The fact is that green tomatoes are poisonous because they contain the alkaloid toxin called solanine.
How does this piece of information fit in with Jon Avnet’s 1991 film “Fried Green Tomatoes” where fried green tomatoes are offered as a speciality in the Whistle Stop Café or the fact that in some regions of Europe, pickled green tomatoes and jams made from – you guesed it, green tomatoes are even considered a delicacy? So are they poisonous or not?
Well its all about how much poison is in the green tomatoes and what the effects of eating them can be.
How poisonous are green tomatoes really?
Since only the green plant parts of the tomato contain the alkaloid, there is only a risk of poisoning when unripe green tomatoes are consumed.
If poisoning does occur, the first serious symptoms would be drowsiness, heavy breathing, stomach problems and diarrhea. This would only occur in adults when they consume about 200 milligrams of solanine. If significantly larger amounts is consumed, it could also cause damage to the the central nervous system, cramps and paralysis. A dose of around 400 milligrams is considered fatal.
Green tomatoes contain around 9 to 32 milligrams per 100 grams. So at those concentrations, one would need to consume over 600 grams of unripe raw tomatoes in order to cause the first signs of poisoning. You would have to agree that it would be very unlikely for someone to do this, especially since solanine tastes very bitter and unpleasant.
Half-ripe tomatoes, that is tomatoes that are about to ripen, only contain 2 milligrams of solanine per 100 grams of tomatoes. At this concentration it would take a mammoth eating session of 10 kilograms of raw half-ripe tomatoes to make it dangerous.
One important note of caution is that solanine is resistant to breakdown from heat so cooked or pickled products made from green tomatoes still contain around 90% of the solanine they contained in their raw form.
Once tomatoes have reached full ripeness, they only contain a maximum of 0.7 milligrams per 100 grams, which would mean that around 29 kilos of raw tomatoes would have to be consumed in order to get into the area of noticeable poisoning.
In summary, due to the bitter taste and the comparatively low concentration in semi-ripe tomatoes, it is relatively unlikely that you will accidentally poison yourself with solanine. However, green tomatoes are pickled and soured in some regions or jams are made from them. These products should be used with caution, as solanine is heat-resistant and the bitter taste is covered by sugar, vinegar and spices. Especially with the variant of the pickled tomatoes, it is assumed that up to 90 percent of the solanine content is still present, which can lead to symptoms of poisoning even when consumed in quantities of 100 to 150 grams.
Green tomatoes contain the toxic alkaloid solanine
Solanine is one of the alkaloids. This chemical group includes several thousand active substances, which are mostly contained in plants as antibodies. They include, for example, the colchicine of the autumn timeless , which can be lethal in small doses, and the strychnine of the walnut. However, this group also includes capsaicin, which is responsible for the spiciness in chilli and hot peppers , or the morphine of the sleep monkey, which is used in pain therapy. In small doses of a few milligrams, many of the substances are used in medicine. It usually becomes dangerous if the parts of the plants containing the substances are consumed in large quantities or otherwise consumed.
The protection mechanisms of immature fruit plants
When it comes to protecting yourself from predators in the plant world, fruit-bearing plants in particular take special precautions. With the tomato, it’s camouflage and a chemical cocktail. The unripe fruits are green and therefore more difficult to see between the leaves of the plant. Only when the fruits and the seeds they contain have ripened far enough so that they can ensure the propagation of the tomato do they turn red or yellow, depending on the variety. All kinds of things also happen inside the fruit during the ripening process. The green tomatoes contain the toxic alkaloid solanine. It provides a defensive bitter taste and if the unripe fruit is still eaten in large quantities, poisoning symptoms soon appear.