How can I keep potatoes from turning brown after they have been peeled and cut for cooking later in the day?
When I am having company for dinner and I’m serving mashed potatoes, I always peel the potatoes early in the day to save time. To keep them from turning brown, all you have to do is put them in cold water. The reason potatoes turn brown after they’re peeled is that they oxidize. The water keeps them from coming into contact with oxygen in the air. It’s similar to metal rusting, but in this case water prevents discoloring instead of causing it.
This works for many kinds of potato preparations. You can peel and cut potatoes for making fries, then place them in water. The trick here is to thoroughly dry the potatoes before frying to prevent the oil from spattering and burning you while they’re cooking. It’s best to dry them in a salad spinner and then blot with paper towels.
You can use this do-ahead method on sliced potatoes for a gratin recipe. It also works well for potatoes that are sliced but not peeled. Remember, unless the cooking method you’re using involves boiling, it’s important to dry potatoes before proceeding with your recipe.