In order to improve the performance of starch and expand its application range, physical, chemical or enzymatic treatment is used to introduce new functional groups on starch molecules or change the size of starch molecules and the properties of starch granules, thereby changing the natural characteristics of starch (such as gelatinization temperature) , Thermal viscosity and its stability, freeze-thaw stability, gel strength, film-forming properties, transparency, etc.), making it more suitable for certain application requirements. This kind of starch that has undergone secondary processing and changed its properties is collectively referred to as modified starch.