OK, let me rephrase that. My son is going on a scout trip tonight and they will be taking tin foil dinners --

You know, the kind that you can just throw in the campfire. I'm cutting the potatoes for him now. Is there anything I can do to the potatoes to keep them from turning black before he cooks them in about 3 hours? I can't keep them in a bowl of water, they need to go into the tinfoil now. Thanks.