What is Solanine?:
Solanine is a poisonous substance that occurs naturally in potatoes and other members of the nightshade family, such as tomatoes and eggplants. A very small amount of solanine can be toxic, and in very large doses it can be fatal.
Signs of Solanine:
In potatoes, the skin will turn green and there will be a very bitter flavor. Symptoms of solanine poisoning include diarrhea and vomiting.
Preventing Solanine Poisoning:
One of the triggers for solanine to develop in a potato is exposure to light. especially fluorescent light. Therefore, it's always best to store potatoes in a dark place, preferably between 50°F and 65°F. If potatoes must be stored in a lighted place, it's best to keep them in a brown paper bag loosely closed to allow for air circulation.
Dealing with Solanine in Potatoes:
If green discoloration is seen on a potato, the green areas can be cut off, but for safety's sake, it's probably best to discard the whole thing. Deep-frying a potato in oil that's hotter than 320°F will render the solanine harmless.