China is the country with the largest output of aquatic products in the world, and the only country in the world where the amount of fish caught exceeds catch. However, for a long time, freshwater fish processing has been very weak, which has restricted the development of freshwater aquaculture. With the introduction and breeding of quality freshwater fish, the output of freshwater fish will further expand. It can be foreseen that if the freshwater fish processing and utilization channels are not expanded, the price of freshwater fish will decline further in the current situation.
1 The use of freshwater fish and fish meat The analysis of the various components of freshwater fish and marine fish muscles shows that the difference between the two is not obvious, that is to say, from the point of view of nutritional function, freshwater fish can replace seawater fish without any problems. General freshwater fish fillets account for about 50% of the total body weight of fish, which is currently the highest utilization rate and the most valuable part. Its processed products include:
1.1 Freshwater fish frozen fish and fish products China's scientific research and production units and international cooperation agencies have done a lot of work on frozen fish fillets and surimi products processing of freshwater fish. Through years of research, we have completed the assessment of the quality of seven kinds of freshwater fish surimi that are equivalent to more than 80% of China's freshwater fish production. The result is that freshwater fish, like marine fish, have different gel properties in fish gills of different fish species, but overall, higher yields of chain fish, sea fish, grass carp, and slightly lower yield tilapia It is perfectly suitable as a raw material for frozen fish gizzards.
The basic process for producing frozen fish roe or surimi products from freshwater fish is as follows: Raw fish i pre-treatment i Roast i rinsing i Dewatering i Fine filtration i Flavors i Molding i Molding. Gelled i Heated i Package i Frozen i Finished product
The raw fish is first cleaned to remove surface stains, then the head is removed and the blood is washed again with clean water. The use of meat-measuring machines for meat-recovery generally does not require too high a meat-recovery rate for freshwater fish, and the gel properties of fish-meat are generally inversely related to the meat-collection rate. The collected fish meat is rinsed with a rinsing solution to remove most of the water and dissolve the protein. After dehydration and fine filtration, it is collapsed using a teasing machine. In China, there are also smashing machines using a squeezing machine. Has little effect. It is recommended to use a vacuum rake or a vacuum squeezing machine. The product thus obtained has a uniform texture and does not contain large bubbles. It is also stable during the subsequent storage and does not easily undergo discoloration or odor. In the entire process, gelatinization of surimi products is the most important step, and now generally two-stage heating method is adopted, that is, first placing at a relatively low temperature (30.40Y) for a long time, and then curing at a high temperature.
The surimi products are less affected by the type of fish, body size, and tissue structure in the selection of raw materials. Different types and sizes of fish can be used together. The use of surimi as a raw material to produce high-value-added artificial crab leg meat and simulated shrimp has a large sales market in the international market, and it is also an important development direction of surimi products.
1.2 Development of snack food Freshwater fish and fish can be developed into a variety of snack foods, such as fish sauce, fish fillets, fish fillets and other products.
The simple process for processing snack foods (fish) with freshwater fish is: freshwater fish i cooking i cooking i dehydration i adding auxiliary raw materials i frying i moulding i baking i cooling i packaging i sterilization i finished products
Fish pellet food is a kind of high-protein, low-fat delicious snack food. Currently, it has a large sales market in Hong Kong, Macao and Southeast Asia. With the improvement of the living standards of our people, the consumption of snack foods will also increase substantially. It is expected that there will be great development in the control of the ingredients added with excipients, adding the nutrients needed by the human body, and processing them into fortified foods or health foods, especially those developed for children with nutritional imbalances and childhood obesity.
Freshwater fish snack foods In addition to fish, there are fish, fish fillets, grilled fish fillets, fish rolls, fish skewers and other products.
1.3 Preparation of Fish Protein Concentrates Since fish protein itself is an excellent protein source, its utilization in the human body is higher than that of normal plant proteins, livestock products, etc. Therefore, freshwater fish is used as raw material to produce concentrated fish protein or fish protein skin. , as a protein enhancer or flavoring filler has a better application effect.
The concentrated fish protein has been studied in many countries in China, including solvent extraction method, enzymatic method, and acid-base hydrolysis method. Due to organic solvent extraction methods, there are many problems with the residual or recovery costs of organic solvents, and research is rarely used now. Similarly, except for the preparation of feed fish protein, the acid-alkali hydrolysis method is not a lot of applications. Now the general processes of dew hydrolysis used and studied are: Raw fish i Pretreatment i Meat extraction i Minced enzyme Hydrolysis i Methanol i O Oo Bitter i Condensation i Dry i Cooling i Weighing i Packaging i Finished products
In the process of enzymatic hydrolysis of fish protein concentrates, the type and amount of enzymes, the conditions of enzymatic hydrolysis, etc. will affect the taste and color of the product. Due to the hydrolysis, the exposure of sulfuric amino acids, the production of bitter taste ribs will make the product There is a certain amount of bitterness. It is reported that the production of bitter ribs has a greater relationship with the degree of hydrolysis. How to control the production of bitter taste ribs and how to mask bitterness are more common research subjects in scientific research institutes.
2 Fish heads and fish bones The use of freshwater fish has a relatively large head, which often accounts for 24% of the total fish body weight. 34%, so the treatment of fish heads is not only related to the price of the product, but also has a huge impact on the environment. Although the taste of freshwater fish is often worse than that of marine fish, the fish head has a better flavor. The price of certain freshwater fish heads in the market is higher than the price of fish meat. As a nutritional tonic, freshwater fish head has a long history in China. There is a saying that “one fish head and three moneysâ€.
First of all, the fish head is rich in lecithin, EN, and DHA, both of which have significant effects on the development of children's brain and prevention of dullness in the elderly. In terms of fish heads, the content of EPA and DHA in their fats was 6.37% and 7.29%, respectively, while the content of unsaturated fatty acids in sardines, tuna, and red mullet in saltwater fishes was 1. .7%, 1.3%, 1.2%.
2.1 Use fish head fish sound to produce flavor substances
By using the better flavor of the fish head, the flavoring substances can be made by cooking, enzymolysis, reaction, filtration, etc., and can be directly used as a seasoning, or can be added into soy sauce and chicken essence to make a composite seasoning. The basic process is as follows: raw fish head d is washed and rinsed, 6Eg is hydrolyzed with dynamic D protease/washed i dehydrated i dried fishbone powder autoclave i filter/filtrate i centrifugal i hydrolyzate i concentrated dried/fish oil finished The process is a basic process for preparing fish bone powder and fish head flavors. Hydrolysis odor and bitter taste ribs are also produced in the preparation of hydrolyzed fish heads, and the hydrolysis process is controlled by adjusting the type of protease, the amount of enzyme added, the process conditions of enzymatic hydrolysis, and the ratio of feed to liquid, etc.; A blending process, adding other flavoring materials, strengthening the Merak reaction and other means to make the final product taste, flavor coordination; in the process of concentration and drying, in order to reduce the loss of flavor substances in the storage process, increase the shelf life of products using microencapsulation Methods.
2.2 Fish sound powder processing technology The fish bone powder refers to the fish bone powder prepared with the bone of freshwater fish. The basic process is: bone cleaning in fish i minced i cooking i's trepidation Jiang Lei Lei Yihui Fluror II %0.a9m Shanghai Aquatic Products Processing Technology Development Center and Shanghai Donghai Pharmaceutical Factory conducted animal experiments and pregnant women clinical trials on fish bone meal prepared according to the above process, which proved that this product is highly active in supplementing human calcium. , achieved the desired effect.
3 Processing and utilization of fish scales
During the production and processing of fish products, fish scales, internal organs and other leftovers are produced. This part of the leftover material accounts for 10% of the total weight of the fish. 15%. Fish scales have long been used as medicine records in China. They have nourishing yin and nourishing blood, reducing serum total cholesterol and fermenting enzymes and triglyceride function. They can replace the rare source of turtle gum and have an efficiency of over 95%.
3.1 Collagen Extraction Collagen is the most abundant protein in fish scales. Collagen extraction process is as follows: Fish scale raw material i Cleaning i Acid treatment i Alkali treatment i Cleaning i Buffer solution Extraction i Separation i Purification i Dry i Finished product
The raw fish scales obtained are first cleaned, soaked in a dilute hydrochloric acid solution to remove inorganic ions from the fish scales, and then soaked in a weak lye. After washing out, wash with water to neutrality, leaching with different types of collagen extract (obtaining different types of collagen), immersing, purifying, and then low-temperature drying. If the product is used for cosmetic or pharmaceutical fillers, it should be noted that the drying temperature, preferably by lyophilization; if used as a supplement or food additive, the drying temperature requirements can be relaxed. Some studies of pepsin can increase the solubility of collagen, but do not exert any hydrolysis on collagen. If this method is feasible, it can replace the long-term alkali treatment.
3.2 Preparation of Fish Scale Solution The proteins in the scales are proteolytically hydrolyzed, and the prepared hydrolysate can be used for the production of condiments and functional food additives. The basic process is: Raw fish scale i pretreatment i Acid treatment—4 Wash - 4 plus enzyme hydrolysis i inactivated enzyme. Separation i Concentration i Coagulation — 4 Sections — 4 Drying — 4 Finished Addition of different types of proteases hydrolyzes collagen macromolecules in fish scales to obtain polypeptides and free amino acids with a low degree of polymerization. First, some free amino acids and the short skin itself have a taste effect, and the hydrolyzate can be used as a raw material for seasonings. In addition, during the hydrolysis process, functional skin with specific functions is also produced. It has been experimentally proved that fish scale hydrolysate has the effects of anti-oxidation and lowering blood pressure, lowering total blood cholesterol, anti-aging and the like.
4 Conclusions China has abundant freshwater fish resources, but due to its small spurs and difficult to remove, the processing difficulty is greater than that of the currently used marine fish. At the same time, freshwater fish are inevitably soiled because they grow in ponds or lakes.腥昧 and other shortcomings. At present, the utilization rate of freshwater fish is very low, the processing volume is less than 2%, and the weak links in freshwater fish processing have restricted the development of freshwater aquaculture.
The first step is to increase scientific research and resolve various technical problems in processing as soon as possible, which is the prerequisite for the full processing and utilization of freshwater fish.
Second, the introduction of high-quality freshwater fish resources should be bred. For example, tilapia, which is currently bred in Guangdong, has become the largest freshwater fish species after the white chain. With the emergence of good fish species, its processing performance will be greatly changed.
Thirdly, it calls for the active participation of enterprises. As fishery products companies mainly use marine fish as the main raw material, there is very little use of common freshwater fish in China. Therefore, there is a need to have a strong enterprise to play a leading role in the market. As long as a fishery product company uses freshwater fish as its raw material, it is easy to develop into a related company due to the advantages of freshwater fish prices.
Fourth, the government plays a guiding role. At the same time, it promotes and guides the development of the freshwater fish aquaculture industry and changes the traditional concept that the freshwater fish cannot be processed.