Brown Spots On Baked Potatoes Aren't Necessarily Unsafe - Tasting Table

"You really don't need much to make a delicious baked potato - some oil, a little salt, and an oven rack - and the opportunity to make it into a meal is endless. But at the crux of it all, of course, is the potato itself. Even a delicious baking potato can have flaws, and if you notice that yours has some brown spots, there's usually no need to worry."

"It's common to find black or brown spots underneath the skins of potatoes, and they are typically harmless. Different from the freckle-like dots on a potato, which are the plant's lenticels, or "breathing holes", this phenomenon is known as Black Spot Bruising or Internal Black Discoloration and it can occur for a number of reasons. The first is that the potatoes were stored at a temperature of below 40 degrees Fahrenheit."

"The potatoes may also have been stored too close together for a long period of time, or the problem may lie in the amount of calcium they contained during growth (this particular issue is known as Internal Brown Spot). If the browning was caused by any of these factors, you can think of the spots a bit like human bruises - it's just a little discoloration and tenderness. All you need to do is cut the spots off either before or after cooking."

Black or brown spots under potato skins are typically harmless and are called Black Spot Bruising or Internal Black Discoloration. Cold storage below 40°F causes starch to convert to sugar, producing discoloration and a slightly sweeter cooked taste. Physical impact during harvest, transit, or handling can cause internal bruising. Long, crowded storage or low calcium during growth can create Internal Brown Spot, producing tender, discolored patches. Small discolored areas can be trimmed away before or after cooking. Extensive discoloration or signs of fusarium may indicate a more serious quality issue that warrants caution.

Read at Tasting Table