Kashrut

• 1. Introduction

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  Kashrut is the set of Jewish dietary laws that decides which foods a person may eat and how those foods must be prepared under Jewish religious law. The vocabulary alone hints at how much is at stake. A food that may be eaten is kosher, from a word meaning "fit" for consumption. A food that may not be eaten is treif. An object that fails the standard is pasul. Most of the basic rules trace back to the Torah's books of Leviticus and Deuteronomy, yet the Torah itself rarely says why. That silence has kept scholars busy for two thousand years. Why is the pig excluded but the cow welcomed? Why must meat and milk never touch the same plate? Why does a curious little blue or black symbol on a box of crackers matter to millions of shoppers who are not Jewish at all? The answers run from a single quick cut of a knife to a 40-billion-dollar market, from a wrestling match in the book of Genesis to a debate over genetically modified salmon. The rules are numerous and complex, but they rest on a few basic principles, and it is those principles that turn an ordinary kitchen into a place governed by law.

• 2. The Forbidden And The Permitted

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  Only certain mammals, birds, and fish can ever qualify as kosher, and the test for mammals is precise. An animal must both chew its cud and have cloven hooves. One trait without the other is not enough. The camel, the hyrax, and the hare are ruled out because they lack cloven hooves, and the pig is ruled out because it does not ruminate. Birds of prey are excluded, while shellfish and all other non-fish water creatures fail outright. Fish themselves must have both fins and scales, which is why the catfish is forbidden. Invertebrates are off the table with a single strange exception: certain types of locust, the only kosher invertebrate, though most communities lack a clear tradition for identifying them. No reptiles, amphibians, or rodents are kosher, and any animal that eats other animals or has been partly eaten by them is generally barred too. In 2008, a rabbinical ruling settled an unusual question by determining that giraffes and their milk are eligible to be considered kosher. The giraffe has split hooves and chews its cud, and findings that same year showed that giraffe milk curdles, meeting kosher standards. Yet no one slaughters giraffes for food. The process would be very costly, the animals are difficult to restrain, and using them this way could push the species toward becoming endangered. Birds carry their own puzzle. The Torah lists non-kosher birds outright, mentioning 24, but the exact zoological references are disputed. The Mishnah supplies four signs from the sages. A dores, a predatory bird, is not kosher, and a kosher bird must have an extra back toe, a crop, and a gizzard with a peelable lining. Even so, an individual Jew may not simply apply the signs. An established tradition, a masorah, is required before a bird may be eaten. The single exception is the turkey, which Jews began eating without a masorah because it possesses all the signs.

• 3. Blood And The Knife

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  Blood is the most basic eating rule in the Torah: it is not to be consumed. That single prohibition shapes everything about how a kosher animal dies. Mammals and birds must be slaughtered through a process called shechita, carried out by a certified ritual slaughterer known as a shochet. Using an ultra-sharp, unserrated instrument called a chalaf, the shochet severs the trachea, esophagus, carotid arteries, and jugular veins in one quick continuous cut. The result is rapid and massive blood loss. Failure to meet any of these criteria renders the meat non-kosher. The animal's body must then be checked after slaughter. The aim is to confirm it had no medical condition or defect that would have caused it to die on its own within a year. These disqualifying conditions, called treifot, span 70 different categories of injuries, diseases, and abnormalities. A fractured bone or particular types of lung adhesions can render an animal non-kosher. Meat from a kosher animal that was not slaughtered properly becomes carrion, or nevelah, and that includes animals slaughtered by non-Jews. Certain parts must be removed by experts before the meat is sold. Particular abdominal fats, called chelev, are taken out through a process named nikkur. So is the sciatic nerve, the gid hanasheh. The reason for the nerve reaches back to Genesis 32:32, where the patriarch Jacob's was damaged when he fought with an angel. Some believe shechita ensures the animal dies instantly without unnecessary suffering. Many animal rights activists disagree, arguing the animal may not lose consciousness immediately, and have called for the practice to be banned.

• 4. Drawing Out The Blood

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  Salting is how the last of the blood leaves the meat. After an animal is slaughtered, the raw meat is traditionally cut, salted, and rinsed before any cooking begins. The salting uses coarse grain salt, commonly called kosher salt, which draws out the blood lodged on the meat's inner surface. The meat is then laid over a grating or colander to drain, and it stays there for the time it takes to walk one biblical mile, roughly 18 to 24 minutes. The salt residue is rinsed away with water, and only then can the meat be cooked. Meat that is roasted needs no prior salting, because fire causes a natural purging of blood. The liver, being very rich in blood, gets its own treatment and is grilled over an open flame. The correct size of the meat being salted has itself been a matter of rabbinic debate. The Turei Zahav, a 17th-century commentary on the Shulchan Arukh, ruled that the pieces can be very thick when salted. Yemenite Jewish practice instead follows Saadiah Gaon, who required that the meat be no larger than half a rotal, roughly 216 grams, so the salt's effects can penetrate fully. The same coarse salt that makes this possible explains a quirk of language. Kosher salt earns its name from koshering, the act of making something kosher, rather than from being certified itself.

• 5. Meat, Milk, And The Kitchen

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  "Cooking the kid in its mother's milk" is the phrase from the Torah that gave rise to one of the most visible kosher rules. From a broad interpretation of that commandment comes the law that meat and milk may never be mixed. They are not served at the same meal, cooked in the same utensils, or stored together. The Torah gives no reason, though it has been suggested that the original practice was seen as cruel and insensitive. Unlike other non-kosher foods, which may be sold to non-Jews, Jews are forbidden to benefit from meat-and-milk mixtures in any way. Observant Jews keep this separation physical. They maintain separate sets of dishes, and sometimes separate kitchens, for meat and dairy. The Yiddish terms fleishig and milchig, literally "meaty" and "milky," mark the two categories. After eating meat, a person waits anywhere from one to six hours before consuming milk products. The Shulchan Aruch recommends a six-hour gap, during which it is generally advised to abstain from brushing and rinsing the mouth. This dichotomy of the kitchen is so basic to observant life today that its absence in the historical record is striking. Shelomo Dov Goitein wrote that the split into meat and milk sections is never mentioned in the Geniza, and he believed early medieval Jewish families kept only one set of cutlery and cooking ware. According to David C. Kraemer, the practice of separate dishes developed only in the late 14th and 15th centuries. Before then, observant Jews may have waited overnight for absorbed gravy in a pot's walls to become insignificant before using it for the other food.

• 6. Categories And Hidden Lines

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  Pareve is the third path through a kosher kitchen, the neutral category that is neither meat nor dairy. It covers kosher fish, grains, produce, and other edible vegetation, and it includes eggs, which count as pareve despite being an animal product. Meat products, called b'sari or fleishig, contain kosher meat or poultry or derivatives such as animal gelatin. Dairy products, called milchig, contain milk or anything made from it. The lines between these categories are not only about ingredients. A non-dairy product processed on equipment used for milk must be treated as dairy, and the same logic applies to meat. Some processes can move a food from one category to another. Rennet, sometimes made from stomach linings, is still acceptable for making kosher cheese. Gelatin from kosher animals that were ritually slaughtered is pareve, and so are agar agar, carrageenan, and fish gelatin. Equipment can also be cleaned of its previous use. Dairy manufacturing equipment can be cleaned well enough that rabbis grant pareve status to what it produces. This creates an odd outcome on store shelves: some legitimately pareve products still carry "milk" warnings, because someone with a strong allergic sensitivity might react to dairy residue. Produce seems simple, since anything that grows from the earth is permissible, but vegetables hide a complication of their own. Spinach and cauliflower must be checked for insect infestation, and the proper procedure varies by species and by the views of individual rabbis. Even hydroponic produce raises new kosher questions, especially in determining the correct blessing to say before eating.

• 7. The Land And The Calendar

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  Produce grown in the Land of Israel carries obligations that produce elsewhere does not. A modified version of the biblical tithes must be applied, including Terumat HaMaaser, Maaser Rishon, Maaser Sheni, and Maasar Ani; untithed produce is called tevel and is forbidden. The fruit of a tree's first three years is forbidden as orlah, a rule drawn from Leviticus 19:23 that applies in both the Land of Israel and the diaspora, and it extends to grapes and the wine made from them. Crops grown in the seventh year take on a special holiness and, unless managed carefully, are forbidden as a violation of the Shmita, the Sabbatical Year. Some of these laws hinge on geography and the calendar in ways that remain contested. New grain, called chadash, is biblically prohibited until the second day of Passover, but many hold the rule does not apply outside the Land of Israel. The calendar tightens further during Passover itself. The most important Passover rule is the ban on leavened bread and its derivatives, known as chametz, derived from Exodus 12:15. Utensils used for chametz are forbidden during the festival unless they have been ritually cleansed, and observant Jews often keep separate meat and dairy sets used only for Passover. Some groups go beyond kashrut entirely, avoiding kitniyot, gebrochts, or garlic. The reach of these calendar rules even touches tobacco, which can receive a year-long kosher-for-Passover certification guaranteeing it never contacted forbidden chametz grains.

• 8. The Mark On The Box

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  A hechsher is the proprietary symbol that tells a shopper a product complies with kosher law. Over the past century, certification agencies have multiplied, inspecting products, manufacturers, and restaurants, with a rabbi or committee visiting facilities to examine methods and ingredients. The symbols are too numerous to list. One of the most common in the United States belongs to the Union of Orthodox Congregations, a U inside a circle known as O-U. In Britain, the London Beth Din uses a KLBD logo and the Manchester Beth Din an MK. A single letter K alone only indicates the company's own claim, since many countries do not allow letters to be trademarked. Letters added to a symbol signal the category: D for dairy, DE for dairy equipment, M for meat, and P for Passover, which is never used for pareve. This marketing story has clear milestones. The uniqueness of kosher food was advertised as early as 1849. In 1911, Procter & Gamble became the first company to advertise a product, Crisco, as kosher. Over the next two decades, names such as Lender's Bagels, Maxwell House, Manischewitz, and Empire claimed shelf space. In the 1960s, Hebrew National hotdogs ran a "we answer to a higher authority" campaign aimed at Jews and non-Jews alike, and kosher became a symbol of both quality and value. Menachem Lubinsky, founder of the Kosherfest trade fair, estimates as many as 14 million kosher consumers and 40 billion dollars in U.S. sales of kosher products. The economics help explain the labels. In 1975, a major national newspaper estimated certification cost at 6.5 millionths of a cent per item for a frozen-food product. A 2005 report found most U.S. certifying agencies are non-profit, with on-site supervisors typically earning less per visit than an auto mechanic does per hour. The Orthodox Union claims a kosher product placed next to a non-kosher competitor will do better by 20 percent. The audience reaches well past observant Jews, drawing in Muslims who keep halal, Seventh-day Adventists, vegetarians, vegans, and the lactose-intolerant, the last of whom can rely on a trustworthy pareve mark.

  "Legitimate," "acceptable," "genuine": in colloquial English, kosher has slipped far from the kitchen. In Ancient Hebrew the word meant advantageous, proper, suitable, or to succeed, and the Babylonian Talmud once used it in the sense of "virtuous," calling Darius I a "kosher king." Darius, the Persian ruler who reigned from 522 to 486 BCE, fostered the building of the Second Temple. The word's reach extends to a kosher dill pickle, which simply means a pickle made the traditional way of Jewish New York City pickle-makers, heavy with garlic in the brine, and not necessarily compliant with the food laws at all. The word even crossed an ocean and changed meaning. In Suriname, a treef, derived through Sranan Tongo from Hebrew, is a food taboo, carried there by Sephardi Jews who arrived in the 17th century. Among people of African descent, eating a forbidden food is believed to cause major diseases, particularly leprosy. A treef is inherited from the father's side but can be revealed in a dream, often by a woman, and if a child who keeps his father's treef still develops a skin condition, it is taken as a strong sign the child was fathered by another man. The same Hebrew root gave Sranan the word kaseri, meaning ritually clean. Not every modern use involves eating at all. Some Orthodox retailers sell kosher cell phones, stripped-down devices with limited features. The newest debates push the laws into territory the Torah never imagined. The first genetically modified animal approved by the FDA for human consumption, the AquAdvantage salmon, carries a gene from a non-kosher organism, even though salmon is normally kosher. Some argue the intermixing of species violates the Talmud, while others invoke the one-in-sixty law, noting the foreign gene accounts for less than 1/60 of the animal, and conclude the salmon is kosher after all.