Wheat germ is the embryo of a wheat berry (kernel) and forms about 2.5 percent of the total berry. Wheat bran (the seed coat) forms 14.5 percent and the starchy endosperm forms 83 percent. Commercial wheat germ is a by-product of milling the endosperm to make white flour. Wheat germ oil is expeller pressed from the wheat germ or solvent extracted using acetone, hexane or methanol. The oil is then filtered, degummed, bleached and deodorized. It is sold as a health food or as an animal feed supplement.
Oil Content
Wheat germ oil is high in two essential polyunsaturated fatty acids that cannot be synthesized in the body and must be consumed in the diet, linolenic acid and linoleic acid. Linolenic acid reduces cholesterol and lowers the risk of heart disease. Linoleic acid is a precursor to prostaglandin hormones, which counteract inflammation.
Warning
The polyunsaturated fatty acids in wheat germ oil are unstable, meaning they will oxidize (bond with oxygen) and become rancid in as few as three days if not kept refrigerated in airtight containers and shielded from light. Fatty acids are chains of carbons with bond sites for hydrogen atoms on both sides. A polyunsaturated fat has more than one vacant site where a hydrogen could be bonded but is not. Saturated oils, such as butter, and mono-unsaturated oils, such as olive oil, are stable at room temperature, which means that, unlike wheat germ oil, they are slow to oxidize and slow to become rancid.
Nutrition
Wheat germ oil has the highest vitamin E content of any vegetable oil, as high as 2500 mg (0.09 ounces) per kilogram (35.27 ounces) of oil. The recommended daily dietary intake of vitamin E for adults is 15 mg. Vitamin E is an antioxidant, meaning that it can donate an electron to neutralize free radicals (oxides or peroxides with highly reactive unpaired electrons), which can damage living cells. Vitamin E in the wheat berry germ also prevents rancidity while the seed is dormant. A Missouri Botanical Garden Bulletin in January 1921 noted that testing 16-year-old wheat seeds had yielded an 8 percent germination rate, although by year 30 the germination rate was zero.
Flour
The U.S. Food and Drug Administration requires that products marketed as "whole wheat" have the same proportion of germ, bran and endosperm as the living seed does. Oil in the germ gives whole wheat products a pleasant "nutty" flavor, plus a higher vitamin and mineral content than white flour products have. Whole wheat flour has a shelf life of six months to one year when kept tightly sealed and refrigerated. By comparison, bleached and fortified white flour has a shelf life of eight months when kept in a kitchen cabinet at room temperature or one year in a refrigerator.
Organic
Organic unrefined wheat germ oil is dark brown in color and smells and tastes of the wheat kernel. If not recently cold pressed with an expeller process and immediately refrigerated, the unrefined oil may be rancid by the time it reaches the market. When carefully stored in an airtight container, shielded from light and refrigerated, wheat germ oil has a shelf life of up to two months.
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