Before grain can be used to make beer, the starches stored in the kernel must be converted to fermentable sugars. The grain does this naturally as part of the germination process, so the brewer need only harness this process and then stop it before the grain sprouts to capture the sugars they need for their beer. This controlled germination is called malting (from the Dutch moute: to soften).
Typically, a farmer would take his grain harvest to the mill so that it can be ground into flour and sold. In an economy short on specie money (hard currency), the miller was generally paid with a portion of this grain rather than in cash. Since the miller easily accumulated far more grain than they needed and since alcohol sales were largely cash transactions, the miller often sold this grain, for specie money, to a maltster who malted and roasted the grain for brewing. Sometimes brewers and distillers ran their own malt houses but since the process is labor intensive, malting was often a specialized trade. Samuel Adams was a maltster, not a brewer, in Boston.
The malting process is basically as follows:
- Grain is carefully washed to remove any dirt or other impurities from the harvesting and threshing. This is important because after it is malted, removing these impurities will reduce the brewing yield of the malt.
- The grain is then soaked in a deep vessel for 2-3 days in clean water. This allows moisture to fully permeate the grains. We know the grain is sufficiently soaked if it can be gently crushed between finger and thumb.
- The grain is then transferred to a warm, not hot, malting hutch and allowed to germinate for 2-3 days in deep piles. After 48-72 hours, the conversion should be complete, and the malt is ready to dry.
- Malted grain is now spread in a thin layer on the malting floor or screen and allowed to dry. Constant effort is taken to rake and turn the malt so that it dries evenly and quickly.
- After about a day, heat or smoke is introduced in order to arrest the malt germination. This heat is gradually increased over the course of a day until the malt is fully dry and hard.
- Malt is then roasted in a shallow pan at high heat. The degree of caramelization that occurs during this roasting process will determine the beer’s final color (Lovibond scale). High Lovibond grain produces dark beer and low Lovibond produces blonde beers.
- Immediately before use, the roasted grain is crushed, not ground into flour, between wooden rollers to allow access to the kernel’s sugars.
Malt made in this manner can then be used to make beer or whiskey.