Why Do Some Potatoes Turn Pink When You Cut Them?

At the first restaurant I ever worked in, I was in charge of making the hand-cut fries that we'd pile atop bowls of garlicky mussels. There is no better potato for French fries than russets, which, as you may know, are ultra-starchy and become gluey when you cut them. To help keep them from sticking to each other, the fries went straight from the cutting board to a bucket of water and then into the walk-in refrigerator to hang out until they were called up to the big leagues. It wasn't the most glamorous task, but everyone needs to start at the bottom, and in the food biz, the bottom almost always involves peeling potatoes.

During one shift on my first week on the job, the chef told me to bring him the bucket of fries I'd cut the night before. I ran down to the basement, stepped into the walk-in, and almost screamed in terror: before me was a five-pound bucket of thinly sliced potatoes, soaking in what appeared to be a sea of blood. I began checking to see if I had perhaps been profusely bleeding from some part of my body for two days. I began looking around to figure out if there was anything that could have contaminated it—did a fan blow the plastic wrap off the bucket, knock a few steaks into the water, and then blew the plastic wrap on again? I was having a pretty serious panic attack so I wasn't getting enough oxygen to my brain to make any sense or make any rational decisions. I grabbed a clean bucket, plunged my arms into the potato blood, and began scooping the fries out as fast as I could. When I returned to the kitchen a few minutes later, everything I was wearing from the waist down was dripping wet, but in my arms was a bucket full of clean potatoes. No one asked any questions.

Later, I learned that I had wet my pants for nothing. Potato cells contain these compounds called phenols, which are surrounded by enzymes, which are all bundled up nice and safely inside the rigid cell walls. When those cell walls are destroyed and get exposed to oxygen, they begin to turn pink. The more the potato is cut, the more reactions begin to happen—if you've ever grated them for latkes or casseroles, you've likely witnessed this phenomenon. The best way to prevent potatoes from turning pink is by submerging them in water, which keeps them from being exposed to oxygen. This works well if you're preparing a small amount of potatoes at home, or if you don't rush when putting many, many pounds of thinly cut fries into a water-filled bucket. When you do rush, you end up trapping pockets of air in the bucket, and as the potatoes begin to react with the oxygen, they slowly begin to turn the water blood red.

If your cut potatoes are white, or pink, or even a little purple, Dr. Potato of The Idaho Potato Commission says they're completely safe to eat and recommends adding a bit of vinegar to the soaking water to prevent discoloration. (Green potatoes are still a no-go.) Once the potatoes are cooked, they'll look normal. Most importantly, they won't taste like potato blood.