Preparation method of coated isoacid

The invention provides a preparation method of coated isoacid. The method comprises the steps of: S1. mixing isoacid monomers 2-methylbutyric acid, isobutyric acid, isovaleric acid and valeric acid evenly according to a proportion of 20-25:30-37.5:12.5-15:25-30 to obtain isoacid, then adding white carbon black to conduct mixed adsorption for 20-30min to obtain a mixture A; S2. mixing the mixture A obtained in S1 with potato starch and sodium lignosulfonate in a ratio of 88-92:6-8:2-4 to prepare isoacid pellets; S3. preparing a 1-3% acrylic resin IV solution; S4. preparing a 1-3% sodium ethyl cellulose solution; and S5. coating the isoacid pellets by means of fluidized bed bottom spraying. By performing coating treatment on isoacid, the method provided by the invention covers up the odor of isoacid, and is beneficial to application of isoacid in animal feed adding. The method has the advantages of simplicity, high yield, low production cost, and large scale industrial production, and the prepared product is mo