Tocotrienols important sources

The tocopherol and tocotrienol contents of selected vegetable oils are shown in Table (7). Seed oils are mostly dominated by y- or a-tocopherol, but high levels of 5-tocopherol especially characterize soybean oil, which is the richest and commercially the most used source of tocopherols (46). Rice bran and pahn oils, on the other hand, represent the important sources of tocotrienols (45, 47). Rapeseed... 

Oils and Cereals as Important Sources of Tocopherols and Tocotrienols... 

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. 

Oil extracted from rice bran and com fiber is especially rich in tocopherols, tocotrienols and sterols. Extraction of these valuable compounds is remarkably enhanced by heat pretreatment (Lane et al., 1999). For example, the level of extracted y-tocophcrol increased from 0.3% to 3.6% by subjecting com fiber to temperatures of 100-175°C (Moreau et al., 1999). Tocopherol- and tocotrienol-rich oils may be used as such as important sources of vitamin E, or the vitamers can be purified from them following the same protocols as above. 

Plant lipids increase the nutritional value of food they contain more essential FA than animal fats. They also contain tocopherols and tocotrienols, which are the most important sources of vitamin E. A disadvantage is that plant lipids (similar to animal fats) considerably increase the content of available energy. Therefore, the consumption of fried foods should be restricted because they are rich in fat. 

Palmitic Acid Oils The commodity oil richest in palmitic acid is pahn oil (44%). This oil is also rich in oleic acid (37%), contains lower levels of linoleic acid (10%), and is a valuable source of minor components, especially carotenes, toco-pherols, and tocotrienols (Section 3). Palm oil is an important world commodity in feeding the developing world. It is fractionated extensively to give a wider range of uses as palm olein and palm stearin. The only other commodity oil with a significant level of palmitic acid is cottonseed oil (27%). 

The supply of palm oil has risen considerably since around 1980. It was almost 24 million tons per annum in 2001-2002 and is predicted to exceed the production of soybean oil during the period 2011-2015 at around 37 milhon tons. The oil contains almost equal proportions of saturated (palmitic 48% and stearic 4%) and unsaturated acids (oleic 37% and hnoleic 10%). The major triacylglycerols are POP (30-40%) and POO (20-30%). The oil is used mainly for food purposes but finds some nonfood uses. It is a source of valuable byproducts such as carotene and tocopherols and tocotrienols (vitamin E). Red palm oil is a carefully prepared oil that retains about 80% (500-700 ppm) of the carotenes present in the crude oil and is a valuable dietary source of these important compounds (42). 

Good sources of vitamin E are vegetable oils, such as com, soy, and peanut oii. Animal fats, such as butter and lard, contain lowrer amounts of the vitamin. The content of the most important form of vitamin E, a-tocopherol, in various foods is as follows. Com oil contains about 16 mg of a-tocopherol per 100 g sunflower oil 50 mg/100 g, wheat germ oil 120 mg/100 g and fish, eggs, and beef 0.5 to 2,0 rng/100 g. In plants, a-tocopherol resides in chloroplasts, while other forms of tocopherol ( i-, y-, and 5-tocopherol) occur elsewhere in the plant cell. Tocotrienols, which also have vitamin E activity, are not found in the green parts of plants, but in the bran and germ of seeds... 

Other than drugs, food is the sole source of exogenous antioxidants. These antioxidants are supplied by plants and food additives. The most active dietary antioxidants contained in plants are phenolic and polyphenolic compounds. The most important among them are tocopherols and tocotrienols (tocols), as well as flavonoids. Tocopherols retard the formation of hydroperoxides, inhibit rearrangement of cis, trans peroxyl radicals to trans, trans isomers (Porter et al., 1995), inhibit peroxide decomposition (Hopia et al., 1996 Makinen and Hopia, 2000), and inhibit the 3-scission of alkoxyl radicals (Frankel, 1998). The ability of tocopherols to inhibit the formation of hydroperoxides decreases in the order a-tocopherol > y-tocopherol > 5-tocopherol at a low initial level of addition (100 ppm), a reverse order of activity being revealed when the initial... 

Vegetable oils, especially the seed oils, are rich sources of tocopherols. Refining waste from the edible oil industry has emerged as an important raw material for the extraction of vitamin E, and the residues of the soybean refining industry are one such source. Tocotrienols, on the other hand, are found predominantly in palm oil and in cereals such as barley and rice bran oils. With the emergence of palm oil as the second largest edible oil in world markets, technological advances have been made to similarly extract tocotrienol-rich palm vitamin E from the refinery wastes of the industry. The resultant product, often termed palm tocotrienol-rich fraction (TRF), is currently available on a commercial scale from Malaysia. A similar tocotrienol-rich vitamin E preparation derived from rice bran oil is also available in the U.S. 

Vitamin E has eight biologically active forms [1] four tocopherols (saturated isoprenoid side chain) and four tocotrienols (imsaturated iso-prenoid side chain), designed as a-, P-, y-, and 5-according to the number and position of methyl groups on the chromanol ring. Of these, a-tocopherol is the most important (plant sources) and active. 

---