Barley and Malt
Barley is a basic cereal grain not particularly good for milling into flour and making bread or bakery goods. But it is great for beer. There are three major types of barley. These are differentiated by the number of seeds at the top of the stalk. Barley seeds grow in two, four and six rows along the central stem. European brewers traditionally prefer the two-row barley because it malts best and has a higher starch/husk ratio than four or six-row barley. Brewers in the US traditionally prefer six-row barley because it is more economical to grow and has a higher concentration of enzymes needed to convert the starch in the grain into sugar and other fermentables.
Malting: Barley must be malted before being used to brew beer. Malting is a process of bringing grain to its highest point of possible soluble starch content by allowing it to sprout roots (germinate) and take the first step to becoming a normal, photosynthesizing plant. It is at this point that the seed is rich in the starch it needs to use as food for growth. Then, the maltster heats the grain to a temperature that stops the growth process but allows a natural enzyme, diastase, (which converts starch into sugar or maltose) to remain active. It is this sugar or maltose that the yeast metabolizes into carbon dioxide and ethyl alcohol. Some of the malted barley is or can be heated at a higher temperature to roast it. The roasted malted barley no longer has the active enzymes needed to turn the starch into sugars, but does impart characteristics that add flavor to the beer. The degree of roasting determines the color of the beer and the greatest roasted malted barley will impart its roasted flavor to the beer.