In Hebrew, the word kosher (or kosher) means “fit,” “correct,” or “proper.” Although today it is usually associated almost exclusively with food, in Jewish tradition this concept has a much broader meaning: something kosher is something that complies with the rules or precepts dictated by the Torah or rabbinic authorities. Thus, we can speak of a kosher business, kosher behavior, or, of course, kosher food.
The rules that determine what is considered kosher are known as kashrut. These rules are found primarily in the Torah, the sacred text of Judaism, and are subject to a millennia-old rabbinic interpretation, primarily reflected in the Talmud. Therefore, what is considered permissible or prohibited is not the result of a simple arbitrary decision, but the result of a dense legislative and spiritual framework.
For practicing Jews, Following the laws of kashrut is an everyday way of consecrating the most ordinary acts, such as eating, elevating them to a spiritual and communal dimension. In addition to providing religious meaning to daily life, these rules have historically helped to shape a clear collective identity and maintain the cohesion of the Jewish community throughout centuries and diasporas.
Biblical and rabbinic bases of animal kashrut
The main rules on which animals can be consumed appear in the books of Leviticus and Deuteronomy. In these texts, the Torah establishes clear and detailed categories for mammals, birds, fish, and insects, differentiating between those species that are "pure" (fit for consumption) and those that are "impure" (forbidden).
Kashrut not only regulates the permitted species, but also their slaughter, processing, and the non-mixing of certain food groups. According to tradition, many of these laws seek to promote a purer, more ethical, and disciplined life; others have a symbolic, moral, or spiritual function, and some may have originally had practical or health-related justifications.
In addition to the Torah, the Talmud is responsible for developing and clarifying these precepts, providing a multitude of details and clarifications that have shaped the rich and sometimes complex kosher practice of today.
Classification of animals according to kashrut
The Torah divides animals into four broad categories:
- Land mammals (behemoth and jaiot)
- Fish and aquatic animals
- Birds
- Sheratzim (a term that covers reptiles, insects, worms, and other small terrestrial creatures)
In all these families there are species suitable for food and others that are strictly prohibited, with specific criteria for each group.
Permitted and prohibited mammals: the two key signals
The fundamental rule for mammals is that only those that meet two simultaneous conditions can be consumed: to be ruminants and have the split or cloven hoof.
This means that only herbivorous animals, with a digestive system adapted to rumination and with hooves completely divided in two, can be considered kosher. Clear examples of permitted species are:
- Cow
- Sheep
- Goat
- Antelope
- Carnero
- Red deer (in some traditions)
- Buffalo (also in certain communities)
On the contrary, most mammals are excluded from the kosher diet by not meeting both signs. Some Examples of prohibited species are:
- Pork (it has a split hoof, but it is not a ruminant)
- Camel (chews the cud, but does not have a split hoof)
- Horse
- Leporidae (hare, rabbit)
- Donkey
- Dog and cat
- Lion, tiger, bear, elephant
- Monkey, cheetah, panther, lynx, wolf, fox
- Others: squirrel, kangaroo, platypus, dolphin, seal
The consumption of any product derived from these animals (milk, eggs, fat, etc.) It is also prohibited, with the exception of honey, which is accepted by most currents.
The ban extends to sick animals, those that died of natural causes, or those that have internal defects when slaughtered. Only perfectly healthy animals slaughtered according to the ritual may be consumed.
Kosher Poultry: Criteria and Particularities
The Torah lists 24 forbidden species of birds, most of which are birds of prey or scavengers. Unlike mammals, there is no specific universal rule based on physical characteristics that identifies which birds are permissible, so tradition and rabbinic observation play a key role.
Some physical signs cited by tradition and the Mishnah to identify kosher birds are:
- Presence of a prominent hind toe (or longer front toe)
- To have a crop (digestive storage organ)
- Possess gizzard covered by an internal membrane that can be separated
In addition, any bird of prey or meat-eating birds is prohibited, with the premise that the permitted species are mostly granivorous.
In practice, only those birds are consumed for which there is an established tradition of permissibility, passed down from generation to generation. Among the birds recognized as kosher are:
- Chicken
- Turkey (with some discrepancies, since it does not appear in biblical sources, but it has been accepted in much of the current Jewish world)
- Duck
- Goose
- Gallina
- Paloma
- Pigeons (for its use in sacred offerings)
Among the prohibited birds are: vulture, falcon, owl, ostrich, eagle, crow, owl, stork, hoopoe, pheasant and any bird of prey or scavenger.
When in doubt about new species or hybrids, caution is generally exercised and they are avoided unless there is a clear tradition of permissibility.
Fish and aquatic animals: fins and scales as identifying marks
For a fish or aquatic animal to be considered kosher, it must have fins and scales. Both attributes must be visibly present, even if minimal. This dual characteristic is the only one recognized and accepted by tradition; no fish without both can be considered kosher.
Some of the most common kosher fish are: tuna, salmon, carp, hake, sole, herring, mackerel, trout, sardine, sea bass.
On the contrary, the following are automatically excluded from consumption: All shellfish (lobsters, shrimp, prawns, crabs, oysters, clams, octopus), sharks, catfish, stingrays, eels, whales, dolphins, and any marine creature without scales or fins are also prohibited. Eggs and products derived from non-kosher species (e.g., sturgeon caviar) are also prohibited.
Insects and small animals: a surprising exception
Almost all insects, reptiles, amphibians and small crawling animals are strictly prohibited by kashrut. However, there is one exception that may be surprising: according to the Torah and rabbinic tradition, some species of grasshoppers and locusts (referring to the insect, not the crustacean) are permitted, provided they meet very specific distinctive features and there is an unbroken tradition of their consumption, as has been the case among the Jewish communities of Yemen and Morocco.
However, the enormous difficulty in accurately identifying these species has led, in practice, the vast majority of Jews to avoid eating any insect.
Rodents, reptiles (snakes, lizards, chameleons, turtles), amphibians (toads, frogs), worms and other small terrestrial animals are also prohibited.
Derivative products and the nuances of tradition
The kosher prohibition extends to all products derived from prohibited animals: milk, eggs, fat, gelatin, oils and any other by-products. The only traditionally accepted exception is honey bee, which is considered kosher because it comes from flower nectar, and the bee's work is solely storage and processing, not direct generation. This exception has been discussed in rabbinic literature, but it is widely accepted.
Fruits, vegetables, grains, and plant products in general are considered neutral (parve), but they should be carefully inspected for the accidental presence of insects, since even a small amount of bugs in a food could invalidate its kosher status.
