Understanding Malting and Mashing Barley for Homebrewing
Of the four main ingredients used in homebrewing beer (barley, hops, yeast, and water), barley makes the biggest contribution. Barley gives beer its color, underlying flavor, sweetness, body, head of foam, and mouthfeel. Barley also contributes the natural sugars that feed the yeast, which in turn converts the sugars into alcohol and carbon dioxide during fermentation.
Before you can brew with barley, it must undergo a process known as malting. The malting process simulates the grain's natural germination cycle. Under closely monitored conditions, malting companies wet the barley kernels and allow them to sprout. As the seedlings begin sprouting, the starchy insides of the kernels (or endosperm) begin to change. This modification causes the hard, starchy endosperm to begin to break down into natural malt sugars (maltose) that brewers later liquefy, during the mashing process. One of the important features of this process is the production of the enzymes brewers later use in the mashing process. And the maltose sugars, along with proteins and dextrins, contribute the color, flavor, sweetness, body, mouthfeel, and foam in the beer. (Mouthfeel can be defined as the textural qualities of beer on your palate and in your throat — viscosity, or thickness; carbonation; alcohol warmth; and so on.)
Only after the barley has undergone the malting process does it become malt, or barleymalt.
Malted barley is an incredibly complete and convenient package, seemingly designed exclusively for brewing beer. Each grain kernel contains carbohydrates (which eventually convert to sugar), enzymes (which do the actual converting), proteins (which provide yeast nutrition, mouthfeel, and head stability), and a husk (which, when multiplied by thousands, acts as the perfect natural filter bed through which you can drain the unfermented beer).
Very few commercial brewers — usually only the huge beer factories — do their own malting. Professional malting companies (also called maltsters) malt most of the grain for the brewing industry (including smaller commercial brewers and homebrew supply shops).
In order to make beer from the malted grain, the starch within the kernels of malt must be made soluble. This liquefying process takes place during the mashing procedures in a vessel called a mash tun. The mashing process is where the natural enzymes found in grain break down the grain's starches; hot water then dissolves the starches so they leach out of the cracked grain. After you've rinsed all the malt sugars from the grain, you transfer the syrupy-sweet malt tea, called wort, over to the brew kettle, where you boil it. Homebrewers who make their beer with malt extract can avoid the mashing process altogether.
Wort (rhymes with dirt) is the German word for unfermented beer. Some brewers also call wort green beer (and not just on St. Patrick's Day).