Observant Jews follow the laws of "kashruth" by observing prohibitions of eating or mixing specific food products or categories of food. These statutes have their basis in the Torah, the first five books of the Old Testament of the Bible. Throughout the millennia, Jewish rabbis and authorities have refined these laws to enable Jews to understand the strictures that, they believe, God expects the Jewish people to observe.
Meat and Poultry
Jews who keep kosher must not eat meat from any animal that does not chew its cud and have split hooves, according to Leviticus 11:3. This includes pig, camel and rabbit, while cow, sheep, goat and deer meat is acceptable. Poultry, including chicken, duck and goose, is kosher. In addition, an animal or bird must have undergone specific "shechitah," or slaughter, by a ritual slaughterer who is familiar with the laws of kashrut. Meat must soak and sit covered in salt for several hours to drain any excess blood to receive kosher certification.
Keeping kosher involves eating only fish with scales and fins. Observant Jews may eat fish such as sole, flounder, bass and perch but may not eat any shellfish, such as lobsters and shrimp, nor other seafood that does not have fins and easily removable scales. Nonkosher fish include catfish, dogfish and sailfish.
Mixing Meat and Dairy
Jews who keep the laws of kashrut will not eat meat and milk products at the same meal, based on the biblical prohibition against boiling a kid in its mother's milk, mentioned in Exodus 23:19 and elsewhere. Observant Jews will also not eat meat or poultry cooked or served in cookware previously used for dairy products and vice versa. Customs vary, but most Jews wait at least three hours after eating meat before they will eat anything with dairy. The waiting period is less after eating dairy because it takes less time to digest dairy products. Foods such as fish, nondairy baked goods and fresh produce are considered "pareve," meaning they are neither milk nor meat, but may be eaten with either.
Insects and Reptiles
Jews may not eat insects or reptiles. Observant Jews will carefully check green leafy vegetables to ensure that they do not have any insects attached to them. Alternately, Jews keeping kosher may purchase bug-free certified packages of vegetables or fruits that are prone to insects, including broccoli, cauliflower, strawberries, raspberries, lettuce and cabbage. Some Yemenite Jews maintain an oral tradition that relates which locusts are kosher, but according to rabbinic law, only Jews who come from Yemenite ancestry may eat locusts.