China is the world's major fishery production country. According to statistics, small miscellaneous fish and low value fish account for 50% - 60% of the marine fishing output. At present, the processing rate of aquatic products in developed countries is more than 80%, while that in China is less than 30%, of which the processing rate of freshwater fish is less than 10%, and the by-product output of freshwater fish in China is more than 2.5 million tons per year. In the process of fish processing, a large number of leftovers (including fish head, internal organs, skin, fins, scales, tail, bones and residual fish meat) will be produced. The weight of the leftovers accounts for 40% - 55% of the raw fish. If not treated effectively, it will not only pollute the environment, but also waste a lot of nutrients. At present, the utilization of these leftovers is mainly used to produce fish meal in China, but the valuable ingredients have not been fully utilized.

Fish scraps are treasure all over the body

Fish offal includes fish head, tail, minced meat, gall, bone, scale, viscera, skin, etc. it contains a lot of protein, amino acid, trace elements and vitamins. Using this protein resource, we can make a variety of deep processing products, including soluble edible fish protein powder, liquid fish protein feed, fish scale glue, fish skin glue, fish bone paste, fish protein calcium sugar, bile pigment calcium salt and bile acid salt. Among them, the protein is the focus of the development and utilization of fish offal. The fish protein has a very high grade, the proportion of amino acids in it is very close to the composition of human muscle, and the absorption and utilization rate is high. It can be used as the base material of amino acid fortified food, milk powder substitute, nutrition soup, seasoning and fish protein beverage products. Soluble edible fish protein is an effective drug for the treatment of diarrhea caused by dyspepsia in children. It can also be used as a protein source in the feeding fluid of patients with cancer or eating difficulties after surgery.

At present, the processing methods of fish protein are mainly acid-base method, biological enzyme method. Compared with acid-base method, enzyme method has mild reaction, no carcinogenesis of hydrolysate, and low environmental protection pressure in the later stage of production, which is the main direction of fish protein processing. Through the special enzyme for hydrolysis of seafood (mainly composed of endonuclease, exonuclease and flavoring enzyme), the product can be used to hydrolyze all kinds of animal protein at a certain temperature and pH value, so as to control the degree of hydrolysis of animal protein to achieve the decomposition of macromolecular protein, thus obtaining the required polypeptide, small peptide and amino acid products, so as to achieve the yield, solubility, flavor and taste of the product To the new product level. It can be widely made into various high quality food industrial raw materials and feeds.