The less time they sit, the better. Try to keep it to an hour or two. Here is the word from Julia:
"If you cannot serve at once, beat in only a minimum amount of milk, etc. (Turn the potatoes into a saucepan if you have used an electric mixer.) Set in another pan of hot but not simmering water, and cover the potatoes loosely--them must stay warm to retain their fresh quality, and they must have air circulation or they develop an off-taste. At serving time, bring the water to the simmer, beating the potatoes with a wooden spoon; then beat in more hot milk or cream and soft butter to your taste."
Julia's pretty strict--I would just leave the unmashed potatoes in their cooking water, reheat and let someone else drain and mash them at serving time. People are usually happy to help.
A complete idiot wouldn't care how her potatoes taste. smileys/smile.gif
Speaking of idiots, that off-taste applies to two other things: roast poultry and green beans. So why does every market in town offer roast turkey, mashed potatoes and green beans for reheating?
