Malt is partially germinated barley, which has been dried afterwards. The first step in brewing beer is to convert crude barley grain into crumbly malt which is rich in enzymes. The conversion is done by germination, which releases the starch granules of the grain and produces enzymes (diastases). The latter convert starch into sugar. The quantity of malt used is directly proportional to the degree of alcohol the beer is expected to have.

Barley is the most frequently used cereal for brewing. It is, however, not the only one:  corn, rice or wheat can be added to give the beer the desired flavor.

Malt by BrewDog