Discover why potatoes develop green patches, the hidden risks of eating them, and how to store potatoes safely to prevent greening.
Reading Time: 5 minutes
Category: Kitchen Tips & Food Safety
Topic: Potato Storage, Green Potatoes & Food Safety
Introduction
Why potatoes turn green and what happens if you eat green potatoes is an important food safety question that every home cook should understand. Have you ever reached into your pantry, grabbed a potato, and noticed an unusual green color beneath its skin? It might look harmless, but that green appearance can signal something worth paying attention to. Potatoes naturally change color when exposed to light, and this process can be associated with increased levels of potentially harmful compounds. I'm Ana, and I believe understanding simple kitchen safety tips is just as important as learning delicious recipes. Here's what causes green potatoes, when they become unsafe, and how to prevent the problem.
Why Do Potatoes Turn Green?
Potatoes turn green primarily because they have been exposed to light. When sunlight or artificial light reaches the potato, it stimulates the production of chlorophyll, the same green pigment found in plants.
Chlorophyll itself is harmless. However, light exposure can also increase naturally occurring compounds called glycoalkaloids, especially alpha-solanine and alpha-chaconine.
These compounds help protect potatoes against insects and other threats, but consuming excessive amounts can cause illness.
Important: The green color does not directly measure toxin levels. A potato can contain elevated glycoalkaloids without appearing noticeably green.
What Happens If You Eat Green Potatoes?
Eating potatoes containing high levels of glycoalkaloids can cause gastrointestinal and, in more serious cases, neurological symptoms.
Possible symptoms include:
- Nausea and vomiting
- Stomach cramps or abdominal pain
- Diarrhea
- Headache or dizziness
- Weakness or confusion in more serious cases
Symptoms may begin within several hours, although the timing varies. The severity depends on the amount consumed and the concentration of glycoalkaloids.
Serious poisoning is uncommon, but it can occur. If someone develops significant symptoms after eating questionable potatoes, contact a medical professional or poison control service promptly.
Can You Eat Potatoes That Have Turned Green?
The safest decision depends on how extensively the potato has turned green.
Slight Surface Greening: If a potato has a very small green patch, some food safety guidance allows removing the affected skin and a generous layer of underlying flesh. However, this does not guarantee that all glycoalkaloids have been removed.
Extensive Greening: Discard potatoes with large green areas, especially when the green color extends deeply into the flesh.
Bitter Taste: Never eat potatoes that taste noticeably bitter or produce a burning sensation in the mouth.
Heavy Sprouting: Discard heavily sprouted, shriveled, or deteriorating potatoes, particularly when combined with greening.
When you're uncertain about a potato's safety, throwing it away is the better choice.
Does Cooking Remove the Toxins from Green Potatoes?
Unfortunately, normal cooking does not reliably eliminate potato glycoalkaloids.
Boiling, baking, roasting, and microwaving should not be considered dependable methods for making a heavily green potato safe to eat.
Peeling can reduce glycoalkaloid levels because concentrations are often highest in the skin and nearby tissue. However, peeling cannot guarantee safety when levels are elevated throughout the potato.
Always inspect potatoes before cooking rather than relying on heat to solve the problem.
How to Prevent Potatoes from Turning Green
Proper storage is the easiest way to reduce potato greening and maintain their quality.
- Keep potatoes in darkness: Store them away from direct sunlight and bright kitchen lighting.
- Choose a cool location: A cool pantry or suitable cellar helps slow deterioration.
- Provide ventilation: Use a breathable paper bag, cardboard box, or ventilated basket.
- Avoid excessive moisture: Keep potatoes dry until you're ready to wash and prepare them.
- Inspect regularly: Remove potatoes showing extensive greening, decay, or heavy sprouting.
- Avoid prolonged warm storage: Heat can accelerate sprouting and spoilage.
For everyday home storage, aim for a dark, well-ventilated location at approximately 45–50°F (7–10°C) when available.
Are Green Potatoes and Sprouted Potatoes the Same Problem?
Not exactly. Greening happens when potatoes produce chlorophyll after light exposure, while sprouting occurs when potato buds begin growing.
Both conditions can be associated with increased glycoalkaloid concentrations, particularly around sprouts and eyes.
A firm potato with a tiny sprout and no greening may sometimes be used after thoroughly removing the sprout and surrounding tissue. However, heavily sprouted, soft, shriveled, or green potatoes should be discarded.
Frequently Asked Questions
1. Is the green color in potatoes poisonous?
No. The green pigment is chlorophyll, which is not poisonous. The concern is that conditions causing greening can also increase potentially toxic glycoalkaloids.
2. Can peeling a green potato make it safe?
Peeling removes some glycoalkaloids concentrated near the skin, but it cannot guarantee safety. Discard potatoes with extensive or deep greening.
3. How long does it take for potatoes to turn green?
Potatoes may begin developing green patches after several days of significant light exposure, although the timing depends on light intensity, potato variety, and storage conditions.
Final Thoughts
Understanding why potatoes turn green and what happens if you eat green potatoes can help you make safer choices in the kitchen. Although chlorophyll causes the visible green color, the real concern is the possible buildup of glycoalkaloids. Store potatoes in a cool, dark, ventilated place, inspect them before cooking, and discard those with extensive greening or deterioration.
Remember: When a potato looks suspicious, especially if it's deeply green or tastes bitter, it's better to discard it than risk getting sick.
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