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Chametz (also chometz, ḥametz, ḥameṣ, ḥameç and other spellings transliterated from Hebrew: חָמֵץ / חמץ; IPA: [χaˈmets]) are foods with leavening agents that are forbidden on the Jewish holiday of Passover. According to halakha, Jews may not own, eat or benefit from chametz during Passover. This law appears several times in the Torah; the punishment for eating chametz on Passover is the divine punishment of kareth (cutting off).
Chametz is a product that is both made from one of five species and has been combined with water and left to stand raw for longer than eighteen minutes (according to most opinions) and becomes leavened.
The adjective chametz is derived from the common Semitic root Ḥ-M-Ṣ, relating to bread, leavening, and baking. The related noun chimutz is the process of leavening or fermenting. It is cognate to the Aramaic חמע, "to ferment, leaven" and the Arabic حَمْض ḥamḍ, "acid", حَمُضَ ḥamuḍa "to be sour", "to become acidic", "to acidify". This root relates to acidity and sourness in Hebrew as well, as the word chometz - חומץ - means vinegar, and the word chamootz - חמוץ - means sour.
All fruits, grains, and grasses for example naturally adhere wild yeasts and other microorganisms. This is the basis of all historic fermentation processes in human culture that were utilized for the production of beer, wine, bread and silage, amongst others. Chametz from the five grains is the result of a natural microbial enzymatic activity which is caused by exposing grain starch—which has not been sterilized, i.e. by baking—to water. This causes the dissolved starch to ferment and break down into sugars which then become nutrients to the naturally contained yeasts. A typical side effect of this biological leavening is the growth of the naturally-adhering yeasts in the mixture which produce gaseous carbon dioxide from glycolysis which causes the fermented dough to rise and become increasingly acidic.
According to the Talmud, chametz can only consist of grains of five species of grain. Other species are considered not to undergo "leavening" (chimutz), but rather "spoilage" (sirchon), and thus cannot become chametz.
At least four of the five grains contain high levels of gluten. The fifth grain (shibolet shual) is translated in Ashkenazi Jewish tradition as "oats" (which are low in gluten), but many modern scholars instead understand it to be a variety of barley (high in gluten). If the latter opinion is correct, then all five grains are high in gluten. That suggests that gluten is a necessary component of chametz, as it holds the dough together while rising, allowing the formation of a fluffy bread loaf.
Leavening agents, such as yeast or baking soda, are not themselves chametz. Rather, it is the fermented grains. Thus yeast may be used in making wine. Similarly, baking soda may be used in Passover baked goods made with matzoh meal and in matzoh balls. Since the matzoh meal used in those foods is already baked, the grain will not ferment. Whether a chemical leavener such as baking soda may be used with flour in making egg matzoh is disputed among contemporary Sephardic authorities. In accordance with those who permit it, cookies made with Passover flour, wine and a chemical leavener (the absence of water would make them similar to egg matzoh under the chametz rules) are marketed in Israel under the name "wine cookies" to Sephardim and others who eat egg matzoh on Passover.
The Torah specifies the punishment of kareth, one of the highest levels of punishment in Jewish tradition, for eating chametz on Passover (Exodus 12:15). During Passover, eating chametz is prohibited no matter how small a proportion it is in a mixture although the usual rule is that if less than 1/60 of a mixture is not kosher, the mixture is permitted. If the dilution happened before Pesach, the usual 1/60 rule applies; however, Ashkenazi Jews apply this leniency only if the mixture is liquid.
Also, hana'ah (any benefit, such as selling) from some forms of non-kosher food is permitted, but no form of benefit may be derived from chametz during Passover. Mixtures consisting of less than 50% chametz that are not usually consumed by people (such as medicine or pet food—even if perfectly edible) may be owned and used on Passover but may not be eaten.
See also: Passover § Removing all leaven (chametz)
See also: Eliminating Ḥametz
In addition to the Biblical prohibition of owning chametz, there is also a positive commandment to remove it from one's possession. There are three traditional methods of removing chametz:
It is considered best to use both bi'ur and bittul to remove one's chametz even though either of these two methods is enough to fulfill one's biblical requirement to destroy it. Mechirah, which averts the prohibition of ownership, is an alternative to destruction.
See also: Passover § Sale of leaven
In many Jewish communities, the rabbi signs a contract with each congregant, assigning the rabbi as an agent to sell their chametz. The practice is convenient for the congregation and ensures that the sale is binding by both Jewish and local law.
For chametz owned by the State of Israel, which includes its state companies, the prison service and the country's stock of emergency supplies, the Chief Rabbinate act as agent; since 1997, the Rabbinate has sold its chametz to Jaaber Hussein, a hotel manager residing in Abu Ghosh, who puts down a deposit of 20,000 shekels for chametz worth an estimated $150 million.
According to halakha (Jewish law), if chametz is found during Shabbat or Yom Tov, it must be covered over until Chol HaMoed, when it can be burned. Chametz found during Chol HaMoed (except on Shabbat) should be burned immediately.
After the holiday, there is a special law known as chametz she'avar alav haPesach (chametz that was owned by a Jew during Pesach). Such chametz must be burned, since no benefit is allowed to be derived from it, not even by selling it to a non-Jew. Chametz she'avar alav haPesach may not be eaten by Jews after Pesach. If a store owned by a Jew is known not to have sold its chametz, a Jew may not buy any from that store until enough time has passed in which it can be assumed that the inventory has changed over since Pesach.