Caramel Malts, as the name implies, impart a strong caramel flavor to beer, which is the result of an extra stewing process that takes place during malting, usually in a roasting drum, between germination and kilning. See malt. In a modern malting plant, the green malt is kept at a temperature of approximately 64°C and 72°C (147°F and 162°F) during stewing. This ensures that the endosperms, in effect, are “mashed,” and the starches are turned into a sugary liquid that is trapped under the husk. Subsequently, the stewed grain needs to be dried, either in a kiln at about 90°C (roughly 195°F) for a pale malt or in the roasting drum at perhaps 200°C (roughly 390°F) for a darker malt. The stewing and drying causes the liquefied sugars to caramelize into solid, semi-crystalline, glassy, long-chain, unfermentable dextrins. Melanoidins form during this process, too. See melanoidins. Because the caramelized sugars cannot be degraded during mashing in the brewhouses, they contribute directly to wort gravity. They are also responsible for malty-sweet flavors, a deep color, a complex aroma, a fuller body and mouthfeel, and improved foam retention of the finished beer.
Historically, caramel malts were produced from green malt in a kiln covered with a tarpaulin. The tarpaulin reduced evaporation as the kiln was heated to perhaps 60°C to 75°C (140°F to 167°F) and kept at that temperature for up to 2 hours. To dry and caramelize the grain, the tarpaulin would then be removed and the temperature raised while the grain was being ventilated.
Many maltsters label their caramel malts in terms of their color values, such as Caramel 10, Caramel 40, or Caramel 120. These are numbers on the Lovibond scale (L). See lovibond. The higher the number, the darker the malt. For an approximate conversion of Lovibond into EBC (European Brewery Convention) values, simply multiply them by 1.97. At the low end of the color scale are caramel malts of as low a 2°L (approximately 4 ECB), which are often marketed as Carapils® or Carafoam®. These are typical additions, up to 5% to the grist, to the mashes of Central European blond lagers. At the other extreme are virtually black, roasted caramel malts of more than 500°L (almost 1,500 EBC). These, too, are used very sparingly, often in porters and stouts, where they rarely exceed 5% of the grist. Caramel malts between these extremes are particularly favored in such beer styles as amber ales and lagers, red ales and lagers, Märzenbiers, and bock beers, where paler versions may account for up to 40% of the grist. However, when used in high proportions, darker caramel malts can bring acrid astringency.