How to identify poisonous potatoes?
Written by
Julia Anderson
Reviewed by
Prof. Martin Thorne, Ph.D.Potatoes form solanine toxins when exposed to light, resulting in green spots that are highly toxic. This is a defense mechanism to make tubers toxic to humans. I got sick once when I ate slightly green potatoes, thinking cooking would eliminate the toxins. Solanine produces neurological symptoms even in tiny amounts.
Visual Indicators
- Distinct green tinting on skin and flesh areas
- Extensive sprouting from potato eyes
- Shriveled or wrinkled surfaces indicating decay
Physical Characteristics
- Bitter taste when raw sample is tested
- Unusually soft or spongy texture
- Discolored flesh beneath the skin surface
Risk Factors
- Light exposure during growth or storage
- Damage allowing light penetration to flesh
- Warm temperatures accelerating toxin production
Solanine concentration guides toxicity levels. Green potatoes contain a 250 to 500mg/kg difference, whereas normal potatoes contain less than 20mg/kg. Above 30mg can result in nausea and headache. I now discard any potato that shows even the slightest hint of green, based on my prior experience.
Prevent greening by properly storing potatoes. Store potatoes in total darkness at ideal temperatures of 40-45°F. I use burlap sacks in a cellar - no plastic bags that might hold in moisture. Inspect stored potatoes every 2 weeks and remove those that show any signs of color change.
You can't cook off solanine toxins. Cooking reduces levels enough to make them safe to eat, but not enough to brag about at the dinner table. Never feed green potatoes to animals. My rule of thumb is: when in doubt throw it out. It's a foolproof philosophy for food safety for my family!
Read the full article: 7 Essential Signs When to Harvest Potatoes
