How to Keep Peeled Potatoes From Turning Gray

Cold Water and Vitamin C Prevent Discoloring in Potatoes

Keeping Potatoes from Turning Gray
Keeping Potatoes from Turning Gray. © David Murray / Getty Images

When peeled potatoes turn gray, they have been exposed to air for a while. The quality isn't compromised, so they're still OK to eat, but the appearance is off-putting.

How to Keep Peeled and Grated Potatoes From Turning Gray

There are several ways to prevent peeled potatoes from turning brown. All of them work to do one or more of the following:

  • Cool the temperature of the potato.
  • Reduce pH in the potatoes.
  • Limit the amount of air reaching the potatoes.

Try these tricks to prevent potatoes from turning gray when you peel or grate them:

  • To keep peeled whole or cut potatoes white, cover them with cold water until you are ready to use them. Then, drain the potatoes and pat them dry before cooking them. (You don't need to drain and pat dry if the potatoes are headed into a pot of boiling water.) This trick even works overnight, as long as they are refrigerated.
  • When grating potatoes for recipes like potato pancakes, potato pie, and potato kugels, mix in a little ascorbic acid, which is nothing more than vitamin C powder. A pinch of crushed vitamin C tablet in a little water works just fine even after the potatoes have already turned gray. The acid magically whitens them again by changing the pH.
  • Combine both these methods by soaking the potatoes in a bowl of cold water mixed with vinegar or lemon juice.
  • Vacuum pack the peeled or grated potatoes to prevent air from causing the discolorization.

Why Potatoes Turn Gray

Potatoes, along with apples, pears, bananas, and peaches, contain an enzyme that, when exposed to oxygen, reacts to produce a discoloring on the surface of the potato or fruit. To prevent this reaction, the enzyme must be deactivated through one of the methods mentioned in this article.

Polish Gray Dumplings

Sometimes, gray potatoes are a good thing. In Poland, kluski czarne (black dumplings), also known as kluski żelazne (iron dumplings) or kluski szare (gray dumplings), are a variation on kluski śląskie.

In addition to mashed potatoes and flour, grated potatoes that are intentionally allowed to oxidize or turned dark, are added to the dough to give it a gray color. Although kluski were once considered peasant food, today they appear at gourmet restaurants in Europe as a side dish instead of potatoes.