Bran is the hard outer layer of grain and consists of combined aleurone and pericarp. Along with germ, it is an integral part of whole grains, and is often produced as a by-product of milling in the production of refined grains. When bran is removed from grains, they lose a portion of their nutritional value. Bran is present in and may be milled from any cereal grain, including rice, wheat, maize, oats, barley, and millet. Bran should not be confused with chaff, which is coarser scaly material surrounding the grain, but not forming part of the grain itself.
Bran is particularly rich in dietary fiber and omegas and contains significant quantitities of starch, protein, vitamins, and dietary minerals.
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 (nukazuke), as in the tsukemono of Japan.
Rice bran finds particularly many uses in Japan, where it is known as nuka (糠; ぬか). Besides using it for pickling, Japanese people also add it to the water when boiling bamboo shoots, and use it for dish washing. In Kitakyushu City, it is called Jinda and used for stewing fish, such as sardine.
Rice bran is a by-product of the rice milling process (the conversion of brown rice to white rice), and it contains various antioxidants that impart beneficial effects on human health. It is well known that a major rice bran fraction contains 12%-13% oil and highly unsaponifiable components (4.3%). This fraction contains tocotrienol, gamma-oryzanol, and beta-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 fibers (beta-glucan, pectin, and gum). In addition, it also contains 4-hydroxy-3-methoxycinnamic acid (ferulic acid), which is also a component of the structure of non-lignified cell walls. However, some research suggests that there are particularly high levels of inorganic arsenic (a toxin and carcinogen) present in rice bran, and that any health benefits may not be worth the potential detriments.[1]. Other types of bran (derived from wheat, oat or barley) contain less arsenic than rice bran. [2]
The high oil content of bran makes it subject to rancidification, one of the reasons that is often separated from the grain before storage or further processing. The bran itself can be heat-treated to increase its longevity.
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.
In Romania, the fermented wheat bran is usually used when preparing sour soups, called borscht.
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Bran is widely used as a major component in pet foods for rabbits and guinea pigs.
Rice bran is sometimes fed to horses for its nutritional value, particularly as a plant-based fat supplement. It is considered an excellent way to put weight onto a thin horse, without the problems associated with overfeeding grain. Rice bran is also included in some foods for aging dogs.
Wheat bran is fed to horses in the form of a warm porridge or mash. Bran mash is considered an excellent way to get the horse to drink more water. It is also indicated for its laxative qualities.