Food Science: Why Do Peeled Potatoes Turn Pink?

Looking up from prep work to find your peeled and cut potatoes have all taken on a disconcerting pinkish hue is a bit startling and downright unappetizing! Why does this happen? Is it safe? And is there any truth in your mother's advice to hold cut potatoes in cold water? Take a look...Believe it or not, that lumpy, brown potato you're holding is actually a complicated package of chemicals and enzymes. Inside the potato are little pockets of things called phenols, which are essentially an acidic chemical compound. These phenols are surrounded by enzymes (proteins), and everything is held together inside the potato cell.

When you cut into the potato, you damage the cell walls that keep everything nice and tidy. The phenols and the enzymes meet the oxygen coming in from the outside world, causing a chemical reaction to take place. This chemical reaction results in - you guessed it - pink potatoes.

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.

Nothing can completely prevent this chemical reaction from taking place, but we've found a few things work to slow it down:

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. We would guess that the sharp knife does less damage to the cell walls, thus causing a lesser chemical reaction.

Use the potatoes right away. Prepping the potatoes is the last thing we do, and we try to time it so that they go straight from cutting board to pan. Less time hanging out letting phenols and enzymes mingle equals less pink in your final dish.

Submerge potatoes in cold water if they will stand longer than a few minutes. Yes, your mama had it right. Cold water cuts down contact between the potato cells and oxygen, creating a temporary seal over the cut surface. It doesn't actually prevent the reaction from taking place, but it definitely slows it down.

We've also noticed that grated potatoes go pink significantly faster than large chunks. The size of the cut potato isn't exactly something you can control since it depends on the recipe, but it's something to keep in mind when planning out your prep work.

Any one else have a sure-fire method for preventing potatoes from going pink?

Related: Tip: The Best Way to Store Potatoes

(Image: Flickr member smohundro licensed under Creative Commons)

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