Green Spots on Potatoes Signal Potential Toxins, Cooking Won't Remove Them

A small green spot on a potato is often dismissed by peeling it off, but this can be misleading. The green color indicates exposure to light, causing the potato to produce chlorophyll and potentially harmful glycoalkaloids like solanine and chaconine. These natural toxins are concentrated in the skin, sprouts, and eyes of the potato and are not significantly reduced by cooking, baking, or frying.

Health authorities such as Health Canada and Germany's Federal Institute for Risk Assessment recommend thoroughly removing green areas, sprouts, and damaged parts before consumption. If the green spot is small and the potato remains firm and fresh without a bitter taste, peeling generously can make it safe to eat. However, if the potato is old, soft, shriveled, extensively green, heavily sprouted, or shows signs of rot, it should be discarded.

A common mistake is peeling too thinly or assuming cooking will eliminate the toxins, which is incorrect. Additionally, the cooking water from such potatoes should not be reused, as toxins can leach into it. To prevent greening, potatoes should be stored in a cool, dry, and dark place away from light and transparent bags. Noticing bitterness or a burning sensation when tasting is a clear warning to avoid eating the potato.

In summary, green spots on potatoes are a health risk indicator that requires careful handling and sometimes disposal, rather than simply peeling or cooking as usual.