How long is the protein isolate stable once it's mixed into a shake ie. milk or water? in other words, how fast does it deteriorate once its mixed? is temperature a factor? is the solvent a factor? (water, juice, milk, etc.?) reason for asking its that mixing my prot-shake at work is a PITA and always ends up full of clumps, nowhere as good as the ones i mix at home w/a blender, plus at home you can always add more goodies like peanut butter, strawberries, oatmeal, bannanas, etc.