What is the reason why the potato skin is blue?

When potatoes are exposed to the sun for a long time, when the skin turns green or germinates, a lot of solanine will be produced, which is a very toxic substance. If people eat sprouted potatoes, they will have poisoning symptoms such as nausea, vomiting, dizziness and diarrhea. In severe cases, they will also cause paralysis of the heart and respiratory organs, leading to death.

What is Solanum nigrum:

solanine

Solanine is a toxic substance in potatoes, also known as potato toxin (also found in eggplant and immature tomatoes), and it is a toxic glycoside alkaloid. Soluble in water, corrosive and hemolytic, but can be decomposed and destroyed when heated by acetic acid. Generally, every100g of potato contains only about10mg of solanine, which will not cause poisoning. However, in immature potatoes or potatoes whose skins turn green and germinate due to sunlight during storage, the content of solanine can be as high as 500 mg per 100 g, which can cause acute poisoning if eaten in large quantities.