In Exchange Rates I and Exchange Rates II, we discuss how to treat base malts and specialty grains when converting an all-grain recipe to an extract-based formulation. In an ideal world, malt extracts would all be made from 100 percent base malt, but this is rarely the case. Most malt extracts are produced using a blend of one or more base malts and some specialty grains, and the precise formulation varies from one manufacturer to the next.
The following table indicates the typical ingredients found in the most widely available malt extracts in the United States. Percentages are provided where possible. This list is not exhaustive, and you should ask your suppliers to provide information on the particular brands of extract they sell.
Liquid malt extract ---> Typical composition