Water starch is dry starch with water, which together is called water starch, also called wet starch. Starch is divided into corn starch, sweet potato powder, mung bean starch, white powder, cassava powder, Ge Fen and so on. Dry starch is usually used for frying things, or dry starch is added to egg liquid. Starch used for thickening, also known as dough powder, is a polysaccharide polymer concentrated by multiple glucose molecules. Cooking starch mainly includes mung bean starch, potato starch, wheat starch and lotus root starch.

Starch is insoluble in water, and when heated to 60C with water, it will be gelatinized into colloidal solution, which is the purpose of starch. Due to the treatment of pulp, flour, paste, juice and glutinous rice flour, it can also play the role of a protective layer, which not only prevents the loss or destruction of nutrients, but also avoids unhealthy substances produced by the contact of animal protein with high-temperature paste. There are generally two methods for thickening. One is starch juice with seasoning, commonly known as "juice-to-juice", which is mostly used for dishes cooked by quick frying and stir-frying. The other is simple starch juice, also called "wet starch", which is mostly used in general cooking.