β-Amylases

Enzymes classified as EC 3.2.1.2 that hydrolyse 1,4-α-glucosidic linkages from the non-reducing ends of starch chains, releasing maltose unit by unit. They are exo-acting partners to the endo-acting α-amylases: α-amylase creates new chain ends and β-amylase harvests them as maltose. Malt is rich in β-amylase, which is why mashing converts starch so efficiently into fermentable maltose for brewing and distilling. In baking, β-amylase boosts fermentable sugars for yeast, improving volume and crust colour. They cannot pass α-1,6 branch points, leaving limit dextrins that need debranching enzymes. Their activity is a key malt specification, and kilning must be controlled to preserve it.