With the development of aquaculture, the demand for fishmeal is increasing. Some unscrupulous traders took advantage of the opportunity to make fake and profiteering. Domestic and imported fake fishmeal on the market are not uncommon. The bait prepared with adulterated fish meal not only affects the growth of the fish due to the nutritional imbalance of the bait, but also causes the fish to decline in physical fitness. This series of adverse effects not only causes significant economic losses to the user. It also destroys the reputation of domestic fishmeal. This paper introduces the method of identifying true and false fishmeal from two aspects: sensory recognition and simple chemical test.
1.Dissection mirror and microscopy
The sample is generally magnified 20-30 times under a dissecting microscope to be resolved, and if necessary, it can be further enlarged by a microscope. Fishmeal is a light substance such as yellowish brown or yellowish brown, which can be identified by the characteristics of fish, fish bones and scales.
The fish mirror has a rough surface and a fibrous structure, similar to meat powder, but with a light color. The fish bones are translucent to opaque silver, and some fish bones are amber and irregular. Fish scales are flat or curved transparent objects, with the same circle, alternating color depth, cracked surface of the scales, and cracked milky white.
Eg: Fish meal mixed with shrimp or shrimp powder
Shrimp powder, shrimp eyeballs, shrimp shells and shrimps can be seen in the fishmeal mixed with shrimp head powder. The shrimp shell resembles a curled mica-like sheet, which is translucent. A small amount of shrimp is tied to the shrimp shell. The shrimp eye is black spherical granules and is a more recognizable feature in shrimp head powder. Shrimp must be in the form of fragments under the microscope, oblong tubular with spiral parallel lines. The shrimp legs are broadly tubular, translucent, with or without hair.
Eg: Inspection of sand in fish meal
Take 10 grams of fishmeal sample, place it in a 100 ml beaker, add 5 times water, stir well and let it stand for 10-15 minutes. Fishmeal and sand sink to the bottom of the water, then gently stir, the fishmeal floats and rotates with the water. Rotating, while the sand is more important, it will sink to the bottom with a slight rotation, and the presence of sand can be observed at this moment.
Finally, it is necessary to remind a situation that is easily overlooked and made false. First, the water exceeds the standard, the weight is insufficient; second, there is no certificate, no specification, shelf life; third, the package is damaged, the label is incomplete (such as: product name, net weight, factory name, site, trademark, etc.). Although these conditions are not as serious as intentional adulteration, fraud, and counterfeiting, they are also enough to cause user losses. Because of this situation, it should be taken seriously.