Potatoes With Green Discoloration

Question:

 I had a fantastic crop of potatoes this year. However, I noticed that some of the potato skins had areas with a green discoloration. I've been told they're poisonous. Should I discard the green potatoes?    

Answer:

  •  Potatoes are an edible tuber that forms underground. It's important to keep the tubers covered during the growing season so that the maturing potatoes are not exposed to sunlight.
  • The potato skin turns a green or a greenish blue color when exposed to light.  The damaged area could be large or small depending on the exposure.
  • The green portion of the skin contains toxins and should not be eaten, but this isn't the issue. The greenish coloration is merely a sign that a potato has been exposed to light, prompting it to produce more chlorophyll, and chlorophyll is not toxic to humans.
  • What creates the problem is that the light exposure also produces a substance called solanine, a glycoalkaloid, which has been shown to be toxic when consumed in significant quantities.
    • Solanine is a natural defense mechanism of a potato to ward off fungus and pests. It can also be triggered when a potato is bruised. Since solanine collects only under the skin and not throughout the potato, it is safe to peel away the skin and a thin layer of white flesh before cooking; however, I would discard any potato that is entirely green.
    • Again, this is an individual problem that doesn't affect the other potatoes you harvested, so enjoy them. 
  •   Potatoes should be stored in a cool dark location. I'd used a brown paper bags or a cardboard box and then covered them with newspaper. Dark or amber plastic bags can be used; however, you'll need to punch holes in the bag for air circulation to prevent moisture from collecting.
  • This keeps the potatoes dry and prevents mold from forming. The kitchen counter is not an ideal location except for a short-term use. 
  • Next year when you plant, you avoid the problem by adding potting soil or other types of organic matter to cover the seed potatoes as they grow. This is sometimes referred to as 'Hilling,' and it's not unusual to add a foot or more of material during the growing cycle.                                         

Note:

Scientists have determined that an adult would have to eat about four and a half pounds of light-exposed potatoes to reach toxic levels of solanine. Potatoes are, to a certain degree poisonous, though not in a deadly manner, and usually not enough to make anyone sick. The leaves of the potato plant contain high levels of a toxin and are direct relatives of the deadly nightshade plant, but so are tomatoes. In the US, it has been over fifty years since anyone has succumbed to potato poisoning, so the risk is very low. And finally, according to Wikipedia, deep-frying green potatoes at high temperature, three hundred and sixty degrees, effectively lowers the level of toxins while boiling them at two hundred twelve degrees is ineffective.