I've been wondering if it might not actually be beneficial to mix protein with hot (or warm) water, at least post-workout. If you're looking to get protein digested as fast as possible (and you're not taking something pre-digested, like a hydrosylate), then you want the enzymes digesting the protein to work as fast as possible. Enzymes typically have a temperature range that they work best at. For enzymes in the human digestive tract, that temperature is almost certainly going to be body tempertaure (though I have no data to back this up). Therefore, drinking a cold protein drink is only going to slow down digestion. And not just because of of slower enzymes, the cold will also restrict blood flow in the stomach and possibly the small intestines, slowing everything down until your body heat warms it all up. A warm drink would not cause these problems, and could conceivably decrease the time it took to digest the protein and get the aminos into the muscles.
If we take this reasoning a little further, one could even predigest their protein drink by adding some enzymes (papain, bromelain, ?) to the drink and letting it sit for while. I wouldn't want to let a warm protein drink sit around too long, it might wind up becoming a Petri dish. But if you time it right, or throw it in the fridge after predigestion and then reheat it when you want to drink it, you might be able to make your own version of a rapidly absorbed hydrosylate.
Any thoughts?
Geoff