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Alpha‐amylase is a naturally occurring enzyme that breaks down starch to release sugars during seed germination. Some α‐amylase is beneficial for breadmaking because the sugars released are required for fermentation. In fact, commercially produced enzyme may be added as an improver in commercial breadmaking. However, excessive activity results in a dark crust (due to Maillard reactions) and a sticky crumb with poor resilience and texture, the latter preventing the use of mechanical loaf slicing (Chamberlain et al. 1982).

Excessive α‐amylase can result from several syndromes, three of which come into play early in grain development (Lunn et al. 2001). These are the retention of high levels of α‐amylase in the pericarp (retained pericarp α‐amylase activity, RPAA), the deposition of specific α‐amylase isoforms in the endosperm cavity during grain development (pre‐maturity α‐amylase activity, PMAA, or late maturity α‐amylase, LMA) and, very rarely, the germination of the grain early in development (pre‐maturity sprouting, PrMS). However, by far the most common syndrome is germination (sprouting) of the mature grain before harvest, i.e. pre‐harvest sprouting (). This occurs when the crop is subject to wet conditions just prior to harvest, and when the grain has low levels of dormancy.

Levels of α‐amylase are assessed using the Hagberg Falling Number (HFN) test. This was initially developed to monitor the levels of α‐amylase in wheat growing in the field in Sweden to decide whether the crop was at risk of spoilage. It is now widely used by the grain industry as a measure of α‐amylase activity in harvested grain. HFN is a measure of the viscosity of a mixture of water and milled wheat mixed in a tube and placed in a water bath at 100 °C. Alpha‐amylase breaks down the starch and, therefore, reduces the viscosity of the water: wheat mixture. The falling number is the time in seconds required for stirring (60 seconds) plus the time taken for a stirrer to fall through the flour suspension while it is being liquefied by the enzyme (Vaidyanathan 1987).