Phytosterols 33 refining

In the initial black Hquor concentration, saponified fatty and resin acid salts separate as tall oil soaps (see Tall oil). These soaps can be skimmed from the aqueous spent Hquor, acidified, and refined to give a cmde tall oil composed of resin acids, chiefly abietic and neoabietic fatty acids, chiefly oleic and Hnoleic and an unsaponifiable fraction made of phytosterols, alcohols, and hydrocarbons. Tall oil is fractionated primarily into fatty acids (see... 

Soybeans and products thereof, except fully refined soybean oil and natural tocopherols, soybean oils derived phytosterols and phytosterol esters, and stand ester... 

Unsaponifiable matter. Oils and fats contain variable amounts of sterols, hydrocarbons, tocopherols, carotenoids, and other compounds, collectively referred to as unsaponifiable matter because they do not produce soaps upon hydrolysis (Table 6). The sterol and tocopherol composition of commodity oils is discussed in another chapter. Some of these minor components are removed during refining, and the resulting concentrates may be useful byproducts, for example, tocopherol antioxidants. Characteristic fingerprints of minor components, particularly phytosterols and tocopherols, are also used to authenticate oils and detect adulteration (18). 

STEROLS Phytosterols are mostly associated with unrefined vegetable oils and exist as derivatives of phenolic acids (e.g., ferulic acid). Several studies are available on antioxidant activity of sterols and their derivatives from sources such as corn fiber, oats, and rice. These compounds can be obtained from the unsa-ponifiable fraction that is removed during vegetable oil refining. Triterpene alcohols and hydrocarbons (131), or sterols (Figure 20) from oats (132, 133), rice (134, 135),... 

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. 

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). 

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. 

Oil recovered by solvent extraction or mechanical pressing is termed crude soybean oil and contains various classes of lipids. It consists primarily of neutral lipids, which include tri-, di- and monoacylglycerols, free fatty acids, and polar lipids such as phospholipids. It also contains a minor amount of unsaponifiable matter that includes phytosterols, tocopherols, and hydrocarbons such as squalene. Trace metals are found in soybean oil in ppm concentration. When the oil is refined, concentrations of all minor constituents are reduced. The typical composition of crude and refined soybean oil is shown in Table 2.2. 

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. 

Table 10.4 Phytosterols in refined corn germ oil, corn fiber oil and corn aleurone (values represent free + esterified phytosterols, measured after saponification)... 

Both phytosterols and tocopherols are co-extracted with oil and partially removed during soybean oil refining. The refining by-product is one of the important sources for commercial phytosterol and tocopherol production. 

One approach to increase the plQlosterol ester content of vegetable oils is via refining rather than isolating em from the by-products and then adding them back to the oil (26). Such a processing scheme simplifies the eruichment process and improves the economic feasibility of the production. Dunford and fCing (27) were able to increase the total phytosterol ester content of rice bran... 

Gertz and Kochhar (2001) have shown that phytosterols from rapeseed and sunflower enhance the stability of refined oils at higher temperatures. The authors suggested that a radical peroxidation mechanism predominates at lower temperature, and acid-catalyzed chemical reactions occur predominantly at frying temperatures during actual frying operations. The probability of two different mechanisms may provide an answer to the different autoxidative activity of sterols. Sterols are almost inactive at temperatures lower than 120°C. 

Cold-pressed plant oils and refined plant oils from Polish markets were assessed for contents of sterol oxidation products. The content of oxyphytosterols in refined oils was 2 to 2.5 times higher than in cold-pressed oils. The 7-hydroxy-phytosterols and 7-keto-phytosterols epimers were the predominant compounds in cold-pressed oil, whereas epoxy derivatives were predominant compounds in refined oils. Percentage composition of oxyphytosterol fraction differed from the phytosterol percentage fraction (Figure 6.5) (Rudzinska et al., 2001). 

During the refining, the sensory value of the oil is substantially improved but the nutritional value is impaired by partial removal of carotenoids, tocopherols, and phytosterols, and by moderate isomerization of polyunsaturated acyls into their cis,trans isomers linolenic acid is especially sensitive (Cmolik et al., 2000). The amount of trans isomers should not exceed 1%. Refined oils are nearly flavorless, tasteless, and colorless, and possess good stability against autoxidation. 

After suitable modification it can be used as a solvent, a lubricant, and as biodiesel. Valuable by-products recovered during refining include lecithin, tocopherols, and phytosterols. Attempts to modify the fatty acid composition by seed breeding or genetic modification are directed to reducing the level of saturated acid or linolenic acid, or increasing the content of stearic acid. ... 

Phytohormone-derived anticancer drugs, 3864 Phytohormones, 230 Phytol, 2733, 2734, 2737, 2744, 3176 Phytolacca dioica, 4094 Phytonutrients, 1740 Phytosterol oxides (PSOs), 3451-3452 Phytosterols, 2416, 2422, 2568 bioavailability, 3441 compared to phytostanols, 3442 Phytotoxic, 3488 Phytotoxicity, 1941 pH-zone-refining, 2150 PI. See Pinene (PI)... 

The composition of phytosterols and tocopherols does not change appreciably during refining. Therefore, an analysis of these coirpounds is suitable for the identification of the t)q)e of fat. On the other hand, cholesterol can increase during steaming, e. g., due to the cleavage of... 

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