What is kosher food?

The meaning of the word

Kasher means “fit” or “proper”. The laws of kashrut come from the Torah – mainly Leviticus 11 and Deuteronomy 14 – and were explained in the Talmud and the Shulchan Aruch.

Animals, birds and fish

A mammal is kosher if it both chews the cud and has fully split hooves (Leviticus 11:3): cows, sheep, goats and deer are permitted; pigs, rabbits, horses and camels are not. Fish need fins and scales (Leviticus 11:9), so salmon and tuna are kosher, while shellfish, shrimp and catfish are not. The Torah lists forbidden birds; in practice only birds with a tradition of being kosher – chicken, turkey, duck, goose – are eaten. Insects are forbidden, except certain locusts by some traditions.

Slaughter and preparation

Meat and poultry must be slaughtered by shechitah, a swift cut by a trained slaughterer, and checked for defects. Blood is forbidden, so the meat is soaked and salted, and certain fats and the sciatic nerve are removed.

Meat and milk

The Torah says three times: “You shall not cook a kid in its mother’s milk.” From this the sages learned that meat and dairy may not be cooked or eaten together, and kosher kitchens keep separate dishes. Foods that are neither – fish, eggs, fruit, vegetables, grains – are pareve and go with either.

Products

Processed food needs supervision, since ingredients like gelatin, wine, cheese rennet or flavourings can be non-kosher. That is the role of kosher certification symbols on packaging.