The Es Have It

Vitamin E and the related tocopherols are natures antioxidants, existing in significant levels in vegetable oils contained in grains, seeds and nuts. There, they protect the high levels of unsaturated fatty acids in these vegetative materials from oxidation. In our diets, vitamin E serves as a fat-soluble antioxidant vitamin, preventing cell membrane damage by inhibiting phospholipid peroxidation and disrupting free-radical chain reactions from lipid peroxides. And not only do tocopherols fight oxygens deleterious effects in our bodies, they can provide the same service to the products we formulate.

E by the letter

Natural tocopherols consist of a mixture of four different oil-soluble molecules with similar structures and are commercially derived from vegetable oils. These differ from each other by the number and position of the methyl groups on the aromatic ring. The forms include d-alpha- (commonly known as vitamin E), d-beta-, dgamma- and d-delta-tocopherols. Synthetic tocopherols, designated by the prefix dl, consist of eight sterioisomers, only one of which is molecularly identical to alpha-tocopherol. Another series of compounds, the tocotrienols, are also members of the vitamin E family. Their structure differs from the tocopherols due to three double bonds in the molecules carbon side chains.

The Code of Federal Regulations (Title 21, Vol. 3, Sec. 184.1890) states that both commonly used forms of vitamin Enatural as the d-alpha form and synthetic in the dl-alpha formare considered GRAS. The morestable ester forms, such as tocopheryl acetate, are also commonly used, says Herb Woolf, Ph.D., senior nutritionist, human nutrition group, BASF Corporation, Florham Park, NJ.

Dietary-sourced alpha-tocopherol is the natural form, which is labeled as d-alpha-tocopherol or RRRalpha-tocopherol, says David Cai, Ph.D., research manager/ principle scientist, Cognis Nutrition & Health, La- Grange, IL. Synthetic forms of alpha-tocopherol, which can be manufactured from petroleum, are often labeled as dl-alpha-tocopherol or all rac-alpha-tocopherol.

The tocopherol content in nature varies by the source, says Brent Flickinger, Ph.D., senior research manager, Nutritional Science ADM Research, ADM, Decatur, IL. For example, soybean oilthe source of much commercial natural vitamin Econtains all four different molecules in the following approximate proportions: d-alpha-tocopherol, 13.0%; d-beta-tocopherol, 1.5%; d-gamma-tocopherol, 64.0%; and d-delta-tocopherol, 21.5%. However, he notes that in RBD sunflower and canola, the alpha form predominates.

Research suggests that the delta and gamma forms are slightly stronger antioxidants in food systems than the alpha and beta forms. However, in the human body, the alpha-tocopherols have the highest bioavailability.

Although natural tocopherol has many benefits, synthetic forms can supply certain advantages. So-called synthetic vitamin E is GMO-free, as well as devoid of any environmental contaminants and pesticides, explains Wolff. A closed continuous process to produce vitamin E by organic synthetic routes is a consistent, cost-effective means of producing a vital nutrient on a least-cost basis.

Getting a reaction

Tocopherols act as antioxidants by donating the hydrogen of the hydroxyl group to the fatty radical formed during autoxidation. When the fatty radical reacts with tocopherols stable antioxidant radical, the chain reaction terminates. When using vitamin E as an antioxidant, product designers need to remember it doesnt prevent autoxidation; it delays its onset by eliminating the free fatty radicals. Therefore, it is necessary to add the antioxidant before the onset of the oxidative process.

Combining tocopherols and other antioxidants with certain compounds often results in a synergistic effect. Synergists such as ascorbic acid, ascorbyl palmitate, citric acid and lecithin, used together with tocopherols, provide an antioxidant increase that is greater than the sum of the effect of either material used alone. The ascorbyl palmitate, and possibly the ascorbic acid, are thought to regenerate the tocopherols.

Mixed tocopherols can provide equivalent or better oxidation protection than the synthetics on a per-weight basis, especially in products with animal fats, such as processed meats and those with milkfat.

Some researchers have found gamma-tocopherol, and others have shown delta-tocopherol, to have the most antioxidant activity in foods, says Cai, noting that a mixture of natural tocopherol isomers has the most antioxidant activity, because it contains naturally occurring d-alpha, d-beta, d-gamma and d-delta tocopherols. He says the companys mixed tocopherols ingredient has low volatility and increased solubility compared to synthetics. It is used mainly to guard against oxidation and extend a products life naturally.

In general, the addition method and type of tocopherol used varies with the application and process conditions. Even distribution insures optimal protection. Liquid tocopherols are completely miscible in all fats and oils, ensuring thorough distribution throughout the fat. The level needed varies with the application. In general, the optimal finished- product level ranges from 0.01% to 0.20% of the total fat content.

Tocopherols are typically dispersed in vegetable oil, producing a bland flavor with a brownish-red appearance. With their typical very low use levels, they do not affect finished-product flavor or appearance. Spray-drying them in a carrier, such as gum acacia, forms a water-dispersible powder.