You grabbed a couple of potatoes in your weekly grocery run and popped them in the cabinet or on the counter. A few days later — or, uh, longer — you go to pull them out and there they are: green or sprouted spuds.
Green potatoes. We’re already familiar with the characteristic green tint of chlorophyll in plants, which is essential for photosynthesis, or the process by which they use light to help feed themselves. Potatoes exposed to light can turn green to maximize the opportunity. “But in potatoes, something a little extra, and a little dangerous, happens, too,” Rachael Jackson of the website Eat or Toss wrote for Voraciously in 2019. “Natural or artificial light prompts the creation of defensive toxins called glycoalkaloids that can cause digestive distress, headaches and neurological issues if consumed in significant volumes.”
Advised Jackson, “But before you pitch your potatoes at the first hint of green, consider that such glycoalkaloids naturally occur in potatoes at harmless levels and even contribute to flavor.” Moreover, Nora Olsen, potato specialist for the University of Idaho, told Jackson that potatoes here are already bred for low glycoalkaloid content.
The solution for avoiding greening is pretty simple: Store your potatoes in a dark, ideally cool, spot. A root cellar or chilly basement is great, otherwise aim for somewhere in the cabinet or pantry.
Sprouted potatoes. Potatoes want to grow new potatoes, so under certain conditions they will begin to sprout, says Jang Ho Kim, assistant professor and extension consumer food safety specialist at the University of Idaho. Like green spots, the sprouts can include glycoalkaloids you don’t necessarily want to load up on.
Warmer temperatures and high humidity can elicit sprouting, another reason cool, dark spots are recommended for potato storage. Kim recommends keeping the potatoes in a place that provides some air ventilation while preventing the potatoes from drying out, such as baskets, cardboard boxes, cotton or muslin bags or a wooden box. And separate potatoes from onions, which are another cause of sprouting.
Can you eat them? Green spots and sprouts contain more toxins than the potato itself, according to Kim.
“These toxins cannot be destroyed by cooking but eliminated by removing” the green or sprouted portions before cooking, Kim says.
Keep in mind that you would have to consume large amounts of these toxins to experience ill effects. “Additionally, the human body tends to excrete the toxins quickly, without incident, and you’ll probably notice a bitter taste on the first bite of any seriously glycoalkaloid-riddled tubers,” Jackson wrote.
Olsen told Jackson that you can cut off lightly greened patches and toss any potatoes with large green areas, though you may want to be more conservative when serving children. Rub off small sprouts while you’re scrubbing the potatoes under clean, cool running water — please, no soap! — but any bigger sprouts and their “eyes” should be cut out. Your vegetable peeler may be equipped with a little nub at the end to help facilitate sprout removal. A small paring knife can get the job done as well.
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