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Kashrut (also kashruth or kashrus, כַּשְׁרוּת) is the set of Jewish religious dietary laws. Food that may be consumed according to halakha (Jewish law) is termed kosher in English, from the Ashkenazi pronunciation of the Hebrew term kashér (כָּשֵׁר), meaning "fit" (in this context, fit for consumption).
Among the numerous laws that form part of kashrut are the prohibitions on the consumption of unclean animals (such as pork, shellfish (both Mollusca and Crustacea) and most insects, with the exception of certain species of kosher locusts), mixtures of meat and milk, and the commandment to slaughter mammals and birds according to a process known as shechita. There are also laws regarding agricultural produce that might impact on the suitability of food for consumption.
Most of the basic laws of kashrut are derived from the Torah's Books of Leviticus and Deuteronomy. Their details and practical application, however, are set down in the oral law (eventually codified in the Mishnah and Talmud) and elaborated on in the later rabbinical literature. While the Torah does not state the rationale for most kashrut laws, many reasons have been suggested, including philosophical, practical and hygienic.
Over the past century, there have developed numerous rabbinical organizations that certify products, manufacturers, and restaurants as kosher, usually using a symbol (called a hechsher) to indicate their support. Presently, about a sixth of American Jews or 0.3% of the American population fully keep kosher, and many more abstain from some non-kosher foods, especially pork.
- Philosophical explanations 1.1
- Health explanations 1.2
Prohibited foods 2
- Permitted and forbidden animals 2.1
- Separation of meat and milk 2.2
- Kosher slaughter 2.3
- Kosher utensils 2.4
- Passover laws 2.5
- Produce of the Land of Israel 2.6
- Vegetables 2.7
- Pareve foods 2.8
Supervision and marketing 3
- Hashgacha 3.1
- Product labeling standards 3.2
- History of kosher supervision and marketing 3.3
- Legal usage 3.4
- Costs 3.5
Society and culture 4
- Adherence 4.1
- Linguistics 4.2
- See also 5
- References 6
- Further reading 7
- External links 8
Jewish philosophy divides the 613 mitzvot into three groups—laws that have a rational explanation and would probably be enacted by most orderly societies (mishpatim), laws that are understood after being explained but would not be legislated without the Torah's command (edot), and laws that do not have a rational explanation (chukim). Some Jewish scholars say that kashrut should be categorized as laws for which there is no particular explanation, since the human mind is not always capable of understanding divine intentions. In this line of thinking, the dietary laws were given as a demonstration of God's authority, and man must obey without asking why. However, Maimonides believed that Jews were permitted to seek out reasons for the laws of the Torah.
Some theologians have said that the laws of kashrut are symbolic in character: Kosher animals represent virtues, while non-kosher animals represent vices. The 1st century BCE Letter of Aristeas argues that the laws "have been given ... to awake pious thoughts and to form the character". This view reappears in the work of the 19th century Rabbi Samson Raphael Hirsch.
The Torah prohibits "seething the kid (goat, sheep, calf) in its mother's milk". While the Bible does not provide a reason, it has been suggested that the practice was perceived as cruel and insensitive.
Hasidism believes that everyday life is imbued with channels connecting with Divinity, the activation of which it sees as helping the Divine Presence to be drawn into the physical world; Hasidism argues that the food laws are related to the way such channels, termed sparks of holiness, interact with various animals. These sparks of Holiness are released whenever a Jew manipulates any object for a holy reason (which includes eating); however, not all animal products are capable of releasing their sparks of holiness. The Hasidic argument is that animals are imbued with signs that reveal the release of these sparks, and the signs are expressed in the biblical categorization of ritually clean and ritually unclean.
According to Christian theologian Gordon J. Wenham, the purpose of kashrut was to help Jews maintain a distinct and separate existence from other peoples; he says that the effect of the laws was to prevent socialization and intermarriage with non-Jews, preventing Jewish identity from being diluted. Wenham argued that since the impact of the food laws was a public affair, this would have enhanced Jewish attachment to them as a reminder of their distinct status as Jews.
There have been attempts to provide empirical support for the view that Jewish food laws have an overarching health benefit or purpose, one of the earliest being from Maimonides in his Guide for the Perplexed. In 1953, David Macht, an Orthodox Jew and proponent of the theory of biblical scientific foresight, conducted toxicity experiments on many kinds of animals and fish. His experiment involved lupin seedlings being supplied with extracts from the meat of various animals; Macht reported that in 100% of cases, extracts from ritually unclean meat inhibited the seedling's growth more than that from ritually clean meats. At the same time, these explanations are controversial. Scholar Lester L. Grabbe, writing in the Oxford Bible Commentary on Leviticus, states that "[a]n explanation now almost universally rejected is that the laws in this section [Leviticus 11-15] have hygiene as their basis. Although some of the laws of ritual purity roughly correspond to modern ideas of physical cleanliness, many of them have little to do with hygiene. For example, there is no evidence that the 'unclean' animals are intrinsically bad to eat or to be avoided in a Mediterranean climate, as is sometimes asserted."
The laws of kashrut can be classified according to the origin of the prohibition (Biblical or rabbinical) and whether the prohibition concerns the food itself or a mixture of foods.
Biblically prohibited foods include:
- Non-kosher animals and birds (based on Leviticus 11:3–8 and Deuteronomy 14:3–21): mammals require certain identifying characteristics (cloven hooves and being ruminants), while birds require a tradition that they can be consumed. Fish require scales and fins (thus excluding catfish, for instance). All invertebrates are non-kosher apart from certain types of locust, on which most communities lack a clear tradition. No reptiles or amphibians are kosher.
- Carrion (nevelah): meat from a kosher animal that has not been slaughtered according to the laws of shechita.
- Injured (terefah): an animal with a significant defect or injury, such as a fractured bone or particular types of lung adhesions.
- Blood (dam): blood of kosher mammals and fowl is removed through salting, with special procedures for the liver, which is very rich in blood.
- Particular fats (chelev): particular parts of the abdominal fat of cattle, goats and sheep must be removed by a process called nikkur.
- The twisted nerve (gid hanasheh): the sciatic nerve, as according to Genesis 32:32 the patriarch Jacob's was damaged when he fought with an angel, cannot be eaten and is removed by nikkur.
- Limb of a living animal (ever min ha-chai): in Genesis 9:4, God forbade Noah and his descendants to consume a limb torn from a live animal. Hence, Jewish law considers this prohibition applicable even to non-Jews, and therefore, a Jew may not give or sell such meat to a non-Jew.
- Untithed food (tevel): produce of the Land of Israel requires the removal of certain tithes, which in ancient times were given to the Kohanim (priests), Levites and the poor (terumah, maaser rishon and maaser ani respectively) or taken to the Old City of Jerusalem to be eaten there (maaser sheni).
- Fruit during the first three years (orlah): according to Leviticus 19:23, fruit from a tree in the first three years after planting cannot be consumed (both in the Land of Israel and the diaspora). This applies also to the fruit of the vine - grapes, and wine produced from them.
- New grain (chadash): in Leviticus 23:14 the Bible prohibits newly grown grain (planted after Passover the previous year) until the second day of Passover; there is debate as to whether this law applies to grain grown outside the Land of Israel.
- Wine of libation (yayin nesekh): wine that may have been dedicated to idolatrous practices.
Biblically prohibited mixtures include:
- Mixtures of meat and milk (basar be-chalav): this law derives from the broad interpretation of the commandment not to "cook a kid in its mother's milk" (Exodus 23:19, Exodus 34:26, and Deuteronomy 14:21); other non-kosher food may be used for other benefit (e.g. sold to non-Jews), but mixtures of meat and milk are prohibited even with regards to other benefit.
- Plants grown together (kilayim): in the Land of Israel plants are to be grown separately and not in close proximity according to Leviticus 19:19 and Deuteronomy 22:9-11. A specific subdivision of this law is kil'ei ha-kerem, the prohibition of planting any grain of vegetable near a grapevine; this law applies to Jews throughout the world, and one may not derive benefit from the produce.
Rabbinically prohibited foods include:
- Non-Jewish milk (chalav akum): milk that may have an admixture of milk from non-kosher animals (see below for current views on this prohibition).
- Non-Jewish cheese (gevinat akum): cheese that may have been produced with non-kosher rennet.
- Non-Jewish wine (stam yeinam): wine that while not produced for idolatrous purposes may otherwise have been poured for such a purpose or alternatively when consumed will lead to intermarriage.
- Food cooked by a non-Jew (bishul akum): this law was enacted for concerns of intermarriage.
- Non-Jewish bread (pat akum): this law was enacted for concerns of intermarriage.
- Health risk (sakanah): certain foods and mixtures are considered a health risk, such as mixtures of fish and meat.
Permitted and forbidden animals
Only meat from particular species is permissible. Mammals that both chew their cud (ruminate) and have cloven hooves can be kosher. Animals with one characteristic but not the other (the camel, the hyrax, and the hare because they have no cloven hooves, and the pig because it does not ruminate) are specifically excluded (Leviticus 11:3–8). In 2008, a rabbinical ruling determined that giraffes and their milk are eligible to be considered kosher. The giraffe has both split hooves and chews its cud, characteristics of animals considered kosher. Findings from 2008 show that giraffe milk curdles, meeting kosher standards. Although kosher, the giraffe is not slaughtered today because the process would be very costly. Giraffes are difficult to restrain, and their use for food could cause the species to become endangered.
Non-kosher birds are listed outright (Deuteronomy 14:12–18) but the exact zoological references are disputed and some references refer to families of birds (24 are mentioned). The Mishnah refers to four signs provided by the sages. First, a dores (predatory bird) is not kosher. Additionally, kosher birds possess three physical characteristics: an extra toe in the back (which does not join the other toes in supporting the leg), a zefek (crop), and a korkoban (gizzard) with a peelable lumen. However, individual Jews are barred from merely applying these regulations alone; an established tradition (masorah) is necessary to allow birds to be consumed, even if it can be substantiated that they meet all four criteria. The only exception to this is turkey. There was a time when certain authorities considered the signs enough, so Jews started eating this bird without a masorah because it possesses all the signs (simanim in Hebrew).
Fish must have fins and scales to be kosher (Leviticus 11:9–12). Shellfish and other non-fish water fauna are not kosher. Here is a list of kosher species of fish. Insects are not kosher except for certain species of kosher locust. Generally any animal that eats other animals, whether they kill their food or eat carrion (Leviticus 11:13–31), is not kosher, as well as any animal that was partially eaten by other animals (Exodus 22:30-31).
|Mammals||Carnivores; animals that do not chew the cud (e.g. the pig); animals that do not have cloven hooves (e.g., the camel, the hyrax, the hare)|
|Birds||Birds of prey; scavengers|
|Reptiles and amphibians||All|
|Water animals||Those that do not have both fins and scales|
|Insects||All, except a particular type of locust that, according to most, cannot be identified today|
Separation of meat and milk
Meat and milk (or derivatives) cannot be mixed (Deuteronomy 14:21) in the sense that meat and dairy products are not served at the same meal, served or cooked in the same utensils, or stored together. Observant Jews have separate sets of dishes, and sometimes different kitchens, for meat and milk, and wait anywhere between one and six hours after eating meat before consuming milk products. The milchig and fleishig utensils and dishes are the commonly referred to Yiddish delineations between dairy and meat (lit. milky and meaty) utensils and dishes respectively.
Mammals and fowl must be slaughtered by a trained individual (a shochet) using a special method of slaughter, shechita (Deuteronomy 12:21). Among other features, shechita slaughter severs the jugular vein, carotid artery, esophagus, and trachea in a single continuous cutting movement with an unserrated, sharp knife. Failure of any of these criteria renders the meat of the animal unsuitable. The body must be checked after slaughter to confirm that the animal had no medical condition or defect that would have caused it to die of its own accord within a year, which would make the meat unsuitable. These conditions (treifot) include 70 different categories of injuries, diseases, and abnormalities whose presence renders the animal non-kosher. It is forbidden to consume certain parts of the animal, such as certain fats (chelev) and the sciatic nerves from the legs. As much blood as possible must be removed (Leviticus 17:10) through the kashering process; this is usually done through soaking and salting the meat, but the liver, as it is rich in blood, is grilled over an open flame. Fish (and kosher locusts, for those follow the traditions permitting them) must be killed before being eaten, but no particular method has been specified in Jewish law.
Utensils used for non-kosher foods become non-kosher, and make even otherwise kosher food prepared with them non-kosher. Some such utensils, depending on the material they are made from, can be made suitable for preparing kosher food again by immersion in boiling water or by the application of a blowtorch. Food prepared in a manner that violates the Shabbat (Sabbath) may not be eaten; although in certain instances it is permitted after the Shabbat is over.
Passover has special dietary rules, the most important of which is the prohibition on eating leavened bread or derivatives of this, which are known as chametz. This prohibition is derived from Exodus 12:15. Utensils used in preparing and serving chametz are also forbidden on Passover unless they have been ritually cleansed (kashered). Observant Jews often keep separate sets of meat and dairy utensils for Passover use only. In addition, some groups follow various eating restrictions on Passover that go beyond the rules of kashrut, such as not eating gebrochts or garlic.
Produce of the Land of Israel
Biblical rules also control the use of agriculture produce. For produce grown in the Land of Israel a modified version of the biblical tithes must be applied, including Terumat HaMaaser, Maaser Rishon, Maaser Sheni, and Maaser Ani (untithed produce is called tevel); the fruit of the first three years of a tree's growth or replanting are forbidden for eating or any other use as orlah; produce grown in the Land of Israel on the seventh year obtains k'dushat shvi'it, and unless managed carefully is forbidden as a violation of the Shmita (Sabbatical Year). Some rules of kashrut are subject to different rabbinical opinions. For example, many hold that the rule against eating chadash (new grain) before the 16th of the month Nisan does not apply outside the Land of Israel.
Many vegetarian restaurants and producers of vegetarian foods acquire a bishul Yisrael. Vegetables such as spinach and cauliflower must be checked for insect infestation. The proper procedure for inspecting and cleaning varies by species, growing conditions, and views of individual rabbis.
Some processes convert a meat or dairy product into a pareve (neither meat nor dairy) one. For example, rennet is sometimes made from stomach linings, yet is acceptable for making kosher cheese, but such cheeses might not be acceptable to some vegetarians, who would eat only cheese made from a vegetarian rennet. The same applies to kosher gelatin, an animal product, derived from kosher animal sources. Other gelatin-like products from non-animal sources such as agar agar and carrageenan are pareve by nature. Fish gelatin is derived from fish and is therefore (like all kosher fish products) pareve. Eggs are also considered pareve despite being an animal product.
Kashrut has procedures by which equipment can be cleaned of its previous non-kosher use, but that might be inadequate for those with allergies, vegetarians, or adherents to other religious statutes. For example, dairy manufacturing equipment can be cleaned well enough that the rabbis grant pareve status to products manufactured with it. Nevertheless, someone with a strong allergic sensitivity to dairy products might still react to the dairy residue, and that is why some products that are legitimately pareve carry "milk" warnings.
Supervision and marketing
Certain foods must be prepared in whole or in part by Jews. This includes grape wine, certain cooked foods (bishul akum), cheese (g'vinat akum), and according to some also butter (chem'at akum); dairy products (Hebrew: חלב ישראל chalav Yisrael "milk of Israel"); and bread (Pas Yisroel).
Product labeling standards
Although reading the label of food products can identify obviously non-kosher ingredients, some countries allow manufacturers to omit identification of certain ingredients. Such "hidden" ingredients may include lubricants and flavorings, among other additives; in some cases, for instance, the use of natural flavorings, these ingredients are more likely to be derived from non-kosher substances. Furthermore, certain products, such as fish, have a high rate of mislabeling, which may result in a non-kosher fish being sold in a package labeled as a species of kosher fish.
Producers of foods and food additives can contact Jewish religious authorities to have their products certified as kosher: this involves a visit to the manufacturing facilities by an individual rabbi or a committee from a rabbinic organization, who will inspect the production methods and contents, and if everything is sufficiently kosher a certificate would be issued.
Manufacturers sometimes identify the products that have received such certification by adding particular graphical symbols to the label. These symbols are known in Judaism as Union of Orthodox Congregations, who use a U inside a circle, symbolising the initials of Orthodox Union. A single K is sometimes used as a symbol for kosher, but since many countries do not allow letters to be trademarked (the method by which other symbols are protected from misuse), it only indicates that the company producing the product claims that it is kosher.
Many of the certification symbols are accompanied by additional letters or words to indicate the category of the product, according to Jewish law; the categorisation may conflict with legal classifications, especially in the case of food that Jewish law regards as dairy, but legal classification does not.
- DE—Dairy equipment
- M—Meat, including poultry
- Pareve—Food that is neither meat nor dairy
- P—Passover-related (P is not used for Pareve)
In many cases constant supervision is required because, for various reasons, such as changes in manufacturing processes, products that once were kosher may cease to be so. For example, a kosher lubricating oil may be replaced by one containing grapevine among the Jewish community discusses which products are now questionable, as well as products which have become kosher but whose labels have yet to carry the hechsher. Some newspapers and periodicals also discuss kashrut products.
Products labeled kosher-style are non-kosher products that have characteristics of kosher foods, such as all-beef hot dogs, or are flavored or prepared in a manner consistent with Ashkenazi practices, like dill pickles. The designation usually refers to delicatessen items.
History of kosher supervision and marketing
In 1911 Procter & Gamble became the first company to advertise one of their products, Crisco, as kosher. Over the next two decades, companies such as Lender's Bagels, Maxwell House, Manischewitz, and Empire evolved and gave the kosher market more shelf-space. In the 1960s, Hebrew National hotdogs launched a "we answer to a higher authority" campaign to appeal to Jews and non-Jews alike. From that point on, "kosher" became a symbol for both quality and value. The kosher market quickly expanded, and with it more opportunities for kosher products. Menachem Lubinsky, founder of the Kosherfest trade fair, estimates as many as 14 million kosher consumers and $40 billion in sales of kosher products in the USA.
In 2014 the Israeli Defense Forces decided to allow female kosher supervisors to work in its kitchens on military bases, and the first women kosher inspectors were certified in Israel.
Advertising standards laws in many jurisdictions prohibit the use of the phrase kosher in a product's labelling unless the producer can show that the product conforms to Jewish dietary laws; however, different jurisdictions often define the legal qualifications for conforming to Jewish dietary laws differently. For example, in some places the law may require that a rabbi certify the kashrut nature, in others the rules of kosher are fully defined in law, and in others still it is sufficient that the manufacturer only believes that the product complies with Jewish dietary regulations. In several cases, laws restricting the use of the term kosher have later been determined to be illegal religious interference.
The cost of certification for mass-produced items is typically minuscule, and is usually more than offset by the advantages of being certified. In 1975 the cost per item for obtaining kosher certification was estimated by 
In some European communities there is a special tax imposed on the purchase of kosher meat to help support the community’s educational institutions. In 2009, delegates at a meeting of the Rabbinical Council of Europe were in broad agreement that the tax which supports the rabbinate, mikvo’os and other communal facilities should be reduced. "While the supermarket Tesco sells a whole chicken for £2, its kosher counterpart of similar weight costs five to six times more."
Society and culture
About one-sixth of American Jews maintain the kosher diet. Many Jews observe kashrut partially, by abstaining from pork or shellfish, or not drinking milk with a meat dish. Some keep kosher at home but will eat in a non-kosher restaurant. In 2012, one analysis of the specialty food market in North America estimated that only 15% of Kosher consumers were Jewish. A sizable non-Jewish segment of the population views kosher certification as an indication of wholesomeness. Muslims, Hindus, and people with allergies to dairy foods, often consider the kosher-pareve designation as an assurance that a food contains no animal-derived ingredients, including milk and all of its derivatives. However, since kosher-pareve foods may contain honey, eggs, or fish, strict vegetarians cannot rely on the certification.
Kosher (Hebrew: כשר) in Ancient Hebrew means be advantageous, proper, suitable, or succeed  according to the Brown-Driver-Briggs Hebrew and English Lexicon. In Modern Hebrew, it generally refers to kashrut but can also sometimes mean "proper". For example, the Babylonian Talmud uses kosher in the sense of virtuous, when referring to Darius I as a "kosher king"; Darius, a Persian King, assisted in building the Second Temple. In English, kosher often means legitimate, acceptable, permissible, genuine, or authentic.
The word kosher is also part of some common product names. Sometimes it is used as an abbreviation of koshering, meaning the process for making something kosher; for example, kosher salt is a form of salt with irregularly shaped crystals, making it particularly suitable for preparing meat according to the rules of kashrut, because the increased surface area of the crystals absorbs blood more effectively. At other times it is used as a synonym for Jewish tradition; for example, a kosher dill pickle is simply a pickle made in the traditional manner of Jewish New York City pickle makers, using a generous addition of garlic to the brine, and is not necessarily compliant with the traditional Jewish food laws.
- Comparison of Islamic and Jewish dietary laws
- Christian dietary laws
- Jewish cuisine
- Kosher foods
- Kosher tax
- Sabbath food preparation
- Halal, Islamic dietary laws
- Unclean animal
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