Detection Method of Feed Additive Lysine

In recent years, feed additive lysine has been widely used in poultry feed, but counterfeit and inferior products continue to enter the market. Therefore, it is necessary to improve the quality awareness of buyers and combine various detection methods to prevent fake and inferior lysine from entering feed manufacturers and aquaculture. Here are some simple and fast methods for the detection of feed additive lysine that are easy to identify the authenticity.

Ⅰ. Physicochemical properties of lysine

True lysine extract is white or light brown small particles or powder. True lysine is odorless or slightly sour, while counterfeit lysine has a bad smell and some are aromatic.

Ⅱ. The main detection index and detection method of lysine

1. Sensory detection method

Pure lysine additive is small white or light brown granules or powder, tasteless or slightly peculiar smell, with a sour taste in the mouth, no astringent feeling in the mouth; fake lysine has a bad smell, with an impurity-like astringent feeling, and some have an aromatic smell.

2. Simple detection method

False and inferior lysine constantly appears in the market circulation, and there are various forms of counterfeiting, such as using starch, stone powder, gypsum powder, etc. to impersonate or mixing such substances into lysine. Therefore, it is necessary to quickly identify the true and false of lysine without an automatic amino acid analyzer.

3. Solubility test

Lysine supplements are easily soluble in water, but insoluble in ethanol and ether. Weigh 1g of lysine sample into a beaker, add about 50ml of distilled water, stir gently, the true lysine is completely dissolved, and the solution is clear without sediment. If the dissolution is not complete, the solution is cloudy or there are precipitated residues, it is fake or adulterated lysine. Put the beaker on the electric stove and heat it again. If the solution thickens into a paste, it means that the sample is fake and inferior lysine that is faked by starch or mixed with starch.

4. Burning method

Take about 1g of lysine sample into a porcelain crucible and burn it on an electric furnace. True lysine will emit an unpleasant smell similar to burning feathers when burning; while false lysine generally does not have this odor, or a lighter odor. After burning until there is no smoke, move it into a high-temperature furnace and burn at 550°C for about 2-3 hours. The burning residue of true lysine should be below 0.3%, and the residue is almost invisible to the naked eye. If there are many residues, it is fake and inferior methionine, and the adulterant can be further identified according to relevant methods.