Blackthorn, also called Prunus spinosa by biologists, with its distinctive thorns and its deep dark blue berries, is frequently encountered and accordingly well known. In the past, the fruits of this wild plum species were very popular for juices, liqueurs and jams, and recently they are again enjoying increasing attention. But what is there to the well-known wisdom that the fruit of sloe is poisonous raw and can only be consumed processed?
Are sloes poisonous raw?
First of all, this question can be answered in the affirmative when viewed objectively. The seeds of blackthorn, which is a stone fruit, contain the prussic acid glycoside amygdalin, which is converted to prussic acid in the human body after consumption. However, one should already put this into perspective at this point, since other pome fruit kernels also contain the same substance. The amygdalin content of apple cores or bitter almonds is significantly higher than that of sloe berries. Furthermore, it should be emphasized that the skin and flesh of sloes do not contain this substance and are therefore not toxic and completely harmless from a purely medical point of view. In general, the berries of blackthorn should not be eaten together with the seeds. But even eating individual seeds is considered harmless.
The situation is different for children, especially infants. Your organism is not yet able to break down prussic acid in the required quantity. The consequence of eating sloe seeds is then quickly diarrhea and vomiting!
Note: For animals, especially birds, sloes are completely harmless and non-toxic when raw. Therefore, the thorny shrubs are not only popular retreats and even breeding places of birds, but also an important source of food in the onset of winter.
Sour/ bitter taste
But where does the general and persistent opinion that sloes are poisonous come from?? If you taste a Prunus spinosa berry early in the fall, this question is almost self-answering. When eaten raw, the berries have a very sour and sometimes bitter taste. This taste is caused mainly by the high content of tannic acids in the flesh of the fruit. With regard to the question of the toxicity of the berries, it must be emphasized that although the tannic acids have a strong negative effect on the taste, this is in no way related to any toxicity.
Note: Particularly sensitive people may indeed react to the tannic acid content if consumed in excess. However, this is in no way due to poisonous substances of the sloe, but rather due to a special sensitivity of the individual person.
Again and again one reads that sloes are both laxative and adristingent when eaten raw. As mentioned, the laxative effect occurs only in very sensitive people, or when eating very large quantities of berries. The same is true for the adristingent effect. In medical terms, this is the property of contracting blood vessels. This effect is mainly important for the medical use of the ingredients. It does not need to be considered further when eating "usual" quantities. Since the harvest of sloe is very laborious, the maximum amount of berries consumed should regulate itself anyway.
Nevertheless, there is a possibility to eat the fruit of sloes raw and also to enjoy it. Because if you wait for the first frost, the berries suddenly become tasty without losing their characteristic aroma. But how does this happen, and does it always happen when there is frost??
The change of the fruit flesh content is actually caused by freezing. Because then the tannic acids are broken down and converted into sugar. Thus on the one hand the sour to bitter notes are reduced, while the sweetness increases at the same time.
It should be noted, however, that the change in taste has nothing to do with whether the berries are poisonous. In the end, the frost only makes berries that were previously edible raw edible.
Tip: If frost is a long time coming, you can also put sloe berries in the freezer for some time to simulate natural frost.
Note: Please note that this article in no way replaces a visit to the doctor. There is no guarantee for the correctness of medical statements.
Detailed information on first aid for poisoning and important information on poison control centers can be found here.