Kashrut

Kashrut (also kashruth or kashrus, ) is a set of dietary laws dealing with the foods that Jews are permitted to eat and how those foods must be prepared according to Jewish law. Food that may be consumed is deemed kosher ( in English, ), from the Ashkenazi pronunciation of the Hebrew term "kashér" (), meaning "fit" (in this context: "fit for consumption").
Although the details of the laws of "kashrut" are numerous and complex, they rest on a few basic principles:
Every food that is considered kosher is also categorized as follows:
While any produce that grows from the earth, such as fruits, grains, vegetables and mushrooms, are always permissible, laws regarding the status of certain agricultural produce, especially that grown in the Land of Israel, such as tithes and produce of the Sabbatical year, impact their permissibility 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 Torah (eventually codified in the Mishnah and Talmud) and elaborated on in the later rabbinical literature. Although the Torah does not state the rationale for most "kashrut" laws, some suggest that they are only tests of obedience, while others have suggested philosophical, practical and hygienic reasons.
Over the past century, many kashrut certification agencies have started to certify products, manufacturers, and restaurants as kosher, usually authorizing the use of a proprietary symbol or certificate, called a "hechsher", to be displayed by the food establishment or on the product, which indicates that they are in compliance with the kosher laws. This labeling is useful for many people, including for those within religions that expect adherence a similar set of dietary laws, people with allergies to dairy foods, or vegans, who use the various kosher designations to determine whether a food has meat or dairy-derived ingredients or similar.
Explanations.
Philosophical.
Jewish philosophy divides the 613 commandments (or "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 ("eidot"), 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.
Hasidic Judaism 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.
Medical.
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 is that of Maimonides in "The 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, says "[a]n explanation now almost universally rejected is that the laws in this section 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."
Laws of Kashrut.
Prohibited foods.
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:
Biblically prohibited mixtures include:
Rabbinically prohibited foods include:
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. 
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 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 the turkey. There was a time when certain authorities considered the signs sufficient, 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. Shellfish and other non-fish water fauna are not kosher. (See 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, is not kosher, as well as any animal that has been partially eaten by other animals.
Separation of meat and milk.
Meat and milk (or derivatives) may not be mixed 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" (lit. "milky" and "meaty") utensils and dishes are the commonly referred-to Yiddish delineations between dairy and meat ones, respectively. 
Shelomo Dov Goitein writes, "the dichotomy of the kitchen into a meat and a milk section, so basic in an observant Jewish household, is … never mentioned in the Geniza." Goitein believed that in the early Middle Ages Jewish families kept only one set of cutlery and cooking ware. According to David C. Kraemer the practice of keeping separate sets of dishes developed only in the late 14th and 15th centuries. It's possible observant Jews before then waited overnight for the meat or dairy gravy absorbed in a pot’s walls to become insignificant ("") before using the pot for the other foodstuff (meat or dairy).
Kosher slaughter.
Mammals and fowl must be slaughtered by a trained individual (a "shochet") using a special method of slaughter, "shechita". "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 non-kosher.
The body of the slaughtered animal 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, the process of excision being done by experts before the meat is sold. 
As much blood as possible must be removed 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 who follow the traditions permitting them) must be killed before being eaten, but no particular method has been specified in Jewish law. Legal aspects of ritual slaughter are governed not only by Jewish law but civil law as well.
Some believe that this ensures the animal dies instantly without unnecessary suffering, but many animal-rights activists view the process as cruel, claiming that the animal may not lose consciousness immediately, and activists have called for it to be banned. Animal science researcher, Temple Grandin stated that kosher slaughter, no matter how well its done, is not instantaneous, whereas stunning properly with a captive bolt is instantaneous. She gives various times for loss of consciousness via kosher ritual slaughter, ranging from 15 to 90 seconds depending on measurement type and individual kosher slaugtherhouse.
Preparation of meats.
When an animal is ritually slaughtered ("shechted") the raw meat is traditionally cut, rinsed and salted, prior to cooking. Salting of raw meat draws out the blood that lodges on the inner surface of the meat. The salting is done with coarse grain salt, commonly referred to as kosher salt, after which the meat is laid over a grating or colander to allow for drainage, remaining so for the duration of time that it takes to walk one biblical mile (approx. 18–24 minutes). Afterwards, the residue of salt is rinsed away with water, and the meat cooked. 
Meat that is roasted requires no prior salting, as fire causes a natural purging of blood.
"Turei Zahav" ("Taz"), a 17th-century commentary on the Shulchan Arukh, ruled that the pieces of meat can be "very thick" when salting. The Yemenite Jewish practice, however, follows Saadiah Gaon, who required that the meat not be larger than half a "rotal" (i.e. ca. 216 grams) when salting. This allows the effects of the salt to penetrate. 
Some Orthodox Jewish communities require the additional stricture of submersing raw meat in boiling water prior to cooking it, a practice known as "ḥaliṭah" (), “blanching.” This was believed to constrict the blood lodged within the meat, to prevent it from oozing out when the meat was eaten. The raw meat is left in the pot of boiling water for as long as it takes for the meat to whiten on its outer layer. 
If someone wanted to use the water for soup after making "ḥaliṭah" in the same pot, he could simply scoop out the film, froth and scum that surface in the boiling water. 
"Ḥaliṭah" is not required when roasting meat over a fire, as the fire constricts the blood.
Kosher utensils.
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 laws.
Passover has stricter 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 "kitniyot", "gebrochts" or garlic.
Produce of the Land of Israel.
Biblical rules also control the use of agriculture produce, for example, with respect to their tithing, or when it is permitted to eat them or to harvest them, and what must be done to make them suitable for human consumption. 
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 "Maasar 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.
Vegetables.
Many vegetarian restaurants and producers of vegetarian foods acquire a "hechsher", certifying that a rabbinical organization has approved their products as being kosher. 
The "hechsher" usually certifies that certain vegetables have been checked for insect infestation and steps have been taken to ensure that cooked food meets the requirements of "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.
Pareve foods.
A "pareve" food is one which is neither meat nor dairy. Fish fall into this category, as well as any food that is not animal-derived. Eggs are also considered "pareve" despite being an animal product.
Some processes convert a meat- or dairy-derived product into a "pareve" one. For example, rennet is sometimes made from stomach linings, yet is acceptable for making kosher cheese. Gelatins derived from kosher animal sources (which were ritually slaughtered) are also "pareve". Other gelatin-like products from non-animal sources such as agar agar and carrageenan are "pareve" by nature. Fish gelatin, like all kosher fish products, is "pareve".
Jewish law generally requires that bread be kept "parve" (i.e., not kneaded with meat or dairy products nor made on meat or dairy equipment).
"Kashrut" has procedures by which equipment can be cleaned of its previous non-kosher or meat/dairy use, but those may be inadequate for vegetarians, those with allergies, or adherents to other religious laws. 
For example, dairy manufacturing equipment can be cleaned well enough that the rabbis grant "pareve" status to products manufactured with it but someone with a strong allergic sensitivity to dairy products might still react to the dairy residue. That is why some products that are legitimately "pareve" carry "milk" warnings.
Cannabis.
If smoked, under normal circumstances there is no reason cannabis (marijuana) would not be kosher, although some rabbis apply this only to medical cannabis, not recreational usage. 
However, this is excepting that smoking it typically involves lighting a spark, so it would not be appropriate for example after sundown on Shabbat. If cannabis is "eaten", as cannabis edibles are, on the other hand, the issue is not as clear cut, as there may be small insects inside which are not kosher. 
For cannabis grown in Israel, the plants must observe "shmittah", but this does not apply to cannabis from elsewhere. At least one brand of cannabis edibles is certified to follow the laws of "kashrut".
Tobacco.
Although it is not a food product, some tobacco receives a year-long kosher certification. This year-long certification means that the tobacco is certified also for Passover where different restrictions may be in place. Tobacco may, for example, come into contact with some "chametz" grains that are strictly forbidden during Passover and the certification is a guarantee that it is free from this type of contamination. 
In Israel this certification is given by a private "kashrut" rabbinic group Beit Yosef, but the Chief Rabbinate has objected to granting of any certification by rabbis because of health risks from tobacco.
Genetically modified foods.
With the advent of genetic engineering, a whole new type of food has been brought into the world, and scholars in both academia and Judaic faith have differing viewpoints on whether these new strains of foods are to be considered kosher or not. The first genetically modified animal approved by the FDA for human consumption is the AquAdvantage salmon and, while salmon is normally an acceptably kosher food, this modified organism has a gene from a non-kosher organism.
In 2015, the Committee on Jewish Law and Standards of the Rabbinical Assembly released a document regarding genetically modified organisms, stating that modification of gene sequences via the introduction of foreign DNA in order to convey a specific capability in the new organism is allowable, that entirely new species should not be intentionally created, and that the health implications of genetically modified foods must be considered on an individual basis.
Some put forth that this intermixing of species is against the teachings of the Talmud and thus against Jewish Law and non-kosher. Others argue that the one in sixty parts law of "kashrut" is of significance, and that the foreign gene accounts for less than 1/60 of the animal and thus the modified salmon is kosher.
Supervision and marketing.
"Hashgacha".
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 "hechsherim". Due to differences in "kashrut" standards held by different organizations, the "hechsheirim" of certain Jewish authorities may at times be considered invalid by other Jewish authorities. The certification marks of the various rabbis and organisations are too numerous to list, but one of the most commonly used in the United States of America is that of the Union of Orthodox Congregations, who use a "U" inside a circle ("O-U"), symbolising the initials of "Orthodox Union". In Britain, commonly used symbols are the "KLBD" logo of the London Beth Din and the "MK" logo of the Manchester Beth Din. 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 categorization may conflict with legal classifications, especially in the case of food that Jewish law regards as "dairy", but legal classification does not.
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 tallow, which many rabbinic authorities view as non-kosher. Such changes are often coordinated with the supervising rabbi or supervising organization to ensure that new packaging does not suggest any "hechsher" or "kashrut". In some cases, however, existing stocks of pre-printed labels with the "hechsher" may continue to be used on the now non-kosher product. An active 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.
Food producers often look to expand their markets or marketing potential, and offering kosher food has become a way to do that. The uniqueness of kosher food was advertised as early as 1849. 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 kosher consumers and in sales of kosher products in the U.S.A.
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.
Legal usage.
Advertising standards laws in many jurisdictions prohibit the use of the phrase "kosher" in a product's labeling 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.
Costs.
In the United States, 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 New York Times" estimated the cost per item for obtaining kosher certification at 6.5 millionths of a cent ($0.000000065) per item for a General Foods frozen-food item. According to a 2005 report by Burns & McDonnell, most U.S. national certifying agencies are non-profit, only charging for supervision and on-site work, for which the on-site supervisor "typically makes less per visit than an auto mechanic does per hour". However, re-engineering an existing manufacturing process can be costly. Certification usually leads to increased revenues by opening up additional markets to Jews who keep kosher, Muslims who keep halal, Seventh-day Adventists who keep the main laws of Kosher Diet, vegetarians, and the lactose-intolerant who wish to avoid dairy products (products that are reliably certified as "pareve" meet this criterion). According to the Orthodox Union, one of the largest "kashrut" organizations in the United States, "when positioned next to a competing non-kosher brand, a kosher product will do better by 20%".
In some European Jewish communities, kosher supervision of meat includes a "tax" used to fund Jewish education in the community, which makes kosher meat more expensive than the cost of supervision alone would imply.
Society and culture.
Adherence.
Many Jews partially observe "kashrut," by abstaining from pork or shellfish or by not drinking milk with meat dishes. Some keep kosher at home but eat in non-kosher restaurants. In 2012, one analysis of the specialty food market in North America estimated that only 15% of kosher consumers were Jewish. Kosher meat is regularly consumed by Muslims when "halal" is not available. 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, vegans cannot rely on the certification.
About a sixth of American Jews or 0.3% of the American population fully keep kosher, and many more of them do not strictly follow all of the rules but still abstain from some prohibited foods (especially pork). The Seventh-day Adventist Church, a Christian denomination, preaches a health message which expects adherence to the kosher dietary laws.
A 2013 survey found that 22% of American Jews claimed to keep kosher in their homes.
Linguistics.
In Ancient Hebrew the word "kosher" () 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 it 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 (reigned 522–486 BCE), fostered the building of the Second Temple. In colloquial English, "kosher" often means "legitimate", "acceptable", "permissible", "genuine", or "authentic".
The word "kosher" can form 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 "kosher" can occur 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.
Other uses.
Although the term "kosher" relates mainly to food, it sometimes occurs in other contexts. Some Orthodox retailers sell kosher cell-phones - stripped-down devices with limited features.