when the water temperature is above 53℃, starch will swell and split in the solution at high temperature to form a uniform paste solution, which is called starch gelatinization. Saccharification is the process that starch is decomposed into sweet products by adding water. It is the main process in the manufacturing process of starch sugar products. It is also the main process of many intermediate products in food fermentation. Starch liquefaction: In fact, starch changes from high molecular state (starch granules) to low molecular state (dextrin) under the action of alpha amylase, and the viscosity of starch decreases, that is, it changes from semi-solid state to solution state. The starch was heated in water bath and stirred continuously, and the starch paste was gradually gelatinized. After gelatinization, α -amylase was stirred continuously at 7~8℃ to liquefy it, and the enzyme was inactivated and filtered. The filtrate was cooled and saccharified with saccharifying enzyme at 6 ~ 65℃.