Sweet potatoes are a staple in my kitchen. Whether I’m roasting, mashing, or pureeing them into soup, I spend a lot of time slicing into these tubers. But when I started chopping one the other day, I was surprised (and a tad concerned) to see it leaking a white, milky substance. Obviously, I had to do some investing to figure what the heck was going on – and whether I needed to change my dinner plans.
Like previous issues with sprouted onions, wrinkled bell peppers, or green hard boiled eggs, I was happy to find answers pretty easily. Food blogger Jeremy Hall explains on his website, “Sometimes when you cut into a sweet potato you are going to see a white liquid oozing out of the potato. This is completely safe!”
He adds that the odd-looking substance is just a mixture of the starch and water found inside of the sweet potato. When a knife cuts into the spud, it releases the liquid. Fellow food bloggers at Carnival Nutrition point out that sometimes this reaction happens immediately, but you might not notice it until after the slices have been sitting on your cutting board for awhile.
The milky liquid, or “sap” as some call it, can also show up in other dense, starchy veggies like butternut squash. You can simply wipe it away — or ignore it and continue cooking as normal. I can confirm that it won’t affect the flavor of your food, as mine tasted perfectly fine after I finished making dinner with my own leaking spuds.
Of course, it’s also perfectly normal to have sweet potatoes and other starchy vegetables that don’t have this milky substance at all. The different reactions to slicing likely have to do with the different timing of food being harvested, varying from one supplier to the next.
However, if a sweet potato has been sitting around on your counter for awhile, feels soft to the touch before cooking, or starts leaking a watery brown substance instead, it’s probably gone bad and should not be included in your meals.
Otherwise, dig in and enjoy!