grain

Grain is the small, dry seed of cereal crops harvested for food, feed, or industrial use. Most grains come from grasses in the family Poaceae, including true cereals such as wheat, rice, maize (corn), barley, oats, rye, and sorghum. Pseudocereals such as quinoa and buckwheat are closely related in culinary use but botanically distinct. A grain kernel has three main parts: the bran, a protective outer layer; the germ, the embryonic plant; and the endosperm, which stores starch. Milling and processing can remove the bran and germ to produce refined grains or preserve all parts as whole grains.

Grains are staple foods across cultures, providing carbohydrates and varying amounts of protein, fiber, and micronutrients. Some grains contain gluten, a group of storage proteins found in wheat, barley, and rye, which is a consideration for people with celiac disease or gluten sensitivity. Grain processing affects texture, flavor, and nutritional profile; whole grains retain more nutrients but require proper storage to avoid spoilage. Storage requires cool, dry conditions; pests such as weevils can be a concern, and aflatoxins can form in damp conditions.

Global production concentrates on a few crops and major producing regions. Large producers include countries in Europe, Asia, and the Americas, along with others depending on the crop. In addition to direct food use, grains are processed into flour, meal, starch, and animal feed, and are used in industrial products such as ethanol.

Grain can also refer to a unit of mass used in some measurement systems, defined as 1/7000 of a pound or about 0.0648 grams.