Malt

Infobox on Malt
Example of Malt
Facts
Origin	-
Stowage factor (in m3/t)	-
Humidity / moisture	<14%
Ventilation	See Grain
Risk factors	See text

Malt

Description / Application

Malt is germinated cereal grains that have been dried in a process known as "malting". The grains are made to germinate by soaking in water, and are then halted from germinating further by drying with hot air. Malting grains develop the enzymes required to modify the grain's starches into sugars, including the monosaccharide glucose, the disaccharide maltose, the trisaccharide maltotriose, and higher sugars called maltodextrines. It also develops other enzymes, such as proteases, which break down the proteins in the grain into forms that can be used by yeast. Malt also contains small amounts of other sugars, such as sucrose and fructose, which are not products of starch modification but were already in the grain.

Malted grain is used to make beer, whisky, malted shakes, malt vinegar, confections such as Maltesers and Whoppers, flavoured drinks such as Horlicks, Ovaltine and Milo, and some baked goods, such as malt loaf, bagels and rich tea biscuits. Malted grain that has been ground into a coarse meal is known as "sweet meal". Various cereals are malted, though barley is the most common. A high-protein form of malted barley is often a label-listed ingredient in blended flours typically used in the manufacture of yeast breads and other baked goods.

The term "malt" refers to several products of the process: the grains to which this process has been applied, for example malted barley; the sugar, heavy in maltose, derived from such grains, such as the baker's malt used in various cereals; or a product based on malted milk, similar to a malted milkshake (i.e., "malts").
Malting is the process of converting barley into malt, for use in brewing, distilling, or in foods and takes place in a maltings, sometimes called a malthouse, or a malting floor. The malting process starts with drying the grains to a moisture content below 14%, and then storing for around six weeks to overcome seed dormancy. When ready, the grain is immersed or steeped in water two or three times over two or three days to allow the grain to absorb moisture and to start to sprout. When the grain has a moisture content of around 46%, it is transferred to the malting or germination floor, where it is constantly turned over for around five days while it is air-dried. The grain at this point is called "green malt". The green malt is then kiln-dried to the desired colour and specification. Malts range in colour from very pale through crystal and amber to chocolate or black malts.

The sprouted barley is kiln-dried by spreading it on a perforated wooden floor. Smoke, coming from an oasting fireplace (via smoke channels) is then used to heat the wooden floor and the sprouted grains. The temperature is usually around 55 °C. A typical floor maltings is a long, single-storey building with a floor that slopes slightly from one end of the building to the other. Floor maltings began to be phased out in the 1940s in favour of "pneumatic plants". Here, large industrial fans are used to blow air through the germinating grain beds and to pass hot air through the malt being kilned. Like floor maltings, these pneumatic plants are batch processes, but of considerably greater size, typically 100 ton batches compared with 20 ton batches for floor malting.

Barley is the most commonly malted grain, in part because of its high diastatic power or enzyme content, though wheat, rye, oats and rice are also used. Also very important is the retention of the grain's husk, even after threshing, unlike the bare seeds of threshed wheat or rye. This protects the growing acrospire (developing plant embryo) from damage during malting, which can easily lead to mould growth. It also allows the mash of converted grain to create a filter bed during lautering. Malt is often divided into two categories by brewers: base malts and specialty malts. Base malts have enough diastatic power to convert their own starch and usually that of some amount of starch from unmalted grain, called adjuncts. Specialty malts have little diastatic power; they are used to provide flavour, colour, or "body" (viscosity) to the finished beer. Specialty caramel or crystal malts have been subjected to heat treatment to convert their starches to sugars nonenzymatically. Within these categories is a variety of types distinguished largely by the kilning temperature (see mash ingredients). In addition, malts are distinguished by the two major species of barley used for malting, two-row and six-row.