1. Hydrolysis: accurately weigh 100g casein added to 1000ml three-necked bottle, and then sequentially add 100ml of distilled water stirring, 100ml 12mol / L of concentrated hydrochloric acid stirring, installed on the condenser tube, electric stirring, electric jacket, while stirring the temperature, when the temperature reaches 90 C when the solution as a whole boiled, constant temperature stirring hydrolysis of 3hr, to be hydrolyzed to solution hydrolysis thoroughly without casein particles to stop hydrolysis. The hydrolysis was stopped after the solution was completely free of casein particles.
2. Filtration: Add 100ml of distilled water to the hydrolyzed solution in step 1, and filter with 80 mesh nylon mesh.
3. Concentration: Add the above filtrate into 1000ml round bottom flask in several times, and concentrate it to paste form with rotary evaporator by depressurizing it to 650mmHg, add 100ml distilled water through negative pressure, and reduce the speed of rotary evaporator to make it dissolve completely. Then again decompression concentration to paste, so repeatedly concentrated washing three times, can complete the washing, at this time the pH value of 3.5.
4. Decolorization: add the above washed hydrolysis solution to the activated carbon with 5% mass fraction of solid content and reflux for 4.0 hours, then filter with filter flask, Brinell's funnel under hot decompression at 650mmHg, and the filtrate will be light yellow and the pH value will be 2.0.
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5. Deacidification: the light yellow filtrate after decolorization is exchanged by strong alkaline anionic 201×7(717) resin in one step, and the exchange liquid component of pH 6.5-7.0 section is collected.
6. Drying: After the resin exchange solution is concentrated, spray-dried at a pressure of 15MPa and a temperature of 120, the product is milky white or light yellow.
