Can cooked potatoes be refrigerated or are they toxic?

It is a misconception that cooked and refrigerated potatoes are toxic. The ISS explains why and how to store the tubers

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Are potatoes stored for several days toxic? In reality it is a false myth, as confirmed by the Istituto Superiore di Sanità. A real problem, but limited only to some cases, is that of solanine.

It can happen to cook too many potatoes and then to keep part of them in the refrigerator for the following days. However, many people believe that this is a dangerous practice as potatoes, not eaten immediately after cooking, can become toxic.

However, this is only a false belief probably due to the fact that potatoes, once cooked, tend to become dark. However, this certainly occurs not because some dangerous microorganism is developing but due to a natural oxidation process.

In practice, potatoes can turn their color towards gray-black (but this does not always happen) as, in the presence of oxygen, the iron contained in them reacts with chlorogenic acid, a substance that defends the tubers from harmful microorganisms .

However, the darker color of potatoes after cooking has no possible harmful effect on our health and we can safely consume them.

And what about the solanine present in these tubers? On this point, the ISS specifies that glycoalkaloids (α-caconine and α-solanine):

In the tubers, that is, in the potatoes we eat, they are concentrated mainly in the skin, in particular, in the tubers exposed to the sun and in the old, wrinkled and with many sprouts. Common cooking techniques, such as boiling or microwaving, do not seem to make substantial changes in the concentration of glycoalkaloids, while frying, thanks to the high temperature reached during cooking, manages to decrease its concentration. The only sure way to decrease the amount of these toxic substances is to remove the skin from the tuber, both on the raw product and after cooking. In any case, in commercial varieties the glycoalkaloid content found is less than 100 mg / kg or in any case less than 200 mg / kg of fresh pulp, a precautionary limit set by the FAO / WHO commission of experts.

The Istituto Superiore di Sanità provides us with some important ones Tips for the best preservation of raw or cooked potatoes:

when still raw they must be kept in the dark and in a dry place
they must be consumed before they sprout
after cooking, they must be kept in the refrigerator and eaten within a few days
to avoid possible toxicity it is better to always remove the peel

Read all of our articles on potatoes.

Source: ISS