Malting is a method of transforming cereal into malt. Malting is a regulated germination mechanism that stimulates the enzymes of the resting grain resulting in the transfer of cereal proteins and other macromolecules. Generally, barley is the grain used for the production of malt. Malt is mainly used for brewing or making whisky, but can also be used to make malt vinegar or malt extract. Various grains are used for malting, most common being barley, sorghum, wheat and rye.
The highest amount of malt is used in the brewing of beer and the taste of beer is mainly the result of the malt from which it was made. The next most important use of malt is distilled alcohol for whiskey and other drinks. Malt extracts are also used for flavoring, enzyme activity and starch content in food products such as flour, malt vinegar, breakfast cereals, baby food, confectionery and baked goods.
Steps Involved in Malting Processes
The steps involved in malting process which help to convert barley or other cereal grains into malt for use in brewing, distilling, or other foods are as shown below:
Drying
The malting process begins by drying grains to a moisture content of less than 14 per cent and then preserving them for about six weeks to avoid seed dormancy. Barley received in a malt house with a moisture content of more than 14 per cent must be dried before it can be processed safely without loss of germinative capacity. Moisture is eliminated by circulating heated air (up to 50 °C) through the grain and can be generated using dedicated grain dryers.
Steeping
When ready, the grain is dipped or steeped in water two or three times for two or three days to allow the grain to absorb moisture and to begin to germinate. In the steeping process, the grain is put in a water tank and absorbs moisture, allowing the embryo to wake up within the seed. The dampened grain is then allowed to germinate or sprout, and tiny rootlets rise out of the bottom of the kernel.
Germination
When the grain has a moisture content of about 46%, it is moved to the malting or germination floor, where it is continually turned over for around four to six days while it is air-dried. During germination, enzymes are activated that the embryo plant uses to break down the starch in its kernel and to develop it into root and stem structures. These starch-splitting enzymes also permeate the rough, brittle outer wall of the seed, transforming it into a smoother and more soluble shape and giving it a distinctive malty taste. The germination process needs cooled and moistened air to pass through the mass of the sprouting grain, which must be carefully moved to keep the rootlets from transitioning. In current malting techniques, germination is typically conducted in spinning drums or in tanks fitted with agitators. This method was largely replaced by floor malting, in which the moistened grain was scattered over concrete floors and made into a pellet. When the desired biological alteration in the grain has been accomplished, the mechanism of germination is halted by Kilning.
Pre-toasting or Kilning
The grain at this point, called “green malt” is then dried and toasted in the oven (or oven) to the desired color and specification. Malts range in color from very pale to crystal and amber to chocolate or black malt. At this stage, the germinated grain, called green malt, is dried by streams of heated air entering the furnace floor through perforations. Timing and heat intensity applied to the boiling process affect the taste and color development of the malt.
Enzymes formed in the barleycorn during germination break down the starch contained in the seed kernel into simpler carbohydrates, primarily malt sugar (maltose). Other enzymes are often contained in a grain that can break down proteins into simpler nitrogen compounds. In the brewing process, malt is added to the cereal mash in order to transform the enzyme of the former into maltose. Maltose is then fermented by yeast, resulting in alcohol and carbon dioxide, which give beer its distinctive properties.
Malt extract is produced by grinding malt, separating the solids, and then using an evaporator to concentrate the aqueous fraction. The resulting substance is a thick syrup containing sugar, vitamins and minerals. Specialized malts to improve the color and taste of beers are produced by controlled heating of wet or dry malt (e.g. crystal malt and “chocolate” or black malt).
Smoking
The sprouted grain is then further dried and smoked by spreading it to a perforated wooden board. Smoke coming from an oasting fireplace (through smoke channels) is then used to heat the wooden floor and the sprouted grains. Usually, the temperature is about 55 °C (131 °F). Smoked Malt is the main malt for smoked ales or lagers. However, the most common use of smoked malt is not for beer, but for whisky, especially Scotch. Many traditional Scottish distilleries—some of whom still have their own malting—rely on peat-smoked malt for their mashes. Whisky malt is typically dried and cured in peat-fueled, direct-fired ovens. Since peated malt appears to be very acridic, it is rarely used in brewing. When included, it’s never a base malt, but it’s just added to the grist in very limited amounts, enough to give a nuanced taste.
