Wheat, a cereal grain cultivated for thousands of years, is a fundamental food source globally. Its adaptability allows it to thrive in diverse climates, making it a widespread crop that provides substantial daily calories and nutrients for billions.
Nutritional Components
Wheat grain is a source of various nutrients, including carbohydrates, proteins, and fats. On average, a wheat kernel contains about 70% carbohydrates, 12% protein, and 2% fat. These macronutrients provide energy for bodily functions, with carbohydrates being the primary energy source.
Beyond macronutrients, wheat offers a range of vitamins and minerals. It provides B vitamins like thiamine, riboflavin, niacin, and folate. Minerals include iron, magnesium, zinc, and selenium. The concentration of these nutrients varies depending on which part of the wheat kernel is consumed.
Unique Compounds
Wheat contains specific compounds that contribute to its characteristics, notably gluten. Gluten is not a single protein but a complex network formed when two main proteins, gliadin and glutenin, from wheat flour combine with water. This protein network provides dough with its elasticity and strength, allowing it to stretch and trap gas bubbles during fermentation, which gives baked goods their characteristic texture and rise.
Other noteworthy compounds in wheat are phytochemicals, plant-derived substances recognized for their antioxidant properties. These include phenolic acids, such as ferulic acid, found primarily in the outer layers of the grain. Other phytochemicals like flavonoids, lignans, and carotenoids are also present. Phytic acid, another compound found in wheat, can bind to minerals like iron and zinc, potentially affecting their absorption in the body.
How Processing Changes Content
The wheat kernel consists of three distinct parts: the bran, the germ, and the endosperm. The bran is the fiber-rich outer layer containing B vitamins, minerals like iron, zinc, magnesium, and phytochemicals. The germ, the embryo of the seed, is rich in healthy fats, vitamin E, B vitamins, and antioxidants. The endosperm, the largest part, primarily contains starchy carbohydrates and some protein.
Refining wheat involves removing the bran and germ, leaving mostly the endosperm. This process significantly reduces the nutritional content of the flour. For instance, refining can strip away more than half of wheat’s B vitamins, nearly all of its fiber, and a substantial amount of vitamin E. Minerals can be reduced by up to 72% in refined products compared to whole wheat.
While some nutrients, like certain B vitamins and iron, may be added back to refined flours through enrichment, fiber and many phytochemicals are not replaced. Consequently, whole wheat products retain a more comprehensive nutritional profile, including higher fiber content, numerous vitamins, minerals, and beneficial phytochemicals, compared to their refined counterparts.