Wikipedia article on Malts
The oldest and most predominant ingredient in brewing is barley, which has been used in beer-making for thousands of years. Modern brewing predominantly uses malted barley for its enzymatic power, but ancient Babylonian recipes indicate that, without the ability to malt grain in a controlled fashion, baked bread was simply soaked in water. Malted barley dried at a sufficiently low temperature contains enzymes such as amylase which convert starch into sugar. Therefore, sugars can be extracted from the barley's own starches simply by soaking the grain in water at a controlled temperature; this is mashing.
Malting is a process applied to cereal grains, in which the grains are made to germinate and then quickly dried before the plant develops.
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 derived from such grains which is heavy in maltose, such as baker's malt,
- A product, based on malted milk, similar to a malted milkshake (i.e., "malts").
- whisky or beer can also be called malt as in Alfred Edward Housman's aphorism "malt does more than Milton can, to justify God's ways to Man."
Pale malt is the basis of pale ale and bitter and the precursor in production of most other British beer malts. Dried at temperatures sufficiently low to preserve all the brewing enzymes in the grain, it is light in color and, today, the cheapest barley malt available due to mass production. It can be used as a base malt, that is, as the malt constituting the majority of the grist, in many styles of beer.
Mild malt is often used as the base malt for mild ale, and is similar in color to pale malt. Mild malt is kilned at slightly higher temperatures than pale malt in order to provide a less neutral, rounder flavor generally described as "nutty".
Stout malt is sometimes seen as a base malt for stout beer; light in color, it is prepared so as to maximize diastatic power in order to better-convert the large quantities of dark malts and unmalted grain used in stouts. In practice, however, most stout recipes make use of pale malt for its much greater availability.
Amber malt is a more toasted form of pale malt, kilned at temperatures of 150-160 °C, and is used in brown porter; older formulations of brown porter use amber malt as a base malt (though this was diastatic and produced in different conditions to a modern amber malt). Amber malt has a bitter flavor which mellows on ageing, and can be quite intensely flavored; in addition to its use in porter, it also appears in a diverse range of British beer recipes.
Brown malt is a darker form of pale malt, and is used typically in brown ale as well as in porter and stout. Like amber malt, it can be prepared from pale malt at home by baking a thin layer of pale malt in an oven until the desired color is achieved.
Chocolate malt is similar to pale and amber malts but kilned at even higher temperatures. Producing complex undertones of vanilla and caramel (but not chocolate), it is used in porters and sweet stouts as well as dark mild ales. It contains no enzymes.
Black malt, also called patent malt or black patent malt, is barley malt that has been kilned to the point of carbonizing, around 200 °C. The term "patent malt" comes from its invention in England in 1817, late enough that the inventor of the process for its manufacture, Daniel Wheeler, was awarded a patent. Black malt provides the color and some of the flavor in black porter, contributing an acrid, ashy undertone to the taste. In small quantities, black malt can also be used to darken beer to a desired color, sometimes as a substitute for caramel. Due to its high kilning temperature, it contains no enzymes.
Crystal malts are prepared separately from pale malts. They are high-nitrogen malts which are wetted and roasted in a rotating drum before kilning. They produce strongly sweet toffee-like flavors and are sufficiently converted that they can be steeped without mashing to extract their flavor. Crystal malts are available in a range of colors, with darker-colored crystal malts, that is, those kilned at higher temperatures, producing stronger, more caramel-like overtones. Some of the sugars in crystal malts caramelize during kilning and become unfermentable; hence, addition of crystal malt will increase the final sweetness of a beer. They contain no enzymes.
Standard distillers malt or pot still malt is quite light and very high in nitrogen compared to beer malts. These malts are used in the production of whiskey and generally originate from northern Scotland.
Peated malt is also available; this is distillers malt that has been smoked over burning peat in order to add a dark aroma and flavor characteristic of Islay whisky and some Irish whiskey. Some recent brewers have also included peated malt in interpretations of Scotch ales, although this is generally anhistorical. It has sufficient diastatic power to self-convert. When used in large amounts, the resulting beer tends to have a very strong earthy and smoky flavour which most mainstream beer drinkers would find repulsive.
Pilsener malt, the basis of Pilsener lager, is quite pale and strongly flavored. Invented in the 1840s, Pilsener malt is the lightest-colored generally-available malt, and also carries a strong, sweet malt flavor. Usually a Pilsener beer's grain bill consists entirely of this malt, which has enough enzymatic power to be used as a base malt. The commercial desirability of light-colored beers has also led to some British brewers adopting Pilsener malt (sometimes described simply as "lager malt" in Britain) in creating golden ales. In Germany, Pilsener malt is also used in some interpretations of the Kölsch style.
Vienna malt or Helles malt is the characteristic grain of Vienna lager and Märzen; although it generally takes up only ten to fifteen percent of the grain bill in a beer, it can be used as a base malt. It has sufficient enzymatic power to self-convert, and it is somewhat darker and kilned at a higher temperature than Pilsener malt.
Munich malt is used as the base malt of the bock beer style, especially doppelbock, and appears in dunkel lager and Märzens in smaller quantities. While a darker grain than pale malt, it has sufficient diastatic power to self-convert, despite being kilned at temperatures around 115 °C. It imparts "malty," although not necessarily sweet characteristics, depending on mashing temperatures.
Rauchmalz is a German malt that is prepared by being dried over an open flame rather than via kiln. The grain has a smoky aroma and is an essential ingredient in Bamberg Rauchbier.
Acid malt, whose grains contain lactic acid, can be used as a continental analog to Burtonization. Acid malt lowers mash pH, and provides a rounder, fuller character to the beer, enhancing the flavor of Pilseners and other light lagers. Lowering the pH also helps prevent beer spoilage through oxidation.
Honey malt is an intensely-flavored, lightly-colored malt.
Melanoidin malt, a malt like the Belgian Aromatic malt, adds roundness and malt flavor to a beer with a comparably small addition in the grain bill. It also stabilizes the flavor.