Application of neutral protease in the production of fish scale collagen peptides

my country is rich in water resources. A lot of scraps are produced in the production and processing of fish products, of which about 15% are fish scales. According to incomplete statistics, 300,000 tons of fish scales are discarded in my country every year. The protein content in fish scales is as high as 50%-70%, which is a very good biological resource. Fish scales are deformed products of the fish dermis, accounting for 3% to 5% of the total weight of the fish body. They are rich in protein and minerals. Among the organic matter of 41% to 55% of the total weight of fish scales, more than 90% are collagen and fish scale hard protein.
The preparation methods of fish scale collagen peptides mainly include chemical hydrolysis and biological enzyme hydrolysis. The former is to hydrolyze collagen with acid or alkali. Although the method is simple and low in cost, the hydrolysis process can destroy amino acids, resulting in large nutritional losses, complex products, and a lot of wastewater, and the production cycle is long; the latter is to extract by destroying the original structure of the extract through the enzyme cutting site; it has the advantages of high hydrolysis efficiency, mild conditions, and easy control of the hydrolysis process. In the pretreatment of fish scales, attention should be paid to the removal of ash (hydroxyl scale limestone).

Using defatted and de-ashed fish scales as raw materials, using neutral protease for enzymatic hydrolysis can obtain more amino acids; strong hydrolysis and high yield; neutral protease can well hydrolyze fish scale protein into 500-3000Da peptides, which are suitable for the needs of the food and cosmetics industries. Bio-directed enzymatic hydrolysis technology and membrane separation technology are used to extract, separate and purify peptides respectively, and high-performance liquid chromatography is used to determine the molecular weight and amino acid sequence.
Generally speaking, the smaller the molecular weight of collagen peptides, the easier it is to be absorbed by the human body. However, when the molecular weight is too small, the structure of collagen peptides is easily destroyed and the function is relatively affected. Even if it is absorbed by the human stomach and intestines, it can only achieve the function of supplementing the corresponding amino acids. Compared with the violent acid method and alkali method, the mild and controllable enzyme method further demonstrates its advantages.