With the development of aquaculture, the demand for fishmeal is increasing. Some unscrupulous traders took advantage of the opportunity to make false profits and seek profits. Domestic and imported counterfeit fishmeal are on the market today. According to the introduction of the city's feed inspection department, fishmeal is mixed with crab shell powder, shrimp shell powder, blood powder, feather powder, leather powder, cottonseed meal, rapeseed meal, chaff, and urea. The amount of adulterated food is carefully calculated; therefore, the protein content of adulterated fish meal determined by the Kjeldahl method can reach the level of national standard (GB) grade 1 and 2 fishmeal, but the quality and quantity of true protein are very high. low. Amino acid composition is not balanced. With bait mixed with adulterated fishmeal, the Nutritional imbalance of the bait not only affects the growth of the fish, but also results in a decrease in the fish's constitution, reduced resistance to disease, an increase in the feed coefficient, an increase in urine excretion, and a serious water pollution. This series of adverse effects can not only cause major economic losses to users. But also destroyed the reputation of domestic fishmeal. Therefore, we must consciously persist in cracking down on the one hand, and on the other hand, we must improve our ability to identify true and false fish meal. This article describes the method of identifying true and fake fishmeal from the aspects of sensory recognition and simple chemical testing.
one. Sensory impression
1. Visual: High-quality fishmeal is generally uniform in color, red-brown, yellow-brown or yellow-brown. Evenness of fineness. Poor fishmeal is light yellow, white or dark brown. Fineness and uniformity are poor. Adulterated fish meal is yellow-white or red-yellow, with poor fineness and evenness. Mixed with weathered earth fish, pink color is yellowish. If the fish meal is damp, the protein is denatured except for agglomerates, and the general color is white or gray, and the flavor is rich and dull. If the color is darker, the burning smell may be self-burning fish meal.
2. Olfactory: High-quality fishmeal has a salty smell; poor-quality fishmeal has a stench, rancid or hazel taste; adulterated fishmeal has a pale smell, oily taste, or ammonia taste. If the number of adulterants is still relatively easy to distinguish. The fishmeal mixed with cottonseed meal and rapeseed meal has the taste of cottonseed meal and rapeseed meal, fish meal mixed with urea and slightly ammonia smell.
3. Tactile: High-quality fishmeal Handkerchiefs are soft and fishy and no sand; low-quality fish meal and adulterated fish meal are due to less muscle fiber content, and they are harder and rougher.
two. Dissecting microscope and microscopy examination under the microscope can generally enlarge the sample 20-30 times to distinguish, if necessary, can be used to further enlarge the microscope. Fishmeal is light brown, yellowish brown, etc., and can be identified according to the characteristics of fish, fish bones, and scales.
Fish mirror surface roughness, with a fibrous structure, similar to meat powder, but the color is light. Fish bones are translucent to opaque silver, some fish bones are amber and irregular. Fish scales are flat or curved transparent objects, with the same circle, alternating colors and shades, cracked surface of fish scales, cracks milky white.
Mirror inspection of adulterated fish meal:
1. Seed meal with rapeseed meal mixed with rapeseed meal can be seen under the microscope seed coat seed coat, its testa characteristics are brown and thin, the outer surface of a honeycomb mesh, the surface is shiny, the inner surface of a soft translucent White flakes adhere. The seed coat of the rapeseed meal and the seed kernel pieces are not linked together, and the kernels are light yellow, irregular in shape and dull.
2. The fish meal mixed with cotton kernel cake was mixed with cotton seed cake. The cotton fiber was attached to the shell and the cake granules under the microscope. The cotton fiber was a white thread, hollow, flat, curled, translucent, and shiny. Cottonseed husks are brown or reddish brown and thick. Along its edge, there are different shades of light yellow or tan, with a stair-like surface. Cottonseed kernels are yellow or brownish and contain many round flat black or reddish brown oil glands or gossypol glands.
3. The rice husk pieces were found in the rice flour powder mixed with rice hull flour and mixed with rice hull powder. The surface of the husk flour had shiny and well-shaped stripes, and the surface of the shell was found to be hairy.
4. Peanut meal mixed with peanut meal fish meal mixed peanut cake can be seen under the microscope peanut shell and seed coat, shell broken, irregular, different thickness of the sheet, layered. The inner layer is white spongy, with fibers intertwined, with ribs on the surface of the outer layer. The seed coat is red, pink, dark purple or brown-yellow.
5. The sesame seed cake was mixed with sesame seed meal in the fishmeal fishmeal. The sesame seeds were thin, and the surface was covered with tiny round protrusions, black, brown or tan, depending on the variety.
6. Fish meal mixed with soy Bean flour was mixed with soy bean powder and the skin was found to be yellow, or light yellow. The bean skin has concave spots, a slight curl, and a visible umbilical cord. Under the microscope, the white sponge-like starch floats on the surface of the block.
7. Wheat bran mixed with fish meal mixed with wheat bran microscope can be seen light yellow or brown, flaky bran. The outer surface of the bran has fine wrinkles and the inner surface has many opaque white starches.
8. Blended leather powdered fishmeal fishmeal can be seen in Green , dark green and brick-red lumps or filaments in leather powder mirrors. Like sawdust, it is not as transparent as hydrolyzed feather powder.
9. Mixed with hydrolyzed feather meal fishmeal fish meal mixed with hydrolyzed feather powder mirror visible translucent irregular broken particles, some reflective. At the same time, the feather shaft can be seen as a hollow circle. Raw feathers that have not been fully hydrolyzed can also be seen.
10. Fishmeal mixed with shrimp head or shrimp meal is mixed with shrimp head shrimp powder, shrimp eyeball, shrimp shell and shrimp meat. Shrimp shell resembles curled mica-like flakes, translucent. A small amount of shrimp meat and shrimp shell together. Shrimp eyes are black spherical granules, which are easily identifiable in shrimp head powder. Shrimp should be in the form of broken pieces under the microscope, oblong tube with spiral parallel lines. Shrimp legs are wide tubular in section, translucent, with or without hairs.
11. The crab shell characteristics were observed in the crabmeal powder mixed with crab shellfish meal. Crab shells are regularly fragmented, and the shells are mostly orange-red, porous, and have a honeycomb-like circular dimple.
12. The powdered fishmeal mixed with fishmeal of shellfish mixed with shell powder can be seen under the microscope. The tiny particles of the shells are smooth and the color varies depending on the type of shell. Some are white or gray, and some are pink. Some particles have concentric or parallel textures on the outer surface or dimly interlaced strands, some of which are jagged.
13. Fish powder mixed with kelp powder in fish meal was mixed with lamellar granules with light yellow spots and light yellow spots under the kelp powder microscope. The size and shape were very irregular.
14. Blood meal mixed with fish meal in the fish meal can be seen under the blood powder characteristics of blood powder, blood powder particles in the mirror under different shapes, some sharp edges, and some rough edges are not neat. The color is black like asphalt, some blood red shiny beads.
15. The fishmeal mixed fishmeal powder mixed with meat and bone meal can be seen in yellow to dark brown granules under the microscope. It has a dark color with a high fat content, and has a shiny oil-reflecting luster, and its surface is rough. Microscopic, interconnected muscle fibers can be seen under the microscope. The bone is white, gray or light brown-yellow blocky particles, opaque or translucent, with spots, and the edges are pure. In addition, hair, hooves, and the like can also be seen, and the characteristic of mixing blood powder can often be seen.
three. Physical inspection
1. The urea-incorporated test of fishmeal contains imported urea and imported fishmeal to increase the protein content of the test results and to impersonate high-grade fishmeal. Identification method can be used burning test: 20 grams of fishmeal on a clean piece of iron, heated to 70 °C with an electric furnace, such as emitting a pungent smell of ammonia is likely to incorporate urea.
2. Fish meal mixed with bran, peanut shell flour, rice hull flour test 10 grams of fish meal sample, placed in a 100 ml glass beaker, adding 5 times water, fully stirred, let stand 10-15 minutes, bran, peanuts Shell flour and rice hull flour are light in weight and float on the water.
3. The fish meal was mixed with sand and 10 grams of fish meal samples were taken and placed in a 100 ml beaker. Water was added 5 times. Stir thoroughly and let stand 10-15 minutes. Fishmeal and sand were all submerged into the bottom of the fish and gently stirred. Fishmeal As it floats, it rotates with the flow of water, and the sand has a large proportion. It rotates and sinks into the bottom of the water. At this moment, the presence of sand can be observed.
4. Test of fish meal mixed with feather meal 10 g of fish meal sample was placed in a mixture of carbon tetrachloride and petroleum ether (the ratio of carbon tetrachloride to petroleum ether was 100:41.5), stirred and stood still. Feather was mostly feathered. powder.
5. Using a method of measuring the weight of the fish to measure pure fishmeal with a particle size of 1.5mm, the bulk density is about 550g to 600g per litre. If the bulk density is too large or too small, it is not pure fishmeal.
The above describes the simple identification method for true and false fish meal. Finally, we need to remind a situation that it is easy to overlook the phenomenon of doping. First, excessive moisture, lack of weight; Second, no certificate, no instructions, shelf life; Third, packaging damage, incomplete indications (such as: name, net weight, plant name, site, trademarks, etc.). Although these circumstances are not as serious as intentional adulteration, fraud, or counterfeiting, they are also sufficient to cause user losses. Due to the widespread existence of this situation, attention should also be paid.
one. Sensory impression
1. Visual: High-quality fishmeal is generally uniform in color, red-brown, yellow-brown or yellow-brown. Evenness of fineness. Poor fishmeal is light yellow, white or dark brown. Fineness and uniformity are poor. Adulterated fish meal is yellow-white or red-yellow, with poor fineness and evenness. Mixed with weathered earth fish, pink color is yellowish. If the fish meal is damp, the protein is denatured except for agglomerates, and the general color is white or gray, and the flavor is rich and dull. If the color is darker, the burning smell may be self-burning fish meal.
2. Olfactory: High-quality fishmeal has a salty smell; poor-quality fishmeal has a stench, rancid or hazel taste; adulterated fishmeal has a pale smell, oily taste, or ammonia taste. If the number of adulterants is still relatively easy to distinguish. The fishmeal mixed with cottonseed meal and rapeseed meal has the taste of cottonseed meal and rapeseed meal, fish meal mixed with urea and slightly ammonia smell.
3. Tactile: High-quality fishmeal Handkerchiefs are soft and fishy and no sand; low-quality fish meal and adulterated fish meal are due to less muscle fiber content, and they are harder and rougher.
two. Dissecting microscope and microscopy examination under the microscope can generally enlarge the sample 20-30 times to distinguish, if necessary, can be used to further enlarge the microscope. Fishmeal is light brown, yellowish brown, etc., and can be identified according to the characteristics of fish, fish bones, and scales.
Fish mirror surface roughness, with a fibrous structure, similar to meat powder, but the color is light. Fish bones are translucent to opaque silver, some fish bones are amber and irregular. Fish scales are flat or curved transparent objects, with the same circle, alternating colors and shades, cracked surface of fish scales, cracks milky white.
Mirror inspection of adulterated fish meal:
1. Seed meal with rapeseed meal mixed with rapeseed meal can be seen under the microscope seed coat seed coat, its testa characteristics are brown and thin, the outer surface of a honeycomb mesh, the surface is shiny, the inner surface of a soft translucent White flakes adhere. The seed coat of the rapeseed meal and the seed kernel pieces are not linked together, and the kernels are light yellow, irregular in shape and dull.
2. The fish meal mixed with cotton kernel cake was mixed with cotton seed cake. The cotton fiber was attached to the shell and the cake granules under the microscope. The cotton fiber was a white thread, hollow, flat, curled, translucent, and shiny. Cottonseed husks are brown or reddish brown and thick. Along its edge, there are different shades of light yellow or tan, with a stair-like surface. Cottonseed kernels are yellow or brownish and contain many round flat black or reddish brown oil glands or gossypol glands.
3. The rice husk pieces were found in the rice flour powder mixed with rice hull flour and mixed with rice hull powder. The surface of the husk flour had shiny and well-shaped stripes, and the surface of the shell was found to be hairy.
4. Peanut meal mixed with peanut meal fish meal mixed peanut cake can be seen under the microscope peanut shell and seed coat, shell broken, irregular, different thickness of the sheet, layered. The inner layer is white spongy, with fibers intertwined, with ribs on the surface of the outer layer. The seed coat is red, pink, dark purple or brown-yellow.
5. The sesame seed cake was mixed with sesame seed meal in the fishmeal fishmeal. The sesame seeds were thin, and the surface was covered with tiny round protrusions, black, brown or tan, depending on the variety.
6. Fish meal mixed with soy Bean flour was mixed with soy bean powder and the skin was found to be yellow, or light yellow. The bean skin has concave spots, a slight curl, and a visible umbilical cord. Under the microscope, the white sponge-like starch floats on the surface of the block.
7. Wheat bran mixed with fish meal mixed with wheat bran microscope can be seen light yellow or brown, flaky bran. The outer surface of the bran has fine wrinkles and the inner surface has many opaque white starches.
8. Blended leather powdered fishmeal fishmeal can be seen in Green , dark green and brick-red lumps or filaments in leather powder mirrors. Like sawdust, it is not as transparent as hydrolyzed feather powder.
9. Mixed with hydrolyzed feather meal fishmeal fish meal mixed with hydrolyzed feather powder mirror visible translucent irregular broken particles, some reflective. At the same time, the feather shaft can be seen as a hollow circle. Raw feathers that have not been fully hydrolyzed can also be seen.
10. Fishmeal mixed with shrimp head or shrimp meal is mixed with shrimp head shrimp powder, shrimp eyeball, shrimp shell and shrimp meat. Shrimp shell resembles curled mica-like flakes, translucent. A small amount of shrimp meat and shrimp shell together. Shrimp eyes are black spherical granules, which are easily identifiable in shrimp head powder. Shrimp should be in the form of broken pieces under the microscope, oblong tube with spiral parallel lines. Shrimp legs are wide tubular in section, translucent, with or without hairs.
11. The crab shell characteristics were observed in the crabmeal powder mixed with crab shellfish meal. Crab shells are regularly fragmented, and the shells are mostly orange-red, porous, and have a honeycomb-like circular dimple.
12. The powdered fishmeal mixed with fishmeal of shellfish mixed with shell powder can be seen under the microscope. The tiny particles of the shells are smooth and the color varies depending on the type of shell. Some are white or gray, and some are pink. Some particles have concentric or parallel textures on the outer surface or dimly interlaced strands, some of which are jagged.
13. Fish powder mixed with kelp powder in fish meal was mixed with lamellar granules with light yellow spots and light yellow spots under the kelp powder microscope. The size and shape were very irregular.
14. Blood meal mixed with fish meal in the fish meal can be seen under the blood powder characteristics of blood powder, blood powder particles in the mirror under different shapes, some sharp edges, and some rough edges are not neat. The color is black like asphalt, some blood red shiny beads.
15. The fishmeal mixed fishmeal powder mixed with meat and bone meal can be seen in yellow to dark brown granules under the microscope. It has a dark color with a high fat content, and has a shiny oil-reflecting luster, and its surface is rough. Microscopic, interconnected muscle fibers can be seen under the microscope. The bone is white, gray or light brown-yellow blocky particles, opaque or translucent, with spots, and the edges are pure. In addition, hair, hooves, and the like can also be seen, and the characteristic of mixing blood powder can often be seen.
three. Physical inspection
1. The urea-incorporated test of fishmeal contains imported urea and imported fishmeal to increase the protein content of the test results and to impersonate high-grade fishmeal. Identification method can be used burning test: 20 grams of fishmeal on a clean piece of iron, heated to 70 °C with an electric furnace, such as emitting a pungent smell of ammonia is likely to incorporate urea.
2. Fish meal mixed with bran, peanut shell flour, rice hull flour test 10 grams of fish meal sample, placed in a 100 ml glass beaker, adding 5 times water, fully stirred, let stand 10-15 minutes, bran, peanuts Shell flour and rice hull flour are light in weight and float on the water.
3. The fish meal was mixed with sand and 10 grams of fish meal samples were taken and placed in a 100 ml beaker. Water was added 5 times. Stir thoroughly and let stand 10-15 minutes. Fishmeal and sand were all submerged into the bottom of the fish and gently stirred. Fishmeal As it floats, it rotates with the flow of water, and the sand has a large proportion. It rotates and sinks into the bottom of the water. At this moment, the presence of sand can be observed.
4. Test of fish meal mixed with feather meal 10 g of fish meal sample was placed in a mixture of carbon tetrachloride and petroleum ether (the ratio of carbon tetrachloride to petroleum ether was 100:41.5), stirred and stood still. Feather was mostly feathered. powder.
5. Using a method of measuring the weight of the fish to measure pure fishmeal with a particle size of 1.5mm, the bulk density is about 550g to 600g per litre. If the bulk density is too large or too small, it is not pure fishmeal.
The above describes the simple identification method for true and false fish meal. Finally, we need to remind a situation that it is easy to overlook the phenomenon of doping. First, excessive moisture, lack of weight; Second, no certificate, no instructions, shelf life; Third, packaging damage, incomplete indications (such as: name, net weight, plant name, site, trademarks, etc.). Although these circumstances are not as serious as intentional adulteration, fraud, or counterfeiting, they are also sufficient to cause user losses. Due to the widespread existence of this situation, attention should also be paid.
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