Raw starch is often stored in seeds, tubers, leaves and dried fruits of plants in granular state, which is a storage form of plant nutrients. Different crops have different starch content and characteristics due to different varieties, climate, soil and other conditions. Raw material fermentation refers to the process of direct saccharification and fermentation of raw starch without cooking and gelatinization. The hydrolysis and saccharification of raw starch granules are the same as the enzymatic hydrolysis of gelatinized starch by amylase, that is, A- 1, 4 glycosidic bonds and A- 1, 6 glycosidic bonds are hydrolyzed from non-reducing ends and converted into glucose. However, due to the different existing states of the two starches in water, their action modes are also different. After starch is gelatinized by heat, the water bundle layer on its surface is destroyed, so that water molecules can penetrate deep into the starch molecules, and the starch molecules are in a loose state in water, so that the enzyme can easily approach the starch molecules and cut off its glycosidic bonds; However, due to the repulsion of the surface water beam layer, the water molecules of native starch cannot penetrate through the water beam layer into the starch molecules, and the starch molecules are relatively dense in water due to hydrophobic interaction, which makes it difficult for the starch molecules to get close to the enzyme molecules. Therefore, whether the enzyme can combine with the surface of raw starch particles is the key to hydrolyze raw starch. Only glucoamylase which can be adsorbed by raw starch has the ability to hydrolyze raw starch. Whether raw starch glucoamylase can be combined with raw starch and the degree of combination depends not only on the composition and order of amino acid residues of the enzyme molecule itself, but also on the starch of the enzyme affinity site. Because of its different source activity, glucoamylase has different hydrolysis degree to raw starch. Starch itself has a certain adsorption capacity, and its adsorption capacity is related to the source and existing mode of starch. Generally speaking, the higher the starch content, the better the adsorption and hydrolysis. In a word, the hydrolysis process of raw starch glucoamylase is: adsorption; Forming an enzyme-starch complex; The water beam layer on the surface of starch in the complex was destroyed, and water molecules entered the starch molecules and hydrolyzed glycosidic bonds under the action of enzymes.