Machine-made shmura matzoMatzo (also Matzoh, Matzah, Matza, Hebrew מַצָּה ma ṣṣā) is a Jewish food item made of plain flour and water, which is not allowed to ferment or rise before it is baked. The result is a flat, crispy, cracker-like bread.

Matzo is the traditional substitute for bread during Passover. According to the Torah, when   the  Israelites   were  leaving   Ancient

Egypt, they had no time to wait until their bread rose, so they baked it before it had a chance to rise, and the result was matzo (Exodus 12:39). For Passover, the ingredients for matzo are limited to flour and water only, while other ingredients such as eggs or fruit juice may be added to matzo that is produced and consumed during the rest of the year.

Five grains

• Wheat,
• Barley,
• Spelt,
• Rye, and
• Oats (according to Rashi) (or two-rowed barley according to Rambam's interpretation of Mishnah Kilayim 1:1; Yerushalmi Challah 1:1).

Wheat and spelt (biblical spelt is now more correctly identified as emmer wheat) are both in the genus Triticum and anything else in the genus is likewise forbidden. Oat-grain is practically gluten-free and belongs to a different tribe than wheat, spelt, rye and barley. Millet and teff are borderline; it takes a few days for them to rise.

Dough made from the five grains is considered to start rising if it is inactive for 18 minutes from the time it gets wet; if longer elapses before it is put in the oven, it is no longer matzo.

Matzo can be ground to form coarse matzo farfel or fine matzo meal, which is often used as a substitute for flour in Passover cooking.

Common varieties
There are two major forms of matzo, with several subcategories. In the United States, the most common form is Ashkenazic matzo, which is cracker-like in both appearance and taste. Many Sephardic Jews use a soft form of matzo. In some Sephardic communities, matzo is similar to pita while in others it can resemble a tortilla.

Handmade shmura matzoAmong Ashkenazi matzo, one can distinguish between what is called shmura matzo — a round matzo about a foot in diameter — which is made by hand, and machine-made matzo, which is usually square and much smaller. Shmura ("guarded") matzo (Hebrew מַצָּה שְׁמוּרָה ma ṣṣā šəmūrā) is made from grain that has been under special supervision from the time it was harvested to ensure that no fermentation has occurred. In addition, it is made with the intention of using it to fulfill the commandment of eating matzo on the first night of Passover. When made by hand, shmura matzo is rolled and shaped in a circular form. When made by machine, shmura matzo is square.

(The same shmura wheat may be formed into either handmade or machine-made matzo, while non-shmura wheat is only fashioned into machine-made matzo. Moreover, although it is possible to bake shmura-style matzo from non-shmurah flour, such matzo is rarely produced.)

Machine-made matzo
Matzo-forming machine. Beginning of 20th century. The Lviv Museum of the History of Religion.Besides their shape, handmade and machine-made matzo taste distinctively different. Handmade matzo is dense and chewy, while machine-made matzo is lighter and crispy. Shmurah matzo is available only around Passover and is far more expensive than its commercial cousin.

Matzo ashirah (egg matzo)
Contrary to its popular name, egg matzos are matzos made with any liquid other than water. The name is usually used for matzos made with fruit juice, often grape or apple. (Egg matzo made with actual eggs is a rarity.) The Hebrew term for egg matzo is מצה עשירה (matzo ashirah, literally, "rich matzo"). Egg matzo cannot be used to fulfill the requirement of eating matzo at the Passover Seder. This is because such matzo would be considered "rich", while the matzo eaten at the Seder is called לחם עוני ("poor man's bread")

Although egg matzos are often sold as kosher for Passover, Ashkenazic Jews do not eat them during the entire holiday. However, it is often permitted for the elderly, infirm, or children who cannot stomach plain matzo. Many Sephardim do not have this stringency.

Matzo during the year
Commercial matzo is often available during the year, both in flavored and plain forms. It is used in cooking (e.g. matzo ball soup made from matzo meal) or eaten as a snack. During the year, Ashkenazim treat matzo as bread, requiring washing before and full Birkat Hamazon afterwards. Sephardim normally treat it as a cracker and accord it the special status of bread only during Passover.

References
Zohary, Michael (1982). Plants of the Bible. Cambridge: Cambridge University Press. ISBN 0-521-24926-0. Up-to-date reference to cereals in the Biblical world.