Mixing your Whey Isolate Protein drink. Fist question is there a difference with mixing it with water or milk? I work out during my lunch hour, so I can't have a gallon of milk at work, so would it be safe to mix it in the morning around 7:20 am with milk. Then take it work and put it in a frig till about 2:30 pm till I am done with my work out? Will the protein drink be good or would it lose some potent if I leave it in the frig that long?