Are green potatoes safe to eat

RATGEBER / 207: How toxic green potatoes are (SB)


No more rumors ...

... that green potatoes are simply inedible

and why the green color and a bitter taste can say something about the tolerance


If you still peel and prepare potatoes yourself, you will occasionally come across green spots on one side of the white or yellow pulp. While our grandmothers knew exactly how to handle such potatoes, today's quality-spoiled consumers are mostly unsettled.

Many who have heard or remembered one or the other rumor, but do not know anything, have confirmed the suspicion that green potatoes, like green moldy bread, are simply inedible or poisonous. The intensity of the green is then mostly taken as an indication of the amount of poison. But since nobody knows exactly what kind of poison it is and how harmful it is for the human organism, it is better to throw green potatoes straight into the garbage disposal.

Others consider this behavior to be grossly exaggerated and the rumors about green potatoes to be a legend that is no longer true these days. Since green things (apart from mold) are generally considered healthy, they don't care about such external characteristics.

The latter are strengthened by numerous new varieties or so-called lifestyle potatoes in all possible colors and shapes, which not only look strange, but are also particularly expensive and still taste good.

In view of rising food prices, however, it could be necessary again to know exactly about the edibility of potatoes and how to treat green potatoes in the most sensible way.

In fact, the poison thing isn't a rumor. Green potatoes contain higher concentrations of a certain toxin, the so-called solanine, which can be responsible for nausea, headaches and minor neurological complaints.

The plant defends itself with a low concentration of the poison, which is also contained in all potatoes, against its predators, i.e. above all potato-loving insects, but ultimately also against humans. As soon as it gets hold of the popular, underground-growing tuber, i.e. digs it out of its natural, earthy environment, exposes it to daylight and warmth, the normal concentration of solanine continues to rise.

Strictly speaking, the green color has absolutely nothing to do with the poison. It is caused by the sudden production of chlorophyll, which the tuber uses to respond to sunlight. And that is an extremely normal reaction that is typical of all plants.

In fact, the intensity of the green is an indication of the concentration of solanine, as the production of chlorophyll also stimulates all of the plant's other metabolic processes, including solanine production.

As far as toxicity is concerned, the slight discomfort that green potatoes can cause can hardly be distinguished from the normal stressful and everyday complaints. In the meantime, however, there are even scientific studies on acceptable limit values.

According to Professor Alexander Pawlista of the University of Nebraska, Lincoln, a 45-pound lightweight can eat about 450 grams of a thoroughly green potato before he gets sick. That's close to a pound, the equivalent of a daily ration of potatoes, but they're usually never completely green. Again: per kilogram of body weight, an average of 10 grams of totally green potatoes are tolerated. With a normal weight of 70 kilos, that amounts to 700 g. So humans can tolerate a lot of this toxin.

Potato farmers and traders generally make sure that there is nothing green under their goods. Green potatoes are thrown in the garbage when they are weighed. If you still find greenish things in your potatoes, you have usually stored them incorrectly:

Potatoes should be kept in a cool, dark place, like the soil they came from. That is why potato stocks used to be "cellarized", i.e. transported to a well-ventilated but dark potato cellar.

To be on the safe side, you should simply cut off the green, solanine-containing parts of the potato when you peel it. Then you can safely eat the rest of the potato.

Another important and often forgotten rule of thumb: stay away if something tastes bitter! And that doesn't just apply to potatoes, but also to all other foods. The bitter taste is, so to speak, a warning for all the predators of young vegetables and translates as: Attention, I defend myself with plant poison!

In summary: Green potatoes contain a vegetable toxin that can cause nausea. However, this can be made harmless by cutting out the green areas of the potato. The potato then remains edible.

July 10, 2007


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