Green Spuds: Why It Happens

If your potatoes are turning green in the pan, it's likely due to exposure to light during growth, storage, or cooking. The green colour comes from chlorophyll, a pigment that develops in the skin of the potato. While chlorophyll itself is harmless, the presence of green on a potato can indicate the formation of solanine, a toxic compound that can cause digestive issues if consumed in high quantities. To prevent potatoes from turning green, store them in a cool, dark, dry location, away from direct light and heat sources. When preparing green potatoes, trim away any small green spots, sprouts, or eyes, and avoid serving them to young children, who are more susceptible to solanine poisoning.

Chlorophyll and its role in the greening of potatoes

Chlorophyll is a natural plant pigment that gives many plants and algae their colour. It is responsible for the green colour observed in potatoes. When potatoes are exposed to light, they produce chlorophyll, which turns them green. This process occurs in both light-skinned and dark-skinned potatoes, although it may be less noticeable in the latter due to the presence of dark pigments.

Chlorophyll plays a crucial role in photosynthesis, allowing plants to harvest energy from sunlight. Through photosynthesis, plants can produce carbohydrates and oxygen from sunlight, water, and carbon dioxide.

While chlorophyll itself is harmless, its presence in potatoes can indicate the accumulation of toxic compounds, particularly glycoalkaloids (GAs) and solanine. These compounds are naturally produced by potatoes to protect against insects, bacteria, and fungi. However, they can be harmful to humans if consumed in high doses.

The formation of chlorophyll and GAs in potatoes is influenced by various factors, including genetic traits, nutrient content, and post-harvest conditions such as exposure to light, moisture, and packaging.

To prevent potatoes from turning green, it is important to store them in a cool, dark place with good air circulation and high humidity. Additionally, careful handling and proper storage can help reduce the production of solanine, another toxic compound found in potatoes.

In summary, chlorophyll plays a vital role in the greening of potatoes and is essential for photosynthesis. While chlorophyll is harmless, its presence in potatoes can indicate the accumulation of toxic compounds. Proper storage and handling are crucial to prevent greening and maintain the safety of potato consumption.

Solanine and its effects on the body

Solanine is a toxic glycoalkaloid compound that occurs naturally in the nightshade family of plants, including potatoes, tomatoes, and eggplants. It is produced as a defence mechanism against insects, bacteria, and fungi. When potatoes are exposed to light, they produce chlorophyll, which turns them green. This process can also stimulate the production of solanine.

Solanine poisoning can cause gastrointestinal and neurological issues. Symptoms include nausea, vomiting, stomach cramps, diarrhoea, burning of the throat, cardiac dysrhythmia, headaches, dizziness, itching, eczema, thyroid problems, and joint pain. In severe cases, it can cause hallucinations, paralysis, fever, hypothermia, and even death.

The toxicity of solanine depends on various factors, such as body weight, age, and overall health. The toxic dose is generally considered to be 1 mg or more of solanine per kilogram of body weight. However, the fatal dose is estimated to be around 3-6 mg/kg.

To avoid solanine poisoning, it is recommended to:

• Store potatoes in a cool, dark place to prevent greening and reduce solanine production.
• Avoid eating green or unripe nightshade vegetables.
• Remove green parts, shoots, and leaves from nightshade vegetables before consumption.
• Properly store nightshade vegetables to prevent the formation of solanine.
• Avoid eating spoiled or mouldy nightshade vegetables.
• Wash nightshade vegetables thoroughly before consumption.

How to prevent potatoes from turning green

Potatoes turn green when they are exposed to light, either during their growth or storage. This greening is caused by the formation of chlorophyll, which is harmless in and of itself. However, the presence of chlorophyll also indicates the production of glycoalkaloids, specifically solanine, which is toxic to humans in high doses. To prevent your potatoes from turning green, follow these steps:

Plant at the Proper Depth:

Potatoes should be planted at a depth of about 4-6 inches. This will help shield them from the sun's rays and reduce the likelihood of greening.

Hill Your Potatoes:

Ensure that sufficient soil is mounded around each plant. This process is known as "hilling" and helps to protect the developing tubers from sunlight. Build a small hill around your plant, as the height will naturally reduce over time due to rain or irrigation.

Store Properly and Avoid Light Exposure:

Keep potatoes in a cool, dark, dry location, preferably between 45 and 50 degrees Fahrenheit. The storage area should be well-ventilated and have good air circulation. Eliminate exposure to artificial light during storage and keep them away from heat sources such as appliances. If you plan to consume the potatoes soon, you can store them in a paper bag in a cupboard.

Inspect Before Purchasing:

When buying potatoes, check for any signs of greening or sprouting. Avoid potatoes with green colouring, shrivelled skin, or sprouts as these are more likely to have higher levels of solanine.

Cure Before Storing:

Before storing your harvested potatoes, ensure they are properly cured. The skins should be impenetrable by your fingernail, indicating they are ready for storage.

By following these steps, you can effectively reduce the chances of your potatoes turning green and maintain their quality and safety for consumption.

How to prepare green potatoes for consumption

Green potatoes are usually safe to eat when prepared properly. The green colour and bitter taste that potatoes develop can indicate the presence of a toxin called solanine, which can cause digestive symptoms if consumed in large amounts. However, it is important to note that the green colour itself is not harmful, it is the result of chlorophyll production, which is non-toxic and potentially beneficial to human health.

• Inspect the potatoes before purchasing them: Check for any green colouring, shrivelled skin, or sprouted areas. These are signs of poor quality and indicate that the potatoes may have been exposed to light or damaged.
• Store potatoes properly: Keep potatoes in a cool, dark, dry location, preferably between 45-50 degrees Fahrenheit (45-90% relative humidity). The storage area should be well-ventilated. Potatoes stored in these recommended conditions should remain at their best quality for about a month. Avoid storing potatoes in the refrigerator, as this can actually increase solanine levels.
• Prepare the potatoes for cooking: Trim away any small green spots, sprouts, or "eyes". Remove any green skin by peeling the potatoes. If the flesh is still green beneath the peel, be more aggressive in removing all traces of green.
• Cook the potatoes: Cooking methods such as boiling, baking, microwaving, or frying can help to reduce solanine levels. However, keep in mind that solanine is heat stable and is not destroyed by cooking.
• Taste the cooked potatoes: If the cooked potatoes taste bitter or cause a burning sensation in your mouth or throat, do not eat them as this indicates high levels of solanine.

It is important to note that even with proper preparation, there is still a risk of solanine poisoning, especially in children. If you are concerned about solanine levels, it may be best to discard heavily greened potatoes and choose potatoes with minimal green spots.

Recommended storage methods for potatoes

To prevent potatoes from turning green, it is important to store them properly. Here are some recommended storage methods to keep your potatoes fresh and prevent greening:

• Keep potatoes in a cool, dry, and dark place: The ideal temperature for storing potatoes is between 45°F to 55°F (or around 50°F). Storing them at warmer temperatures can cause sprouting or spoilage, while colder temperatures, like in a refrigerator, can turn their starch into sugar, affecting their taste and texture.
• Choose the right container: Avoid plastic bags as they can trap moisture and create an environment that promotes spoilage. Instead, opt for a paper bag, cardboard box, basket, or bowl, which allow for better air circulation.
• Avoid exposure to light: Potatoes turn green when exposed to sunlight or artificial light. Store them in a dark place, such as a cupboard, pantry, basement, or root cellar.
• Maintain good air circulation: Ensure the storage area has proper ventilation to prevent moisture buildup.
• Keep potatoes away from certain produce: Potatoes should not be stored with onions, bananas, or apples, as these produce ethylene gas, which can cause potatoes to ripen and spoil faster.
• Inspect and prepare potatoes before storage: Before storing, check potatoes for any signs of damage or greening. Avoid storing potatoes with cracks or exposed areas, as light can enter and cause greening.
• Store potatoes separately: Store potatoes in a single layer, if possible, and keep them away from other potatoes that may be sprouting or spoiling.
• Consume or preserve potatoes: If you have more potatoes than you can consume before they start to sprout, consider preserving them through methods like freezing or dehydration.

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