Is it better to make protein shakes as you need them, or could I just make a big pitcher? I do not know whether or not the pitcher of protein shake would go bad if I do not go through it quickly enough.
It will taste like total shit and have a disgusting consistency long before it "goes bad" i would imagine.
Why on earth would you want to do that?
I mix a shake up each night to have first thing in the morning. I like the consistency better compared to shaking and drinking right away.
Make sure to refrigerate it though. And it will have some stuff settle out that needs re-suspended, so a big pitcher of it might not be the way to go.
If you blend fruit into your shake it will taste pretty bad after only a couple of hours. Some kind of reaction occurs between the protein and fruit.
Depends on what you put in your shakes. Mixing them right before drinking is best, but if you absolutely must make them ahead of time (to drink on a construction jobsite for example) I think a common-sense rule of thumb would be 'drink the same day' at the longest.
A ton of free amino acids floating around in water will put most microorganisms into hyperdrive. Just mix them as you need them.