This discoloration isn't harmful to us and you can still eat those potatoes - it can just be a bit off-putting to serve a plate of pink potatoes! FYI: This is actually the exact same chemical reaction that makes apples, bananas, and other fruits turn brown and mushy. â¢ Use a sharp knife. We weren't able to find any scientific basis for this, but we've definitely noticed a difference between chopping potatoes with a dull knife verses a sharp one.