Cereal grains are the fruit of plants belonging to the grass family (Gramineae). Ten thousand years ago, wheat underwent spontaneous mutations causing this grass to hang onto its seed rather than scatter it to the wind. Although this change was not in the interests of the wheat from the standpoint of its own reproduction, it enabled humans to store seed for the winter. The calorie density of grains prevented starvation and so played an important role in human history worldwide. In China, rice was domesticated about 6,500 years ago, and in the New World corn was domesticated about 3,500 years ago.
Until the past century, most grains were consumed as "whole" grains. In other words, the grain kernels were intact — not stripped of their vitamins, minerals, and fiber. Whole grains provide fiber, protein, complex carbohydrates, lignans, phytates, other phytochemicals, vitamins, and minerals. Fat-soluble vitamins are found in the germ of the grain, and B vitamins and phytochemicals are found in the husk or bran. Grain and grain products are also naturally low in fat.
Whole grains can be consumed plain as hot cereals, used in pilafs, added to baked goods, and eaten in dozens of other ways. Hundreds of products are made from grain. Two of the main ones —bread and pasta — are diet staples in nearly every culture on every continent, from couscous in North Africa to soba (buckwheat noodles) in Japan. Grains and grain products literally feed the world, providing most of the calories and much of the protein consumed by the world’s population.
Basics
Grains are the seeds of plants. Although the grains eaten by humans belong to a wide range of botanical families, they have the same basic structure and contain these components, from which plants begin to grow:
Bran — This is the outer layer of the grain seed. It’s full of B vitamins, trace minerals, and, especially, fiber.
Endosperm — Sometimes referred to as the kernel, the endosperm contains the majority of the material within the seed and is meant to nourish a seedling. The endosperm is where most of the protein, carbohydrates, and small amounts of vitamins are located. It is composed mainly of starch, and often it is the only part of the grain that is eaten.
Germ — The germ is the part of the seed from which the new plant sprouts. As the embryo within the seed, it has the highest concentration of nutrients, including B vitamins, trace minerals, and some proteins. It also contains fat, which increases its perishability.
Grains are usually milled before they are used as food. Milling usually means that the bran and any husk surrounding the grain seed (along with the nutrients they contain) are removed. Then the seeds are ground in a process that converts the grain into flour or other products. The product’s use and name often depend on how much of the bran is left. Wheat, for example, can be milled into whole-grain flours that contain all parts of the seed. Refined flours, which are used most often by Western nations, contain only the endosperm: the bran and germ are removed (along with much of the grain’s nutrition).
Nearly any grain can be milled and made into products such as bread, cereal, or pasta—food staples worldwide—with varying degrees of success depending on the chemistry of the grain. History has taught us which grains work best and in what combinations.
Gluten, which is found in grain protein, gives bread its springy texture. It becomes stretchy and thickens when liquid is added to the flour and the combination is kneaded. The resulting gas from the fermentation of the carbohydrate in the flour is trapped by the dough, causing the gluten to stretch and, thus, the bread to rise. Because wheat and rye contain the highest quantities of gluten, flour made from these grains has proved best suited for making bread. Other grains, such as corn, have less gluten, and products made from them are more crumbly.
In most countries, the highest proportion of cultivated land is devoted to grains. Crops such as wheat, rice, corn, barley, oats, and millet remain critical components in the diets of people worldwide. Wheat is the most widely grown grain. But, because multiple crops of rice can be grown in a year in tropical areas, a nearly equal amount of rice and wheat are grown each year.
Nutrition
The mix of nutrients supplied by grains varies. But because grain seeds are composed mostly of starch, between 65 and 90 percent of the calories supplied by grains are carbohydrates. Between 8 percent and 15 percent of calories come from protein, and fat contributes the remainder of the calories. Because grains are plant-based proteins, they do not supply all of the amino acids (the building blocks of protein) that your body needs. However, grains also do not have the twin disadvantages of animal-based protein—saturated fat and cholesterol, both of which are linked to cardiovascular disease. Grains can be eaten in combination with other foods—such as legumes, small servings of meat or poultry, and dairy foods—to provide the complete balance of amino acids.
Important minerals found in whole grains are iron, phosphorus, magnesium, and zinc. Whole grains are also a source of B vitamins (niacin, thiamin, riboflavin) and antioxidants, such as vitamin E and selenium. Scientists are just beginning to explore the health role of substances called "phytochemicals," which are also found in whole grains.
Grains are rich in dietary fiber, both insoluble fiber (which helps bowel function and may reduce the risk of some kinds of cancer) and soluble fiber (which may have a role in lowering blood cholesterol levels).
The refining and processing of grains remove many of the nutrients grains naturally provide. The bran and the nutrients it contains are often removed during the milling process. Refined wheat flour has both the bran and the germ removed. Many grain products are enriched, meaning nutrients originally found in the grain are added back to the product during processing. But not all the nutrients are returned. Insoluble fiber is milled away when the bran is removed, and antioxidants usually are not added back into refined flours. Phytochemicals also may be missing in refined products.
The bottom line is that even though refined grains are a good source of many nutrients, whole grains are better. You can tell whether a product is made from whole grain by checking the ingredient listing of the label. Look for the words "whole grain," indicating that the product contains the endosperm, bran, and germ, and all the benefits they bring.
Selection
Grains, even those that have been processed or lightly cooked, contain some of their natural oils. Over time, they may go rancid, which is why ensuring freshness when buying them is key. Look for grains that are in sealed packages. This protects them from air, moisture, and spoilage. Some may have freshness or "best if used by" dates to help ensure quality. If you are buying in bulk, check whether the store has a rapid turnover of that particular product. There may not be a great demand for bulgur in supermarkets, for example, and so the product may have been on the shelf for some time. In contrast, specialty food markets or those specializing in natural foods may have greater demand for the product, sell more of it, and therefore have a fresher product. Grains also should smell fresh and appear clean and free of debris.
Storage
Because grains may attract insects or may become moldy if they become moist, keep them in tightly closed, moisture-proof containers. Grains can be stored at room temperature, but they will remain fresh longer if stored in the refrigerator, where they will keep for several months. Most grains can be kept much longer if stored in the freezer. They do not need to be thawed before cooking. Cooked grain may be stored in the refrigerator for several days and then reheated.
Preparation
Whole grains are hard and dry. Thus, cooking involves not only heating them but also rehydrating them. For that reason, whole grains, with few exceptions, are cooked in liquid. Here’s a traditional method for doing so:
• Bring water (or other liquid, such as a stock) to a boil. Many cooks use a ratio of two to three parts water to one part grain.
• Add grains and other seasonings.
• Cover mixture and reduce to a simmer.
• Simmer until most of the liquid is absorbed.
• Remove mixture from heat and drain excess liquid if necessary. Let sit for approximately 5 minutes, then fluff with a fork.
Beyond the Basics
Innovative uses of grains include the production of modified starches, caloric sweeteners, and fat substitutes. Beta-glucan, a fat-like gel made from enzyme-treated oat bran, is sold as a cholesterol-lowering fat replacement, although more testing is needed to determine its effectiveness. Several food enzymes are produced by fermentation based on grain. Wheat gluten may be used to produce flavor enhancers such as glutamate or diet supplements such as glutamine. There is also a vast range of industrial applications. None of these, however, are likely to overtake in importance the role of grains in feeding the world.
Cooking times vary depending on the kind of grain used, how it has been processed, and whether it has been precooked (bulgur and kasha are often lightly cooked, then dried before they are sold in stores). Most cooks recommend cooking whole grains as you would pasta. Simply cook them until tender—a time that may range from 8 minutes for "instant" types of white rice to more than an hour for whole wheat or other unmilled grains.
Some grains that are particularly tough—such as wheat or rye—may be easier to cook if they are first soaked. Rinsing whole grains before cooking also is advised to remove debris or other residues.
The text that follows provides more detailed information about specific grains and the foods made from them. The topic is organized into two sections:
• Grains
• Grain Products
