The invention relates to an aqueous enzymatic method for preparing 
protein peptide powder from soybean 
hydrolysate and belongs to the technical field of 
soybean product processing. The method comprises the steps as follows: (1) soybeans are peeled and crushed, 
extrusion treatment is performed, and an extruded product is obtained; (2) water is injected into an 
enzymatic hydrolysis reaction tank, 
steam heating is performed, the extruded product is added, a 
mixed solution is obtained, the pH value of the 
mixed solution is adjusted, and 
alkaline protease is added for enzymolysis; (3) 
centrifugal separation is performed with a horizontal 
centrifuge after enzymolysis, and 
emulsified oil, a 
hydrolysate I and residues I are obtained; (4) 
isolated soy protein is added to the 
hydrolysate I, the pH value is adjusted, 
pepsin is added for enzymolysis, 
centrifugal separation is performed after enzymolysis, 
soybean oil, a hydrolysate II and residues II are obtained, alkali is added to the hydrolysate II for 
neutralization until the pH is neutral, and 
desalination is performed with an 
ultrafiltration membrane; (5) malt syrup, 
maltodextrin and other auxiliary materials are added to desalinated hydrolysate for blending, uniform mixing is performed, a 
protein emulsion is formed, homogenization, vacuum concentration and 
spray drying are performed, and 
protein peptide powder is obtained. The method adopts a simple process and is low in cost, the prepared protein 
peptide powder has high nutritional value, has strong milk 
aroma, tastes fine and has good digestibility, besides, the instant 
solubility of the protein peptide powder is significantly improved, and the protein peptide powder is suitable for industrial 
continuous production.