An adjunct is any substitute fermentable ingredient added to the mash.
There are generally two purposes for adjuncts:
- to reduce costs by including cheaper fermentable sugars
- to add or reduce flavor and/or body
The very large brewers of industrial light lagers are (in)famous for the first, but the palates of the vast majority of beer drinkers prefer the lighter flavor and body of these lagers, which is generally achieved using rice or corn.
Adjuncts can also enhance flavor. Oatmeal stout, for instance, has oatmeal as an adjunct, which gives that brew its distinctive smoothness. Fruit beers (not lambics) such as Southern Tier Raspberry Porter have fruit and/or fruit extracts added during some portion of the brewing process.
Common non-malted grain adjuncts:
- corn (maize)
Some non-grain adjuncts:
- brown sugar
- herbs and spices
- maple syrup