Updated: Apr 21, 2020
Are they Poisonous or Harmless?
Many times we must have noticed the green part of the potatoes and always ignored. Exposing the potatoes to light either in the field, in storage, on grocery store shelves or at home can cause pigmentation on the surface as well as the inner parts of the potatoes. The “greening” is due to the formation of Chlorophyll, pigments found on green vegetables like mint, spinach, coriander, curry leaves, broccoli, lettuce, and cabbage. Though chlorophyll is harmless and tasteless, this is majorly associated with the formation of Glycoalkaloids, most notable Solanine. Solanine usually is present in low levels in the skin and flesh of potatoes, as well as in higher concentrations in parts of the potato plant. Yet, when exposed to sunlight or damaged, vegetables produce more of it.
Nevertheless, greening is a sign that a potato may be starting to produce more solanine. When exposed to light, potatoes provide a toxin called solanine. It protects them from insects and bacteria, but it’s toxic to humans. Greening in vegetables is a good indicator of solanine.
According to the FDA, an average person weighing 80kg would have to consume at least an entire kilogram of the affected green areas of the potatoes in a serving to trigger the toxic response. The vegetables with such a level of toxicity will contain bitterness and burning taste that can be unpleasant to consumers.
Image from Garden.co
How can this be prevented?
Check and inspect the potatoes before you buy them. Store them in a cool and dry place. Buy what you need and do not overload. Use them within ten days to avoid them from shrinking, and this could be the initial stages of greening. Peeling the green area of the potatoes can help reduce the solanine levels. Once it has completely turned green, it’s best to discard it — same apply to all roots and tuber vegetables.