The amylases are a group of enzymes that break down starch, which is made of long chains of molecules, into sugars composed of much shorter chains. The amylases exist in three forms, labelled α, β, and γ, collectively known as diastase.

Yeast can only metabolise glucose, so it relies on the action of the amylases to break the starch down into glucose and another sugar called maltose. Maltose is further broken down by the enzyme maltase to produce glucose. The yeast can then convert the glucose into energy, and produces carbon dioxide and ethanol as waste products in the process known as fermentation.

Amylase occurs naturally both in flour and yeast

Want to find out more? Look at the chapter on rising, proving and fermentation in the book flour and water.

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