The isolation of casein 1. 50 mL Reduced-fat milk. 100 ml beaker 40 oC Dilute acetic acid (1: 9)2 mL 2. Cool down for 10 min, 3000 r/min 15 min centrifugation 3. Separate the sediment, mixed with 95%o etoh 20 mL suction filtration 4. 10 mL EtOH: Et2O=1: I wash twice, 5 mL Et,O wash suction filtration 5. Dry and weig h 6. Solute 0.5 g product in 5 mL 0.4M NaOH, biuret test.The isolation of casein 1. 50 mL Reduced-fat milk, 100 mL beaker 40 oC Dilute acetic acid ( 1:9 ) 2 mL 2. Cool down for 10 min， 3000 r/min 15 min centrifugation 3. Separate the sediment, mixed with 95% EtOH 20 mL , suction filtration 4. 10 mL EtOH：Et2O = 1:1 wash twice， 5 mL Et2O wash suction filtration 5. Dry and weigh 6. Solute 0.5 g product in 5 mL 0.4 M NaOH, biuret test