alpha-amylase turns starch into dextrins - a process sometimes called dextrinization. Dextrins (3-4 glucose molecules bound together) can be further split into glucose by other enzymes.
As temperature goes up two things happen in enzyme reactions:
1. every 10 degrees C increase means the enzyme works approximately
twice as fast.
2. proteins denature with heat - like an egg white hitting a hot frying pan. Egg white is protein. alpha-amylase is a protein. As temperature goes up you risk denaturing amylase, turning it into useless glop. There is a temperature at which the amylase's activity stops because the protein denatures too fast to have any effect. This is also why boiling water kills living things, like many kinds of bacteria, fungi, and yeast.
149-153 F (65-67 C) is usually considered to be the highest temperature for
rapid dextrinization. Higher temperatures, above 67 C, denature the enzyme too fast, the temperature "kills it off" so to speak - before it can do it's job.
Is this what you mean?
