Phytosterols deodorization

Abbreviations nr—not reported TAG—triacylglycerols FFA—free fatty acids St —phytosterol fatty acyl esters St—free phytosterols FPE—phytosterol ferulate esters tocols-tocopherols and tocotrienols GL—glycolipids PL—phospholipids RBD—refined, bleached, and deodorized oil. 

Deodorization Remove volatiles and off-flavors Deodorizer distillate—a source of phytosterols and tocopherols... 

Deodorizer distillate is the material collected from the steam distillation of oils. It is a mixture of free fatty acids (especially during physical refining) tocopherols, phytosterols and their esters, hydrocarbons, and hpid oxidation products. The quality and composition of deodorizer distillate depends on the feedstock oil composition and processing conditions. Tocopherols and sterols are the most valuable components that can be recovered from the distillate, and they are used in the nutrition supplement and pharmaceutical industries (201). Typical soybean deodorizer distillate contains about 33% unsaponifiable matters, of which 11% is tocopherol and 18% sterol (202). 

The preparation of high-purity tocopherols and phytosterols involves steps such as molecular distillation, adduct formation, liquid-liquid extraction, supercritical fluid extraction, saponification, and chromatography (175). The extraction of tocopherols from soybean oil deodorizer distillate by urea inclusion and saponification of free fatty acids resulted in good recovery of tocopherols (208). To improve the separation of sterols and tocopherols, Shimada et al. (209) used a lipase to esterify sterols with free fatty acids. Then the steryl esters and tocopherols were separated better by molecular distillation. Chang et al. (210) used supercritical fluid CO2 extraction to recover tocopherols and sterols from soybean oil deodorizer distillate. A patent by Sumner et al. (211) advocated treatment of the distillate with methanol to converted free fatty acids and other fatty acid esters to methyl esters that can then be removed by a stripping operation. Then separation of sterols and tocopherols could be carried out by molecular distillation. 

A low percentage of tocopherols is lost during operations of oil neutralization, bleaching, and deodorization of sunflower oil. The tocopherols lost during deodor-ization may be recovered together other volatile compounds, from the deodorizer distillate. The distillate obtained from sunflower oil is also a good source of phytosterols. Figure 40 shows typical tocopherol levels in deodorizer distillate obtained from crude oils [based on Walsh et al. (148)]. 

Phytosterols are industrially isolated from the distillates, resulting from the deodorization of vegetable oils (1, 34—36). Phytosterols are sometimes hydrogenated to produce phytostanols (37). As the solubility of sterols and stanols is very low (< 1% at 25°C), it limits their application in food products. Esterification of sterol and stanols is, therefore, performed to make them fat-soluble and easy to incorporate in food products (37, 38). Two margarines containing 8-9% sterols (Becel Proactiv of Unilever) or stanols (Benecol of Raisio), in the form of esters, are now available in the markets in Europe and the United States. 

The unsaponifiable matter of soy, corn, canola/rapeseed, sunflower, cottonseed, peanut, and palm ranges from 10-30%, and it is composed of 40% phytosterols and 15% tocopherols (199-202). The temperature, duration, quantity of skimming vapor, and the extent of vacuum used for deodorization are the parameters that greatly influence the quality and quantity of DOD. The low content of tocopherols and sterols in the DOD often requires a concentration step however, if the starting material is soybean, this is not an issue because of the high concentration of these compounds. 

Supercritical CO2 column fractionation of soybean (57, 86, 88, 89) and rice bran oil (57) deodorizer distillates has been investigated to enrich their sterol and tocopherol contents. Brunner et al. (89) reported that the FFA were enriched in the top (in the extract), whereas the monoacylglycerols, tocopherols, and diacylglycerols were enriched in the bottom (in the raffinate) fraction during the fractionation of soybean oil deodorizer distillate. Saure and Brunner (88) achieved a tocopherol concentration of more than 70% (w/w) using continuous column fractionation of soybean deodorizer distillate where squalene was almost completely found in the top product, whereas sterols and tocopherols were enriched in the bottom product. King and Dunford (57) developed a two-step column fractionation scheme (13.6 MPa and 27.2 MPa at 313 K) for the enrichment of phytosterols from soybean and rice bran oil deodorizer distillates such that the FFA were removed in the first step and sterols were enriched in the oil fraction in the second step. 

Abbreviations nr, not reported TAG, triacylglycerols FFA, free fatty acids St E, phytosterol fatty acyl esters St, free phytosterols FPE, phytosterol ferulate esters Tocols, tocopherols and tocotrienols GL, glycolipids PL, phospholipids and RBD, refined, bleached and deodorized oil. 

The concentration of sterols, di- and triglycerides in the extract fractions was lower than the respective feed concentrations under all of the investigated operating parameters the distribution of other components was affected by fractionation time, temperature and pressure. The volatiles were enriched up to a factor of 6.3, but the decrease in volatile concentration with time resulted in concentrations lower than the feed values in the latter fractions. The free fatty acids were enriched in the latter fractions relative to their concentration in the feed. Semi-continuous processing of the deodorizer distillate at 25 MPa and 70-100°C yielded a residue containing 40% sterols and this study highlights the value of using the canola deodorizer distillate as a source for the extractiou of phytosterols. 

King JW, Dunford NT. 2001. Phytosterol-Eniiched Triglyceride Fractions from Vegetable Oil Deodorizer Distillates Utilizing Supercritical Fluid Fractionation Technology. Separation Science and Technology 37(2) 451-462. 

Vasquez et al., [22] pre-treated sunflower oil deodorizer distillates (SODD) converting free fatty acids and triacylglycerols into fatty acid ethyl esters, then put these products to CO2-SFE countercurrent and recovered higher concentrations of tocopherols and phytosterols than in SODD not pretreated. 

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 ... 

S. is part (25%) of the nonsaponificable portion of soybean oil and is obtained from the deodorizer distillates (->soybean), a by-product of soybean oil refining (- phytosterols), together with the tocopherols. There are several processes to separate the tocopher-ols from the sterols by extraction, esterification, adsorption, molecular distillation and crystallization. 

It is highly desirable, also from an ecological point of view, if wastes and materials that do not meet the specifications of nutrition are utilized industrially. These co- and by-products of food and feed production, processing and purification are often well accepted for industrial use. Examples in the area of meat production are wool, hides, bones and fats (e. g., - tallow), while plants may supply ->cotton linters, - straw from grain, - bagasse, - tocopherol and phytosterols (- steroids) from deodorizer distillate from edible oil refining. 

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