steam. It consists of 80-90% of free fatty acid. It has often been used as a raw material for soap making, feed compounding, and oleochemical feedstock. An important and valuable constituent of PFAD is vitamin E in the form of tocopherols and... 

Palm oil, both crude and refined, is a rich source of vitamin E, which consists of a mixture of tocotrienols and tocopherols. A technology for the preparation of a locotrinol-rich fraction (TRF) from palm fatty acid distillate has been developed. Palm Vitee (TRF in superolein and encapsulated) has been evaluated in a number of nutritional studies in both animals and humans. The nutritional properties of TRF are as follows ... 

The vapor from the deodorizer consists mainly of steam, volatile fatty substances, and some noncondensables (e.g., air). The volatile substances are condensed by creating an intimate contact between the vapor and the fatty acid distillate circulating in the scrubber. This is done either by a series of sprayers... 

Fatty Acid Distillation. Distillation of crude fatty acids removes both the low and high boiling impurities as well as odor bodies. Fatty acids are extremely sensitive to heat, oxidation, and corrosion effects. This is due to the reactive acid group at the end of the long carbon chain. These factors are taken into consideration in the design of the distillation unit and its operating parameters. Distillation is carried out under high vacuum and lower temperatures and with the shortest residence time allowable. 

Other tocotrienols (i.e., 3-, 8-) are also present (Syvaoja et al., 1986 Ong and Choo, 1997). Total vitamin E content in crude palm oil is between 600-1200 pg/g, while contents in palm oil fractions may be significantly smaller. Palm kernel oil has only <100 pg/g vitamers (Eitenmiller, 1997 Ong and Choo, 1997). Tocotrienols and tocopherols are concentrated up to eightfold in the palm fatty acid distillate compared with the crude palm oil, which enables extraction of vitamin E compounds from this by-product. 

Palm fatty acid distillate (PFAD) is a valuable by-product of palm oil processing, from which the production of tocopherols and tocotrienols is technically feasible (Ong and Choo, 1997). PFAD is wildly abundant, as palm oil is the second largest oil produced in the world. It contains 4000-8000 pg/g total vitamin E compounds, which is up to 10 times as much as crude palm oil contains (Tan, 1989 Ong and Choo, 1997). The tocopherol and tocotrienol profiles of PFAD and crude palm oil are similar, consisting of about 85% of tocotrienols, i.e., y-tocotrienol > a-tocotrienol > 8-tocotrienol (Tan, 1989). Because of cholesterol-lowering properties (Lane et al., 1999), the high level of tocotrienols makes PFAD an important source, because most other natural sources are devoid of tocotrienols. Fatty acids and esters, sterols and squalene are removed from PFAD as described above. Finally, the vitamin-E-rich product is purified and deodorized to yield a tocopherol/tocotrienol-rich product of 95-99% purity. 

Table 3.14 Composition of tocopherols and tocotrienols (% of total) in palm oils and fatty acid distillate...

The C30 hydrocarbon squalene is present at about 200-500 ppm in crude palm oil sesquiterpene (C15) and diterpene (C20) hydrocarbons are present at lower levels. Abdul Gapor and Hazrina (2000) reported squalene as high as 979 ppm in some crude oils and 791 ppm in refined oils. These levels are generally higher than that of other vegetable oils, with the exception of olive oil. Palm fatty acid distillate has 5000 ppm to 8000 ppm of squalene. Crude palm oil also has 10-80 ppm of ubiquinone 10 (Hazura et al. 1996). 

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