"Leaven" on Passover

Matzah: from an old Passover HaggadahMatzah: from an old Passover HaggadahOn Passover, we are given an additional kosher law:

Seven days you shall eat unleavened bread. On the first day you shall remove leaven out of your houses, for if anyone eats what is leavened, from the first day until the seventh day, that person shall be cut off from Israel. (Exodus 12:15)

The word translated "leaven" or "leavened bread" is the Hebrew word chametz (חמץ). It does not actually mean "leaven" or "leavening" in the sense that we use the word today. Chametz is any grain product in which fermentation has occurred. It is related to the word chamutz (חמוץ), which means "sour."

In ancient times as well as in breads such as sourdough today, bread could be leavened just by allowing the dough to sit for a period of time until enough of the yeast in the air works its way into it and begins to ferment the dough.

Keep in mind that the Hebrew word chametz does not imply anything about the fluffiness or softness of the food, but only that it has been fermented. This is one area where our English language leads us astray.

The Five Grains

Chametz is limited to grain products, which is borne out by the fact that wine and wine vinegar are present and consumed during Passover in the Gospels. This makes sense, because it was bread making at the time of the exodus that led to the prohibition of chametz. Bread, as it was known to the ancient Israelites, could be made of five types of grain.

The Hebrew terms for the five grains1 are:

There are multiple opinions as to the exact identity of some of these grains. The Orthodox Union offers this explanation:

Chittim is wheat, which by Talmudic times consisted of two primary species, durum and common wheat. Se'orim refers to 6- and 4-rowed barley, two of the three forms grown in ancient Israel. Kusmin, called kusemet in the Torah and associated with food for the poor (Ezekiel 4:9), is probably emmer. Shibbolet shi'al may be 2-rowed barley and, indeed, it and se'orim were considered as one species in regards to kilayim (prohibition of mixing heterogeneous plants in one field) (Mishnah Kilayim 1:1). Shippon refers to either spelt, a species of wheat, or einkorn, the granddaddy of all modern wheat. Since shippon and kusmin were considered as one species in regards to kilayim (1:1), spelt is the more likelier choice as it is a closer relative to emmer. Oats and rye, which shibbolet shi'al and shippon are commonly mistranslated, neither grew in Israel at that time nor are closely related to the various species of wheat.2

Since other products that we conventionally think of as grain (such as rice or corn) would not have been accessible to ancient Israelites, they do not constitute chametz.

One might ask: is that really reasonable to limit chametz to those five grains? After all, there are other biologically similar cereal grains in which fermentation can also occur, such as corn (maize) or rice. Ashkenazi custom places those grains, along with legumes and certain other foods, in a different category called kitniyos. Certain Jewish communities choose to avoid kitniyos in addition to chametz because they could be easily confused, but not because of an explicit commandment in the Torah. But is that classification correct, or should maize and rice be prohibited as a matter of Torah law?

As previously noted, our translations are misleading with the term chametz, filling in its literal meaning ("something fermented") with a more interpretive translation: "leavened bread." In reality, there are numerous things that could be fermented in addition to grain products. We are already conceding to Jewish tradition by accepting that chametz is limited to grains (although rightfully so, since the making of bread was the factor that led to the prohibition). It would not be fair to accept the traditional reading of chametz as grain, but then to use a different definition of what grain is.

While maize and rice are biologically similar to the five grains, biological taxonomy is markedly different from biblical taxonomy, as we have seen elsewhere in our kosher study. For example, the Bible classifies bats along with birds and whales along with fish. That is because the major biblical taxonomic classification is the domain in which the creature lives: those that teem in the water, those that crawl on the earth, beasts of the field, and birds of the air. It is reasonable to apply this also to plants. This suggests that a biological classification may not be useful from a biblical perspective; a classification based on native land is more in keeping with biblical thought.

For example, compare Egypt's choice foods: "the cucumbers, the melons, the leeks, the onions, and the garlic" (Numbers 11:5) with those of Israel: "a land of wheat and barley, of [grape] vines and fig trees and pomegranates, a land of olive trees and [date] honey" (Deuteronomy 8:8). Notice how those of Egypt all grow directly on the ground (downwards), whereas those of Israel, aside from grain, all grow in trees (upwards).

(One might mention that grapes don't grow on trees, they grow on vines. But there is another example of Biblical taxonomy at odds with biological taxonomy. Biblically, a grape vine is a tree as we can see from verses such as Judges 9:12, Ezekiel 15:2-6, and others.)

The Sages considered wheat and barley to be the primary grain species and the other three as subspecies. This would explain why the Scriptures so frequently mention wheat and barley, but so rarely mention the other three in any context, despite the fact that they did exist and were in use at the time.

Nonetheless, look at how many different terms for grain are used in the Torah, specifically in connection with Egypt:

The flax and the barley (se'orah, שערה) were struck down, for the barley was in the ear and the flax was in bud. But the wheat (chittah, חטה) and the emmer (kussemet, כסמת) were not struck down, for they are late in coming up. (Exodus 9:31-32)

And he fell asleep and dreamed a second time. And behold, seven ears of grain (shibbolet, שבלת), plump and good, were growing on one stalk. (Genesis 41:5)

Fermentation of Grain

Fermentation occurs whenever flour or grain comes in contact with water. It may or may not be perceptible in the form of fluffiness or taste. Fermentation is the process of yeast (which occurs naturally in the air) breaking the sugars into alcohol, releasing carbon dioxide. Since fermentation begins immediately, it is impossible to have bread in which absolutely no "leavening" has occurred (outside a laboratory). For all practical purposes, fermentation ends when the product is cooked. Thus, for bread to be "unleavened," there has to be a defined maximum amount of time between when the flour comes in contact with water and when baking is completed. The Bible does not tell us what that time is.

Jewish law defines chametz as any of the above-listed grain products that has been combined with water and has been allowed to sit longer than eighteen minutes before being fully cooked. This means that many foods you might not expect can be considered chametz, such as noodles, crackers, or cookies as well as both fluffy loaves of bread and flatbreads such as pitas or tortillas. Ultimately, that means any grain product in your house other than kosher-for-Passover matzah.

Grain vinegar is also a fermented grain product, and so it is forbidden. Grain vinegar is present in many foods, such as ketchup and mustard. If the label does not indicate what type of vinegar it is, it is probably from grain. Other vinegars such as from cider or wine are not prohibited, as long as they are not combined with grain vinegar as well.

Many alcohols are also produced from fermenting grain. Beer and many spirits are thus prohibited. Alcohols that are not made from grain are not prohibited, such as wine from grapes. Grain alcohol is present in many food flavorings, such as vanilla extract. It is probably present in trace amounts in any food that lists "natural flavors" on the label.

Other leavening agents (such as baking soda) that release gases through a non-biological process are not prohibited. So you wouldn't need to remove a canister of baking soda, although you probably shouldn't use it during Passover in a way that would involve combining flour with water.

Other types of microbiological processes are not prohibited, so foods with bacterial cultures such as yogurt or natural sauerkraut can be kept.

Most people remove flour before Passover as well. Flour is not chametz exactly, but if by accident or negligence your flour comes in contact with moisture it will create chametz, which would be problematic. Removing flour also removes that possibility.

The safest way to know if something is kosher for Passover is if a reliable kosher for Passover certification appears on the label.

  1. 1. Found in m.Challah 1:1.
  2. 2. Gil Marks, Open Tent Policy. http://www.ou.org/shabbat/recipes/tent.htm