Green Potatoes, Is It Safe to Eat?

Potatoes, delicious in the summer, are a food rich in nutrients such as Vitamin C, potassium, phosphorus, and iron. They are highly versatile and used as an ingredient in various dishes; however, when preparing them, you may sometimes notice that the skin has turned unusually green. In such cases, you might worry about whether the potatoes are safe to eat. Are they okay?

 

Potatoes usually turn green when exposed to sunlight for a long period of time as chlorophyll synthesis occurs.

 

This phenomenon of potatoes turning green is called "greening." Potatoes are crops formed by the enlargement of stems underground; while these stems form potatoes when underground, they revert directly back to stems without forming potatoes when exposed to sunlight. This is due to the synthesis of chlorophyll. Potatoes also turn green if exposed to artificial lighting for extended periods, even without sunlight. This is also why potatoes are covered with newspaper in supermarkets and markets. Greening typically occurs immediately after harvest or during storage and distribution.

The problem is that when potatoes turn green, the content of solanine, a toxic substance, increases. In particular, the glycoalkaloid components of solanine cause a bitter taste. The severity of this bitterness varies depending on the extent of greening, and high concentrations of glycoalkaloids can even induce nausea and allergic reactions. According to the National Institute of Food Science and Technology's "Packaging Technology for Washed Potatoes to Reduce Greening and Spoilage," glycoalkaloid components produce the characteristic potato aroma and bitter taste at low levels (15 mg/100g FW or less), while high concentrations can lead to nausea, coma, and even death. The U.S. Food and Drug Administration strictly limits glycoalkaloid content to 20 mg/100g FW or less. The same applies to sprouted potatoes. It is known that sprouted and discolored potatoes contain more than 10 times the amount of solanine compared to regular potatoes.

 

If a potato has turned green or sprouted, it is safe not to eat it.

 

Solanine is heat-resistant, so it does not easily disappear even if discolored parts or sprouts are cut off and the potatoes are cooked in hot water. When storing potatoes, they should be kept away from sunlight or artificial lighting for extended periods. After purchasing potatoes, storing them in a black bag, newspaper, or box will allow them to be kept for a long time without spoiling. The ideal storage temperature is 7 to 10 degrees Celsius, and if stored at room temperature above 10 degrees, they should not be kept for more than one week.

 

=============

Storing potatoes is really difficult.

When you first dig up potatoes

They also turn green when exposed to sunlight.

 

So, we store it in newspaper or in a shaded place.

 

Nowadays, people even put newspaper inside cardboard boxes to store them.

Sprouts have come out, so I need to tidy them up.