While long fermented traditional doughs allow lots of time for enough starch to break down into the sugar for the yeast to feed on; in modern bread, Alpha Amylase is included in bread improvers to make the process faster for commercial enterprises.
When making bread commercially, yeast is given either sugar, or sugar that results from Alpha Amylase acting on the starch in the flour. Some argue that industrially, alpha amylase is better than sugar because it releases sugar energy at a rate proportional to the rate that the yeast needs it. But the alpha-amylase damages the flour, by breaking it down to get the sugars out. Consequently, flour that has alpha-amylase act upon it holds less water, so more flour must be used, thus pushing the baker's cost up.
Using too much Alpha Amylase in a bread dough can make the dough sticky (as it hasn't been able to absorb enough water), and can lead to undesirably large gas-caused holes in the bread, because the yeast was too active. The resultant crumb will also be somewhat sticky and harder to slice.
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