Why is the precipitated casein stirred with a mixture of ethyl alcohol and diethyl ether?

The precipitated casein is stirred with a mixture of ethyl alcohol and diethyl ether to remove any residual water and to help in the purification process. Ethyl alcohol helps to solubilize some impurities, while diethyl ether aids in the removal of lipids and other non-polar substances. This combination effectively helps in isolating pure casein, enhancing its stability and usability in various applications.