Bran, also known as miller's bran, is the hard outer layers of

cereal grain A cereal is any grass cultivated for the edible components of its grain (botanically, a type of fruit called a caryopsis), composed of the endosperm, germ, and bran. Cereal grain crops are grown in greater quantities and provide more food ...

. It consists of the combined

aleurone Aleurone (from Greek ''aleuron'', flour) is a protein found in protein granules of maturing seeds and tubers. The term also describes one of the two major cell types of the endosperm, the aleurone layer. The aleurone layer is the outermost layer of ...

and

pericarp Fruit anatomy is the plant anatomy of the internal structure of fruit. Fruits are the mature ovary or ovaries of one or more flowers. They are found in three main anatomical categories: aggregate fruits, multiple fruits, and simple fruits. Aggr ...

. Corn (maize) bran also includes the pedicel (tip cap). Along with

germ Germ or germs may refer to: Science * Germ (microorganism), an informal word for a pathogen * Germ cell, cell that gives rise to the gametes of an organism that reproduces sexually * Germ layer, a primary layer of cells that forms during embryo ...

, it is an integral part of

whole grain A whole grain is a grain of any cereal and pseudocereal that contains the endosperm, germ, and bran, in contrast to refined grains, which retain only the endosperm. As part of a general healthy diet, consumption of whole grains is associated ...

s, and is often produced as a byproduct of milling in the production of

refined grains Refined grains have been significantly modified from their natural composition, in contrast to whole grains. The modification process generally involves the mechanical removal of bran and germ, either through grinding or selective sifting. Overv ...

. Bran is present in cereal grain, including

rice Rice is the seed of the grass species '' Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima'' (African rice). The name wild rice is usually used for species of the genera '' Zizania'' and '' Porteresia'', both wild and domesticat ...

corn (maize) Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...

wheat Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...

oat The oat (''Avena sativa''), sometimes called the common oat, is a species of cereal grain grown for its seed, which is known by the same name (usually in the plural, unlike other cereals and pseudocereals). While oats are suitable for human con ...

barley Barley (''Hordeum vulgare''), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains, particularly in Eurasia as early as 10,000 years ago. Globally 70% of barley p ...

, rye and millet. Bran is not the same as chaff, which is a coarser scaly material surrounding the grain but not forming part of the grain itself, and which is indigestible by humans. "chaff, which is indigestible for humans"

Composition

Bran is particularly rich in dietary fiber and

essential fatty acids Essential fatty acids, or EFAs, are fatty acids that humans and other animals must ingest because the body requires them for good health but cannot synthesize them. Only two fatty acids are known to be essential for humans: alpha-linolenic ac ...

and contains significant quantities of starch,

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

vitamin A vitamin is an organic molecule (or a set of molecules closely related chemically, i.e. vitamers) that is an essential micronutrient that an organism needs in small quantities for the proper functioning of its metabolism. Essential nutrie ...

s, and dietary minerals. It is also a source of phytic acid, an

antinutrient Antinutrients are natural or synthetic compounds that interfere with the absorption of nutrients. Nutrition studies focus on antinutrients commonly found in food sources and beverages. Antinutrients may take the form of drugs, chemicals that natur ...

that prevents nutrient absorption. The high oil content of bran makes it subject to

rancidification Rancidification is the process of complete or incomplete autoxidation or hydrolysis of fats and oils when exposed to air, light, moisture, or bacterial action, producing short-chain aldehydes, ketones and free fatty acids. When these processes o ...

, one of the reasons that it is often separated from the grain before storage or further processing. Bran is often heat-treated to increase its longevity.

Rice bran

Rice bran is a byproduct of the rice milling process (the conversion of

brown rice Brown rice is a whole grain rice with the inedible outer hull removed. This kind of rice sheds its outer hull or husk but the bran and germ layer remain on, constituting the brown or tan colour of rice. White rice is the same grain without the h ...

white rice White rice is milled rice that has had its husk, bran, and germ removed. This alters the flavor, texture and appearance of the rice and helps prevent spoilage, extend its storage life, and makes it easier to digest. After milling ( hulling), t ...

), and it contains various antioxidants. A major rice bran fraction contains 12%–13% oil and highly unsaponifiable components (4.3%). This fraction contains

tocotrienol The vitamin E family comprise four tocotrienols (alpha, beta, gamma, delta) and four tocopherols (alpha, beta, gamma, delta). The critical chemical structural difference between tocotrienols and tocopherols is that tocotrienols have unsaturated i ...

s (a form of

vitamin E Vitamin E is a group of eight fat soluble compounds that include four tocopherols and four tocotrienols. Vitamin E deficiency, which is rare and usually due to an underlying problem with digesting dietary fat rather than from a diet low in vi ...

), gamma-oryzanol and

beta-sitosterol β-sitosterol (beta-sitosterol) is one of several phytosterols (plant sterols) with chemical structures similar to that of cholesterol. It is a white, waxy powder with a characteristic odor, and is one of the components of the food additive E499 ...

; all these constituents may contribute to the lowering of the plasma levels of the various parameters of the lipid profile. Rice bran also contains a high level of dietary fibres (

beta-glucan Beta-glucans, β-glucans comprise a group of β-D-glucose polysaccharides (glucans) naturally occurring in the cell walls of cereals, bacteria, and fungi, with significantly differing physicochemical properties dependent on source. Typically, � ...

, pectin and gum). It also contains

ferulic acid Ferulic acid is a hydroxycinnamic acid, an organic compound with the formula (CH3O)HOC6H3CH=CHCO2H. The name is derived from the genus ''Ferula'', referring to the giant fennel ('' Ferula communis''). Classified as a phenolic phytochemical, ferul ...

, which is also a component of the structure of nonlignified

cell Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery ...

walls. However, some research suggests there are levels of inorganic

arsenic Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, ...

present in rice bran. One study found the levels to be 20% higher than in contaminated drinking water.

Uses

Bran is often used to enrich breads (notably muffins) and breakfast cereals, especially for the benefit of those wishing to increase their intake of dietary fiber. Bran may also be used for

pickling Pickling is the process of preserving or extending the shelf life of food by either anaerobic fermentation in brine or immersion in vinegar. The pickling procedure typically affects the food's texture and flavor. The resulting food is cal ...

(''

nukazuke is a type of Japanese preserved food, made by fermenting vegetables in rice bran (nuka), developed in the 17th century. Almost any vegetable may be preserved using this technique, although some common varieties include eggplants, daikon, cabb ...

'') as in the ''

tsukemono are Japanese preserved vegetables (usually pickled in salt, brine, or a bed of rice bran). They are served with rice as an ''okazu'' (side dish), with drinks as an '' otsumami'' (snack), as an accompaniment to or garnish for meals, and as a ...

'' of Japan. Rice bran in particular finds many uses in Japan, where it is known as ''nuka'' (; ). Besides using it for pickling, Japanese people add it to the

water Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...

when boiling

bamboo shoot Bamboo shoots or bamboo sprouts are the edible shoots (new bamboo culms that come out of the ground) of many bamboo species including ''Bambusa vulgaris'' and ''Phyllostachys edulis''. They are used as vegetables in numerous Asian dishes and ...

s, and use it for

dish washing Dishwashing, washing the dishes, doing the dishes, or washing up in Great Britain, is the process of cleaning cooking utensils, dishes, cutlery and other items to prevent foodborne illness. This is either achieved by hand in a sink using di ...

. In Kitakyushu City, it is called ''jinda'' and used for stewing fish, such as

sardine "Sardine" and "pilchard" are common names for various species of small, oily forage fish in the herring family Clupeidae. The term "sardine" was first used in English during the early 15th century, a folk etymology says it comes from the It ...

. Rice bran is stuck to the surface of commercial ice blocks to prevent them from melting . Bran oil may be also extracted for use by itself for industrial purposes (such as in the paint industry), or as a cooking oil, such as

rice bran oil Rice bran oil is the oil extracted from the hard outer brown layer of rice called bran. It is known for its high smoke point of and mild flavor, making it suitable for high-temperature cooking methods such as stir frying and deep frying. It i ...

. Wheat bran is useful as feed for

poultry Poultry () are domesticated birds kept by humans for their eggs, their meat or their feathers. These birds are most typically members of the superorder Galloanserae (fowl), especially the order Galliformes (which includes chickens, quails, ...

and other

livestock Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to animal ...

, as part of a balanced ration with other inputs. Wheatings, a milling byproduct comprising mostly bran with some pieces of endosperm also left over, are included in this category. Bran was found to be the most successful slug deterrent by BBC's TV programme ''

Gardeners' World ''Gardeners' World'' is a long-running British gardening programme, first broadcast on 5 January 1968. The 2022 series is the 53rd. Its first series was presented by Ken Burras and came from Oxford Botanical Gardens. Up until 2020 most of its e ...

''. It is a common substrate and food source used for feeder insects, such as mealworms and

waxworms Waxworms are the caterpillar larvae of wax moths, which belong to the family Pyralidae (snout moths). Two closely related species are commercially bred – the lesser wax moth (''Achroia grisella'') and the greater wax moth (''Galleria m ...

. Wheat bran has also been used for tanning leather since at least the 16th century.

Brewing

George Washington George Washington (February 22, 1732, 1799) was an American military officer, statesman, and Founding Father who served as the first president of the United States from 1789 to 1797. Appointed by the Continental Congress as commander of ...

had a recipe for

small beer Small beer (also known as small ale or table beer) is a lager or ale that contains a lower amount of alcohol by volume than most others, usually between 0.5% and 2.8%. Sometimes unfiltered and porridge-like, it was a favoured drink in Medieval Eu ...

involving bran, hops, and molasses.

Research

As with cereal fibre and

consumption, bran is under preliminary research for the potential to improve nutrition and affect chronic diseases.

Stability

It is common practice to heat-treat bran with the intention of slowing undesirable rancidification. However, a very detailed 2003 study of heat-treatment of oat bran found a complex pattern whereby increasingly intense heat treatment reduced the development of hydrolytic rancidity and bitterness with time, but increased oxidative rancidity. The authors recommended that heat treatment should be sufficient to achieve selective lipase inactivation, but not so much as to render the polar lipids oxidisable upon prolonged storage. See figure 1 in particular

References

{{Authority control Cereals Food ingredients Oats