Malted or unmalted grain that must be mashed (base malt, flaked adjuncts).
Crystal/roasted malt whose extract is available without conversion.
Dry malt extract (DME).
Liquid malt extract (LME).
Simple sugar the yeast ferments essentially completely (sucrose, dextrose, honey).
Dissolves and raises gravity but the yeast cannot touch it (lactose, maltodextrin).
How a fermentable behaves in the brewhouse and in the fermenter.
The class drives two defaults: the extraction efficiency that applies to it (
graingets mash efficiency,steeping-graina partial efficiency, everything else 100 %) and how much of its extract the yeast can consume (see FermentableAddition.fermentabilityPercent).