Identification of true and false methionine and lysine in chicken feed
The application of methionine and lysine in the breeding industry is increasingly widespread, and the price is high and the social needs are large. On the other hand, incidents of counterfeit amino acid pits in the market have occurred from time to time, so it is necessary to understand the method of mastering anti-counterfeiting.
The application of methionine and lysine in the breeding industry is increasingly widespread, and the price is high and the social needs are large. On the other hand, incidents of counterfeit amino acid pits in the market have occurred from time to time, so it is necessary to understand the method of mastering anti-counterfeiting. The identification test of true and false methionine and lysine is introduced as follows:
First, sensory identification
(1) Visual methionine is white or light yellow crystalline powder or flake, which is reflective; lysine is white or light brown small particles or powder.
(2) Olfactory methionine has a special odor, lysine is odorless or slightly heterosexual, and the scent of pseudo-lysine is not correct, and some have aromatic sputum.
(3) The tactile methionine handkerchief is smooth and creamy.
(4) The taste methionine is slightly sweet in the mouth, and the lysine has a sour taste. Counterfeit amino acids generally have a bad taste and have an impurity-like feel.
(5) Dissolve a small amount of sample and add it to 100 ml of water, stir for 5 minutes, then let it stand. It can completely dissolve the precipitate without any product. If there is sediment residue or floating matter, it is adulterated or counterfeit.
Second, chemical inspection
(1) The content of burning methionine and lysine is higher than 98.5%, and it can be burned out quickly after burning, and there is basically no residue. If the combustion is incomplete, there is obvious burning residue, which is adulteration or counterfeiting. Pure methionine and lysine ignite an unpleasant special odor, similar to burning feathers, and counterfeit amino acids generally do not have this odor.
(2) Reagent reaction 25 mg of methionine, add 1 ml of anhydrous sulfuric acid copper saturated sulfuric acid solution, present yellow in the test tube; 1 g of lysine, dissolve in 100 ml, take 5 ml of this solution and add 1 ml of benzotrione The solution was heated for 3 minutes, then 20 ml of water was added and allowed to stand for 15 minutes to give a reddish purple color.
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