Method for preparing hairtail polypeptides

The invention relates to a preparation method of hairtail polypeptide, including the following steps: (1) putting hairtail in water which is 1 to 3 times of the weight of the hairtail and wringing the hairtail and the water evenly into fish meat pulp; (2) putting the fish meat pulp in an enzymatic vessel, raising the temperature to 45 DEG C-65 DEG C and regulating the pH value to 5.5-8.5; in the weight of the hairtail, adding endoprotease of 1.0-3.0 percent and nisin which is 0.02-0.1 percent of the weight of the fish meat pulp weight at the same time; implementing the agitation hydrolysis on the mixed fish meat pulp for 16-24h; adding the endoprotease of 1.0-5.0 percent, regulating the temperature to 45 DEG C-60 DEG C, regulating the pH value to 5.0-8.0 and keeping on the agitation hydrolysis for 3-6h; (3) killing enzyme; (4) centrifuging to fetch supernatant; (5) decompressing, concentrating, vacuuming and drying the supernatant to obtain a hairtail polypeptide product. The molecular weight range of the hairtail polypeptide obtained through the method is kept within 250Da-6000Da; the content of the polypeptide, the molecular weight of which is smaller than 1000Da, is higher than 50 percent.