Bran

For other uses, seeBran (disambiguation).

Not to be confused withChaff.

Bran,also known asmiller's bran,is the component of acereal grainconsisting of the hard layers - the combinedaleuroneandpericarp- surrounding theendosperm.Corn (maize)bran also includes the pedicel (tip cap).Along with thegerm,it is an integral part ofwhole grains,and is often produced as abyproductofmillingin the production ofrefined grains.Bran is highly nutritious, but is difficult to digest due to its high fiber content; its high fat content also reduces its shelf life as the oils/fats are prone to becoming rancid. As such, it is typically removed from whole grain during therefining process- e.g. in processing wheat grain into white flour, or refining brown rice into white rice.

Wheat bran structure (E: outer layer; I: intermediate layer; A: aleurone layer)

Bran is present in cereal grain, includingrice,corn (maize),wheat,oats,barley,rye,andmillet.Bran is not the same aschaff,which is a coarser, scaly material surrounding the grain, but does not form part of the grain itself, and which is indigestible by humans.

Composition

Bran is particularly rich indietary fiberandessential fatty acids,and contains significant quantities ofstarch,protein,vitamins,anddietary minerals.It is also a source ofphytic acid,anantinutrientthat prevents nutrient absorption.

The high oil content of bran makes it subject torancidification,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 shelf life.

Nutrients (%)	Wheat	Rye	Oat	Rice	Barley
Carbohydrates(excluding starch)	45–50	50–70	16–34	18–23	70–80
Starch	13–18	12–15	18–45	18–30	8–11
Proteins	15–18	8–9	13–20	15–18	11–15
Fats	4–5	4–5	6–11	18–23	1–2

Rice bran

Rice bran is a byproduct of therice-millingprocess (the conversion ofbrown ricetowhite rice), and it contains variousantioxidants.A major rice bran fraction contains 12%–13% oil and highlyunsaponifiablecomponents (4.3%).This fraction containstocotrienols(a form ofvitamin E),gamma-oryzanol,andbeta-sitosterol;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 fiber (beta-glucan,pectin,and gum). It also containsferulic acid,which is also a component of the structure of nonlignifiedcellwalls. Some research suggests, though, inorganicarsenicis present at some level in rice bran. One study found the levels to be 20% higher than in contaminated drinking water.

Uses

Rice bran

Wheat bran

Oat bran

Bran is often used to enrichbreads(notablymuffins) andbreakfast cereals,especially for the benefit of those wishing to increase their intake ofdietary fiber.Bran may also be used forpickling(nukazuke) as in thetsukemonoofJapan.Rice bran in particular finds many uses in Japan, where it is known asnuka(Trấu;ぬか). Besides using it for pickling, Japanese people add it to thewaterwhenboilingbamboo shoots,and use it fordish washing.InKitakyushuCity, it is calledjindaand used for stewing fish, such assardines.

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 acooking oil,such asrice bran oil.

Wheat bran is useful asfeedforpoultryand otherlivestock,as part of a balanced ration with other inputs. Wheatings, a milling byproduct comprising mostly bran with some pieces ofendospermalso left over, are included in this category.

Bran was found to be the most successful slug deterrent by BBC's TV programmeGardeners' World.It is a common substrate and food source used for feeder insects, such asmealwormsandwaxworms.Wheat bran has also been used for tanning leather since at least the 16th century.

Research

As with cereal fibers andwhole grainconsumption, bran is under preliminary research for the potential to improve nutrition and affect chronic diseases.

Stability

Commonly, bran is heat-treated with the intention of slowing undesirable rancidification, but a 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 oxidizable upon prolonged storage.

See also

• Alkylresorcinols
• Cereal germ
• Phytic acid(IP6)
• Rice bran solubles
• Raisin bran