PESAH: What is (and what is NOT) Hamets, and what is seor or natural yeast?

מ”ת הלכות חמץ ומצה א: ב

Out of the eight Mitsvot of Pesah we mentioned yesterday (see below), six relate to Hamets. During Pesah we are  not allowed to eat, benefit from or even possess Hamets.

Today we will explain what is Hamets and what is seor.

Hamets (aka chametz) is any fermented substance, solid or liquid, which comes from one of the following five grains: wheat, rye, spelt, barley and oats. These are also the five grains which are generally used to make bread. Our sages established that only for a bread made from one of these five grains we say the berakha “HaMotzi” and  “Birkat Hamazon”. If a bread is made, for example, from soy flour or rice or corn, it is not considered real “bread”.

The fermentation process does not only occur with flour that comes from these grains. Beer for example, is made from barley grains, which are soaked and then fermented. Beer (like whiskey) is Hamets, although the grain was never converted into flour.

A fermented food which does not come from or does not contain any of these five grains cannot become Hamets, even if it underwent a fermentation process. For example, wine goes through a fermentation process, but it is made from grapes. The same applies to other alcoholic beverages such as sake, which is made from fermented rice.

Not everything that comes from these five grains is hamets. In fact Matsa can only be made from one of these five grains. Matsa is also a kind of “bread”. In Hebrew it is called the bread of poverty or לחם עוני, and in English is called “unleavened bread”

What is the difference then between bread and Matsa?

The fundamental difference between bread and Matsa is time.

Bread and Matsa are made with the same basic ingredients: flour and water. The difference is: when preparing Matsa, once the flour is mixed with water, you cannot leave the dough to rest. The dough must be kneaded and baked in less than 18 minutes. Because if left idle for 18 minutes or more, from the time the flour got in contact with water, that dough is considered fermented. This fermentation is called in Hebrew “Himuts”, and the product of this fermentation is called “Hamets”.

Normal bread is made with flour and water, but the dough is deliberately left to rest. When fermented, the dough is enlarged and the bread crumb, i.e., the soft, inner part of bread, is formed.

If the flour from one of the five grains is mixed “exclusively” with fruit juice, or honey or eggs without any water, the fermentation or Himuts will not take place. Technically, if I make a dough by mixing wheat flour with pure fruit juice, with no water, and I bake the dough after it rested for more than 18 minutes, this will be called Matsa Ashira, and it is not considered Hamets.

In all these examples, we have not talked yet about yeast, or שאור in Hebrew.

The prohibition of Hamets includes also the banning of the use of yeast. Yeast is not an edible element, but an additive. Until a century ago yeast was produced at home. How was yeast prepared? Flour and water are mixed and kept for a period of four days. That sour dough, which smells like alcohol, is known as  “natural yeast” (or”sourdough”) and it is used as a catalyst in the process of fermentation. In other words, once flour and water are mixed, if we introduce some yeast into the dough, the fermentation process will accelerate, the dough will grow bigger and produce a spongious and tasty bread.

All Hamets restrictions (use, possession, benefit) also apply to se-or, natural or commercial yeast