Identification of aquatic products and their products (2)

31. Identification of contaminated fish rivers and lakes Due to the impact of industrial wastewater discharges, fish are contaminated and die, and these contaminated fish often enter the market for sale. The identification of contaminated fish has the following aspects: (1) Body shape: Contaminated fish often shows deformities, such as large heads and small tails, or large heads and small tails, and the abdomen grows and softens, the spine is bent, and the scales are yellowish. Redness or blueness. (2) Fish eyes: Contaminated fish. The eyeballs are cloudy and dull, and some of the eyes protrude outward. (3) Fish gills: Contaminated fish gills have a dull colour and usually have a whitening majority. (4) Odor; Contaminated fish, generally smells of ammonia, kerosene, hydrogen sulfide, etc., lack fishy smell. 32. What part of the puffer fish contains toxins? The poisons of puffer fish are mainly found in the ovary and liver. Secondly, in the kidneys, blood, eyes, fish gills, and skins, some puffer fish and meat also contain toxins. During the winter and spring, ovarian toxins are the most toxic. If people eat a piece of fish like a finger, they will be poisoned. 33, which parts of the carp contain toxins, also known as carp fish, mackerel and so on. The blood of this fish is black. After the cut of the fish's back, there is a blood line. The blood line is poisonous. If the fish is washed, the blood line will not be removed. Cooking and eating with the fish will cause the body to produce Allergy phenomenon, if the fish's abdomen is soft yellow, broken belly, paste mouth, etc., indicating that the fish has deteriorated and spoiled, if people eat this fish, will make the body swollen. 34. Which parts of the carp are home to the toxin carp, also known as the blue spot horse hinge, blue point carp, and other fish. Its quality is characterized by less spiny meat, garlic-shaped flesh, more tender. However, the liver of this fish contains toxic substances and cannot be eaten. Therefore, the fish liver must be removed when cleaning the fish. 35. Which parts of the pond fish have toxins? The fish is also known as blue round, stick fish, barb fish, pool fish and so on. This fish should be fresh and safe. If released for a long period of time, histidine in the fish will decompose rapidly and produce toxic ammonia. If people eat this fish, food poisoning will occur. 36, which part of the carp contains toxins carp, also known as carp, yubalang, beard fish and so on. It is a kind of freshwater wild fish, which is distributed in Heilongjiang River, Yellow River, Yangtze River and Pearl River Basin in China. It is a kind of fish with rich nutrition and tasty meat. However, when cleaning this fish, be sure to remove the eggs, because it is toxic and inedible. 37, which parts of the carp contain toxins, carp, also known as white peony, medlar, bitter chains and so on. It is a common freshwater fish, which is common throughout the year in the farmers' market in the Mainland. It is a popular and inexpensive fish. When people wash this fish, they need to remove the fish liver because it contains Poisonous to prevent food poisoning. 38. Which part of the carp is home to toxins and catfish is produced in Qinghai Lake. The viscera and eyes of this fish are poisonous. When cleaning fish, the internal organs and eyes must be removed to prevent food poisoning. 39. What part of the river cress contains toxins, also known as cockroaches, eels, and white cockroaches. The fish's serum contains toxins, wound fingers, do not come into contact with the river blood, in order to prevent wound inflammation, suppuration. 40. Why does Astragalus eat live jaundice, also known as squid, long fish and so on. In the private sector, there is a saying that "Summer Yellow Ginseng Race Ginseng" is said to be popular today. However, one thing to note is that squid can only eat fresh, slaughter is cooking, and should not eat dead stingray. Because the histidine contained in the body will quickly turn into toxic histamine after the death of the stingray, people will cause food poisoning after eating. The blood serum of Astragalus contains toxins. If there are wounds on the fingers of the people, once they come into contact with the blood of the fish, the wounds will become inflamed and purulent. 41. Why do dead turtles do not eat soft-shelled turtles, also known as group fish, commonly known as cockroaches or kings. Due to its tender meat, rich flavour and rich nutrition, the soft-shelled turtle is considered to be a tonic. However, dead turtles cannot eat. Since soft-shelled turtles contain more histidine, histidine is an important ingredient that has a special umami taste, and it can produce histamine after decomposition. Histamine is a strong straight tube expander, which can cause the release of a series of allergic substances. When the concentration is too high, it can cause symptoms such as prostration and shock. After the death of the soft-shelled turtle can be self-decomposition to produce ammonia, people eat dead turtles, it will cause food poisoning. 42. Freshness of aquatic products Sensory identification after boiled test For aquatic products with slightly less fresh or mildly odor-saturating products, when the sensory identification method is used to judge the freshness of the product, it is possible to pass the boiled test to smell odors. Taste, combined with the observation of soup to identify. When boiling test, the sample is generally not more than half a kilogram, and the amount of water discharge is appropriate to just immerse the sample. First, the water in the container is boiled, and then the sample of the deceased person and the lid of the container are heated. When the bottle is boiled again, the heat source is removed, and then the lid is opened for identification. (1) Odor Identification The scent of fresh products - with the inherent flavor of this species. The odor of deteriorating products - there is a stench or ammonia smell. (2) Taste: The taste of fresh products is differentiated from the natural taste of this product. The texture of the meat is elastic. The taste of the deteriorating product - no umami, fleshy hair, ammonia odor. (3) Soup Identification of soups for fresh products - soup sauce, with the color of this type of pigment, no meat in the soup. Deteriorated soup - turbid soup, fleshy spoilage suspended in the soup. 43. Rapid test method for the freshness of aquatic products (1) Determination of pH: The pH value is the same as the meat freshness test. Identification: fresh fish - pH 6.5 ~ 6.8. Fresh fish - The pH is 6.9-7.0. Metamorphic fish - the pH is above 7.1. (2) Hydrogen Sulfide Measurement Operation: Weigh 20 grams of sample fish into a small jar, add 40 ml of 10% sulfuric acid solution, and place a square or round filter paper larger than the bottle mouth in the middle of the filter paper block. Drop 1 to 2 drops of 10% lead acetate alkaline solution, and then place the drop with one side down on the bottle mouth and use a rubber band. After 15 minutes, remove the filter paper and observe the color change. Identification: Fresh fish - Lead acetate alkaline solution, no change in color, negative reaction (-). Fresh fish - Appears slightly brown or brown near the edge of the sputum, as a suspected reaction () or a weak positive reaction (+). Corrupt fish - all drip sites are brown, darker at the border, positive reaction (+ +), or dark brown, strong positive reaction (+++). (3) Determination of ammonia: Take a large piece of fish flesh, hung on a glass rod with a rubber stopper attached to the other end with a hook, and use a pipette to draw Aibeier test solution (take 25% of hydrochloric acid with a specific gravity of 1.12, no Aqueous ether 1 part, 96% alcohol 3 parts mixed Serve) 2ml, into the tube, after a little shaking, the glass rod with a rubber stopper into the test tube (note, do not touch the wall) until the sample From 1 to 2 cm above the liquid surface, quickly tighten the rubber plug and immediately observe it in a black background to see changes in the circumference of the sample in the test tube. Identification: Fresh fish - no white clouds appear, negative reaction (-). Secondary fish - there was a little white cloud at the instant that the sample was removed from the test tube, but it immediately dissipated. It was a weak positive reaction (+): or after the test sample was placed in a test tube, only after a few seconds there was a clear cloudiness. Positive reaction (++). Metamorphic fish - After the test sample was placed in a test tube, cloudiness immediately appeared, which was a strong positive reaction (+++). 44, identify the quality of kelp (1) good quality seaweed - the color is dark brown or brown green, leaves long and wide, thick and without root. There is a slight white powdered mannitol on the surface, with less sand and impurities. (2) Sub-quality seaweed - The color is yellow-green, and the leaves are narrow and thin. The general sand content is higher. 45, identify the quality of shark fins (1) good shark fins: shark's dorsal fin (ridge fins) and pectoral fins (wings). This type of shark fin is huge, with thick and dry fins, a clean surface with a slight sheen and no curling on the edges. Among them, there is a layer of fat-like meat in the ridge wing, and the fins are layered in the meat, which is rich in gelatin. Wings are thin, short fins, fresh texture. (2) Sub-quality shark fins: The shark's caudal fins (tail fins) are short and thin. 46. ​​Identification of bird's nest quality The bird's nest is a nest of swiftlets on the island. Dried products made by manual collection and cleansing, and shark fin and sea cucumber are listed as three kinds of expensive dishes. The quality of commodity bird's nests is divided into three levels. The first-class product is a red "blood bird's nest". The output is extremely small and extremely valuable. The second-class product is a white "white bird's nest" with a white color and a thick texture with less hair. Other products are "bird's nests" containing a large amount of feathers and impurities. The quality bird's nest is of good color, white in color, transparent in texture, thick in sac, and less in impurities. It can maintain the original ear shape. The color is yellow or gray, the capsule is thin and the quality of impurities is relatively poor, and the rise is small. The color is gray and the quality of the hair is the worst. 47. Identification of the quality of scallops The dried scallops are scallops, shells of Riyue Pui and Jiangbei, processed and dried dried seafood products. Each shellfish can only take a small piece of muscle, such as scallop processed by Jiangbei, with a slightly stripped shape, large, and high protein, sugar, and phosphorous content. The scallops are produced in the coastal areas of China, among which Shandong Rongcheng has the best quality. 48, to identify the quality of abalone dry abalone, also known as the general cap, ear shell. The shell is strong, hidden inside the shell, and the foot is quite developed. Abalone is flat and elliptical, with yellow and white color and no bones. The types of abalone in seafood include large abalone, variegated abalone and abalone. The abalone is dry and dry in texture. It is an oval-shaped ingot shape. There is a ring of flowers on the edge, the middle is convex, and the shape is complete. No impurities and taste are the top grades. The abalones sold in the market include three kinds of dried products: purple abalone, bright abalone, and gray abalone. The purple abalones are large in size and are purple, bright and of good quality. The abalone are large in size, the color is yellow, and the quality is good. Small individuals, dark gray color, quality times. 49, identify the quality of dried squid squid dry quality, generally body size, luster, color, thickness and other meat to grading. (1) First-grade products: pink flesh, bright and smooth, large body, thick flesh, complete body shape, dry texture, no mold, each body length is more than 20 cm. (2) Secondary products: pink flesh, bright and smooth, large body, thick flesh, complete body shape, dry texture, no mold, each body length in 14 to 19 cm. (3) Third grade products: pink flesh, slightly bright and smooth, small body, thin flesh, and relatively complete body shape, each body length is 8 to 13 cm. The size of the oilhead in China and the hanging piece in Kowloon are of excellent quality and the best sales. 50, to identify the quality of dry sea rice (1) color: the body surface is bright and shiny yellow or light red for the top grade, this shrimp are sunny drying, mostly pale. Dark and unclean, it is air-cured on rainy days, and it is generally salty. (2) Body shape: The shape of shrimp is curved, indicating that it is processed with live shrimp. The shrimps are straight or not very large in shape, and most of them are processed with dead shrimps. Body meat fat, no skin, no claws, no top shell for the top grade. (3) Impurities; shrimps are well-proportioned, with no impurities and other fish and shrimp as top grade. (4) Taste: Take a shrimp and chews it in the mouth. It is fresh and slightly sweet. Salt quality is of poor quality. 51. Identify the quality of mussels The mussels sold on the market are divided into four grades by size. (1) Small mussels: Also known as purple mussels. The smallest figure. As large as beans, the southern region is mostly soaked with boiling water, and can be eaten raw or seasoned before eating. (2) Mussel: Its size is the size of a jujube. (3) Large mussels: Their size is as big as jujube. (4) Extra large mussels: The largest body size is about 50 grams per 3 dry products. The quality characteristics of dried mussels are oblate, with middle seams, small hairs on the outside, and black and yellow color. When purchasing, it has a large body fat, brown color, shiny, uniform size, dry texture, fresh taste, no crushing and impurities for the top grade. 52, identification of the quality of fish maw Maw is the use of the snails of sea fish, processed by rinsing dried seafood products. The common fish maw on the market is yellow fish maw, scorpion belly belly, wide belly, Mao Chang belly and so on. The fish belly is generally straight and large, with a thick body, bright color, and a complete body shape. The body is small and thin, and the color is dark. The shape is not complete, and the color is black, indicating that it has deteriorated and cannot be eaten. 53. Identification of the quality of the fish skin Fish skin is a valuable dried seafood product processed using the skin of shark and yellow croaker. It is one of the most famous seafood dishes in China because of its high quality, high nutritional value and economic value. The method of distinguishing the quality of fish skins is mainly to observe the clarity, color and thickness of fish skin inside and outside the skin. (1) The inner surface of the fish skin: It is known as the side without sand, no residual meat, no residual blood, no dirt, no holes, transparent skin, thick cortex, white color, without salty taste for the top grade. If the color is dark and has a salty taste, it is a defective product, and it is not easy to rise when it is foamed. If the color is red, that is, it has deteriorated and decayed, it is called oil skin and cannot be eaten. (2) Fish skin surface: The surface of the fish skin is commonly known as sand-bearing. The color is grayish yellow, greenish black or pure black. It is rich in smooth skin, and the sand on the surface is easy to remove. This kind of skin has the best quality. If the surface of the skin is patchy, the sand is difficult to remove and the quality is poor. 54, to identify the quality of dried wolfberry stem is the use of fresh oyster meat through the seafood products made. There are the following three grades of wolfberry stems: (1) Large stem pods, made with larger pods, rectangular shape, tip fat, golden color, with the largest yield in Qidong County, Jiangsu Province. (2) Stem dry: The body length is about 25 mm, and the body is long-shouldered. There are two small apexes on the head (ie, the outlet pipe and the inlet pipe for drying the stems). Its quality is lower than that of Dabangan, and the yields in Fujian and Zhejiang are many. (3) Japan's dryness: Its quality is the same as that of a large, dry, round body, and its quality is not as good as that of our country. Good quality and dry, individual large and complete, meat hypertrophy, light yellow color, dry texture, smell clear, less salty, no broken, no sediment impurities. Poor quality pods dry, small individuals, incomplete shape, dark dull dark brown, mud stuck on the surface, salty smell, smell is not correct. 55, dry seafood products sometimes change the color of the phenomenon of dry seafood dry goods, is a common phenomenon, this is due to poor storage of dried products, or placed for too long, resulting in red color, flavor change, people call it Change. This is a deterioration that occurs most easily in storage of dry products containing salt and is caused by the proliferation of some salt-tolerant bacteria that produce iodine. To prevent variability, dry products should be stored in low-temperature or relatively dry warehouses. The packaging should be intact and kept out of contact with moist air. During the processing, attention should be paid to the cleaning of salt, barrels and other equipment to reduce the infection of salt-tolerant bacteria. If necessary, disinfect with a bleach solution. During storage and storage, it is necessary to intensify the inspection and early detection, and strive to quickly turn over the sun in the initial period of redness to reduce the water content of the fish, that is, to effectively prevent the redness of dried seafood products. 56. Causes of Dried Flavors in Dried Seafood Products Sometimes after dried products are stored for a long time, they often produce special hazel flavors. This is due to the oxidation of fat in the fish body in the air, resulting in a special bitter and astringent taste and slight odor, yellow or brown color, affecting the product appearance and food quality. The method to prevent dry products from appearing in the processing and storage is: For the varieties with more oil and fat, such as during dry processing in the summer, they should be temporarily placed in a cool place at noon to prevent fat oxidation caused by sun exposure, such as artificial drying. Also try to lower the temperature as much as possible to avoid subcutaneous fat oozing out of the surface and increasing the extent of the gallbladder. The dried products containing more fat that are supplied throughout the year should be stored in cool, ventilated, low-temperature and dry warehouses as much as possible, and more fatty pickled products should be stored with brine. 57. Method for mildew-proof during storage of dry seafood products Dried seafood products are prone to insect pests during storage and cause serious damage to the products when severe. Insect pests of dry products mainly include insects such as Insecticides and Decapods. In storage, first of all to prevent the breeding of insect pests in the warehouse, and often pay attention to maintaining the cleanliness of the warehouse. Sulfur or other appropriate insecticides should be used for fumigation and pest control before stocking in the warehouse. For products that have been pest-infested, they should be promptly sun-dried and beaten to allow the insects to be exposed and eliminated. Where there is a cold storage facility, pest-infested products should be stored in a cold store so that insect pests can be effectively prevented. 58. Principles of sensory identification and consumption of aquatic products and aquatic products As aquatic products contain high levels of protein and water, aquatic products are also rich in protein, and due to the high activity of enzymes in aquatic crystals, the body's pH is high and other reasons. As a result, they are easily contaminated by the growth and reproduction of microorganisms and thus rapidly spoil. Therefore, the quality of aquatic products and aquatic products, especially their freshness, is relatively high. The sensory identification has determined that the graded aquatic products and their products should be consumed or processed according to the following principles: (1) Fresh aquatic products or good quality aquatic products are not restricted and can be freely sold for consumption. However, the marketed astragalus, soft-shelled turtle, turtle, crab, blue crab, crab, small crab and various shellfish should be sold fresh. No one who has died can be sold or processed. (2) Sub-fresh or sub-quality aquatic products should often be sold immediately for consumption. It should be sold out at a strictly limited time, and must not be stored. If any further deterioration is discovered, it should be treated as corrupt food. (3) Metamorphic aquatic products and their products are prohibited from consumption or used as raw materials for food processing. According to the degree of corruption, it can be processed into feed, fertilizer or destroyed. 59. Identification of artificial sea bream and natural sea bream Artificial sea bream is made mainly of sodium alginate and gelatin, and then seasoned. The color is slightly yellow or milky white, brittle and lacks toughness, easy to break when pulled, and the mouthfeel is rough, such as chewing pink skin and slightly astringent. Natural jellyfish is a sea jellyfish root jellyfish, which is then marinated and marinated. The appearance of the jellyfish is milky white, yellowish-yellow and pale yellow, and the surface is moist and shiny. When pulled, it is not easily broken, and when it is bitten, it makes a sound. It has toughness and its shape is naturally round without breaking edges. 60, the identification of crab and artificial crab meat Crab meat is a more expensive food, and insufficient supply. Some people use cheap salmon meat to make artificial crab meat. Although the nutritional value hasn't changed much, the prices are much different. The fake crab meat is fake and it causes economic losses to consumers. Identification principle: Squid meat can show obvious colored stripes under focused beam irradiation. In addition, salmon, squid, squid, sea bream, and pike can also display colored patterns. Crab and shrimp do not produce this phenomenon. Procedure: Spread the sample thinly on the microscope slide, cover it with a similar slide, attach the ends with a rubber band, and place the slide in the light beam emitted by the B&L Nicollas. Samples, such as salmon or other fish processed or mixed with other fish, show colored stripes or patterns. However, crab meat that has not been mixed with fish has no such phenomenon. 61. Identification of cultured shrimp and shrimps for harvesting The current aquaculture industry has developed rapidly, especially shrimp farming has developed rapidly. There is little difference in nutrient composition and chemical composition between cultured shrimp and wild sea shrimp, but the taste of sea shrimp is better than that of cultivated shrimp, and the aftertaste is long. Therefore, the price of sea shrimp is much different when the shrimp are of the same size and the same freshness. Some traders make use of the lack of discriminating ability of consumers to breed shrimp that poses as sea shrimp. The appearance of the same species of shrimp is quite different. The culture of shrimp needs to be very long, and the shrimp must be short. Sharp and soft texture, while the head of shrimp caught in the ocean is short, blunt, and hard.

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