Processing and preservation of the hottest crustac

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Processing and preservation of crustacean aquatic products. There are not only a large number of marine shrimp and crabs, but also a large number of freshwater shrimp and crabs. With the continuous improvement of people's living standards in China, great changes will take place in the dietary structure. The proportion of animal food will be larger and larger, and the proportion of aquatic products in animal food will also be larger and larger. This situation provides a good opportunity for the water supply product processing industry to leap to a new level

the traditional products of shrimp and crab processing in China are mainly frozen shrimp, crab and dried products. In recent years, shrimp and crab processing and preservation have made great progress, and the products are becoming more and more diversified. It is summarized as follows

1. Research progress in shrimp processing and preservation

shrimp meat has high nutritional value. Its average protein content is 17.8%, fat content is 1.3%, and it also contains a variety of amino acids. Shrimp extract contains a large amount of betaine, arginine and other components, which has a unique flavor. However, the freshness of shrimp decreases rapidly, and it is easy to blacken and soften, which makes it difficult to process and preserve shrimp

1.1 shrimp processing

1.1.1 raw materials: before shrimp processing in China, shrimp, Penaeus penicillatus The experimental results of the short ditch shrimp waw (6) 00g/1000g electro-hydraulic servo special experimental machine for prestressed steel strand can be queried and printed (the force displacement, Penaeus monodon, Penaeus japonicus, and Chinese hairy shrimp, Japanese hairy shrimp, lobster, and Japanese coastal shrimp are used as raw materials. In recent years, with the relative reduction of shrimp resources, people have developed new resources. On the one hand, the discovery of Antarctic krill, with an annual catch of up to 50-100 million tons, is known as "Animal protein warehouse"; On the other hand, with the great development of breeding and aquaculture technology, freshwater shrimp also accounts for a considerable proportion; In addition, the marine capture of low value shrimp has also been greatly applied, which has opened up a good development prospect for the processing of aquatic shrimp in China

1.1.2 new shrimp processing products: at present, in addition to the original frozen and dried products, shrimp processing varieties have also developed several new products: block frozen cooked and single frozen cooked stung shrimp meat made of whole krill (commonly known as freshwater lobster) through cooking, shelling, quick freezing and other processes; Live shrimp exported to Japan produced by low temperature and cold shaving ice storage; The frozen seafood cake is made by taking shrimp meat and frozen surimi as the main raw materials, adding salt, adding seasoning, quality improver and other auxiliary materials to mix evenly, forming a cake through the fish cake forming mechanism, gel packaging and quick freezing; Using the special ingredients of Antarctic krill (as full price protein and containing high unsaturated fatty acids) to make functional food; As well as the use of low-value marine shrimp processed into rare roasted shrimp

1.2 shrimp preservation methods: the general shrimp preservation technologies are low-temperature preservation, such as ice preservation, cold sea water preservation, micro freezing preservation, etc. these technologies have been widely used. But there are also some defects. With the development of modern technology, people have studied several new preservation methods

1.2.1 low temperature storage and transportation method: low temperature storage and transportation method is the most widely used and simplest method for keeping fresh and alive. According to the purpose and temperature of low-temperature preservation, it can be divided into ordinary low-temperature preservation, vitrification transfer preservation, ultra-cold preservation and so on. Ordinary low-temperature preservation can be divided into ice preservation, cold seawater preservation, micro freezing preservation, freezing preservation, frozen preservation, etc. When using this method to store and transport shrimp, gradually cool the shrimp to a suitable temperature, and then keep it at a certain temperature, which can be stored and transported for a long time. The method is economical and effective

1.2.2 oxygen method: the method of transporting live aquatic animals with hyperoxia in plastic bags has been applied, and it can also be used in the preservation of shrimp. First add 1/4 of water into the plastic bag, put the shrimp in the old man's bag, exhaust the air, and then charge oxygen for sealing. The volume ratio of water to oxygen in the bag is 1:3. If the method is appropriate, a better survival rate can be obtained

1.2.3 ozone water method

the main Shenwan Hongyuan of ozone water as an oxidizing bactericidal preservative told an analyst who did not want to be named that if its strong oxidizability was used. Ozone water can quickly penetrate into bacterial somatic cells, denature proteins, destroy enzyme system, and kill bacteria. Its sterilization speed is 300 to 1000 times that of chlorine; Moreover, after ozone is decomposed in water, it will not form residues in products, affect the flavor of products, and will not cause pollution to the environment. Adopting ozone water dynamic sterilization treatment (spray sterilization method) can achieve better sterilization and fresh-keeping effect, and make the products meet the export requirements of high quality, safety and sanitation

1.2.4 anesthesia: this method uses anesthetics to inhibit the central nerve of shrimp, so that it loses its reflex function, reduces the intensity of respiration and metabolism, and achieves the purpose of keeping alive. The operation method is simple, and the shrimp can be quickly revived after being put into clean water. At present, the anesthetics that have been used mainly include MS-222, procaine hydrochloride, benzocaine hydrochloride, carbonic acid and carbon dioxide, ether, zanatine, urethane, frasidil, trichloroacetic acid, etc

1.2.5 enzymatic method: use the catalytic effect of enzymes in gb4857.3.4 to prevent or eliminate the adverse effects of external factors on shrimp, so as to maintain its original good quality. At present, glucose oxidase and lysozyme are widely used. On the one hand, it uses the gluconic acid produced by its oxidation of glucose to reduce the surface pH of the product, thereby inhibiting the growth of bacteria; On the other hand, it removes oxygen and reduces the activities of lipoxygenase and polyphenol oxidase, so as to achieve the effect of fresh-keeping

in addition to the above-mentioned preservation methods, the preservation technologies such as controlled atmosphere, irradiation, chemistry, high pressure and supercooling are also being or are expected to be applied in shrimp preservation

2. Research progress in crab processing

crabs (including sea crab and Chinese mitten crab) have special physiological characteristics, such as multiple shelling, reproductive reflux, gonad and liver transformation, and have high requirements for natural reproduction conditions and living environment. Many countries and regions with hot and cold climates in the world do not have such products as computer products. China is located in the subtropical and temperate zone, and the temperature is appropriate, which is conducive to the growth and reproduction of crabs. It has become one of China's major aquatic resources, with large output and good quality. Not only domestic consumers like to eat, but also a large number of exports. Its edible value and economic value are very high

in addition to the original frozen crab, crab pieces, drunk crab, etc., crab processing can also be further processed to develop many nutritious food varieties that are easy to store, transport and eat, such as crab yellow powder, crab seeds, crab oil, crab yellow sauce, crab yellow soup, crab yellow monosodium glutamate, crab meat, crab meat quick-frozen food, canned crab meat and other condiments, food additives, flavor seasonings and other crab foods that adapt to the modern lifestyle. In addition, because crabs have health care and medical effects, and crab meat contains more protein, fat, carbohydrates, a variety of trace elements and vitamins, modern food processing technology can be used to extract its effective components and concentrate them to make hormone free drinks, granules, oral liquids, etc. for athletes

3. Medicinal processing of crustacean aquatic products

shrimp and crab are valuable aquatic products, which are famous for their delicious taste and tender meat. It is rich in protein, fat, sugar, calcium, phosphorus, iron, vitamin A, vitamin B1, vitamin B2, niacin, etc. Some crabs also contain a variety of free amino acids, lycopene, crab flavin and other nutrients. Sea shrimp is a good tonic for strength. Besides the above nutritional components, lobster also contains iodine, vitamin E and bile retention, which can tonify the kidney and Yang, nourish yin and strengthen the spleen; Crabs have the health functions of clearing away heat, dampness and fatigue

there are many studies on the medicinal use of crustacean aquatic products abroad. For example, molting inhibitory hormone (MIH) and hyperglycemic hormone with the function of regulating glucose level in blood lymphocytes were found in the six major pathogens belonging to chhs isolated from the sinus gland extract of Penaeus japonicus; Three cytochrome neuroabortive hormones were isolated from the aqueous extract of the sinus gland of Penaeus japonicus; N-acetylglucosidase was isolated and purified from hepatopancreas; It was found that the blood cells of shrimp and crab contained bactericidal peptides

in addition, a large number of studies have been carried out at home and abroad on chitin and its derivatives, a by-product of the processing of crustacean aquatic products. It is found that these substances have physiological effects such as preventing hypertension and hyperlipidemia, treating diabetes, regulating human immune function, etc; Astaxanthin has many physiological functions, such as inhibiting tumorigenesis, enhancing immunity, clearing free radicals in the body, etc. it has a good therapeutic effect on skin cancer caused by ultraviolet light, and also has a good preventive and therapeutic effect on eye disease caused by diabetes. It has a broad application prospect in health products, medicine, etc

4. Comprehensive utilization of shrimp and crab wastes

according to the determination, the protein content in shrimp head and shell is 20%~40%, crude fat is 9%, and it is rich in minerals, especially calcium and earth salt; It is also reported that shrimp and crab shells contain chitin (20% - 30%), protein (30% - 40%), calcium carbonate and calcium phosphate (30%~50%) and several pigments. Therefore, shrimp and crab wastes can be used to prepare protein flavoring elements, crab oil, shrimp naphtha, aromatics, astaxanthin and calcium to make calcium supplements

the comprehensive utilization of shrimp and crab is not only the extraction of nutrients, but also the development of shrimp and crab shell chemical products. Shrimp and crab shells are good raw materials for manufacturing chitin. Chitin is a kind of straight chain high molecular polysaccharide extracted from the shell of shrimp and crab. Its chemical structure and properties are similar to those of cellulose. Due to the existence of special amino groups in the molecules, it has many functions that cellulose does not have. It can remove inorganic salts and proteins through acid and alkali; Oxidation reduction to remove pigments and impurities; Many derivatives such as acylation and sulfonation can be obtained by different chemical modification reactions. Because chitin and its derivatives have special physical and chemical properties, they can be widely used in food, feed, medicine, tobacco, chemical industry, daily cosmetics, biochemical tests, food additives, sewage treatment and other fields

source: (Fenghua Agricultural Economics)

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