The Reason

• When raw potatoes are peeled and sliced, phenols and enzymes are exposed to air, causing oxidation, or browning. Sometimes, the potato slices may even appear pink. This oxidation process is exactly the same chemical reaction that causes sliced apples, peaches and bananas to turn brown. Browned potatoes are perfectly safe to eat, and the discoloration usually disappears during cooking. Storing sliced potatoes in cold water helps minimize their contact with oxygen so they stay white longer. Add a teaspoon of citric acid, sold at natural food stores or in the canning section of grocery stores, to further slow the oxidation process.

The Short Answer

• Whenever possible, store sliced potatoes in water for no more than two hours. As the potatoes sit in water, nutrients leach out of them. Use the coldest water possible, and rinse and drain the potatoes thoroughly before you cook them. Pat the potatoes dry if you're baking or frying them. To boil the potatoes, simply place them in a pot and cover them with water.

Long-Term Goals

• In a perfect world, those sliced potatoes will spend minimal time in cold water. However, sometimes it's necessary to cut potatoes ahead of time -- especially for a large group or a holiday meal. You can safely store the potatoes in cold water overnight in a covered container in the refrigerator. This longer storage will diminish the nutrient value of the potatoes slightly, but sometimes convenience trumps other considerations.

Tips for Success

• Although there's no surefire way to prevent sliced potatoes from browning, using a sharp knife seems to help slow the process, according to the Kitchn website. Also, thinly sliced or grated potatoes brown more quickly than potatoes cut into chunks, because more surface areas of the potatoes are exposed to air. Store peeled whole potatoes, rather than thinly sliced or grated potatoes, overnight. The next day, drain them well and slice or grate them immediately before using them.