So What is Chametz?
In Torah, chametz is a fermented food using one, or more, of the five common grains used in Biblical times for bread making: barley, rye, oats, wheat, and spelt (BROWS), If these grains are mixed with water, they will begin to ferment. They will do so even if you do not add yeast to them, because they naturally pick up wild yeasts from the air.
Grain + Water + Time = Chametz
Any cakes, cookies, crackers, and baked goods that we eat the rest of the year are most likely chametz. Not because of the baking soda or baking powder used to make them rise, but because we make them from these five grains using water and time. In addition, commercial flours made from these five grains are commonly made from soaked grains. In the mills, they soak grains in a process called tempering. Tempering allows the bran and the wheatgerm to be easily separated out in the milling process, so almost all commercial flours are tempered. This water + time to temper means that flours also qualify as chametz.
This is actually what gives us the difference between matzah for Passover and matzah labeled as “not for Passover”. Matzah for Passover is made from wheat flour that has not been made from tempered grain. When the flour is mixed to make the matzah, there is only a short time period before it must be in the oven to be baked in order for it to remain “unleavened” for Passover.
So now we can see why wine, though made from yeast, is not chametz. Wine is made from grape juice and not one of the five grains. We do see wine labeled “for Passover” and that is because those wines have been certified to have used fermentation yeasts that were not originally grown on grains.
So What About Se’or?
Remember I said that people don’t wait for the wild yeast to make enough fluff in the bread so they add a portion of already “captured” yeast? This could be a sourdough starter, or some of yesterday’s leavened dough, or in our modern context, that package of yeast you use to make bread. That package of yeast was probably grown on a grain and concentrated and dried to make a convenient and consistent provision of these micro-organisms. So, yes, se’or is yeast… but then there is yeast that is not se’or. Se’or is yeast grown on those grains to leaven your bread.
The Bottom Line
So eat that matzah (there are some really yummy ways to do that!), don’t eat that chametz, and do not cling onto that se’or.
As we examine our homes, pantries, menus and plates for se’or and chametz, we also examine our lives, our hearts, the things we think, the things we say, and the things we do, for any trace of sin. Let’s not lose sight of the fact that this is a time appointed by HaShem for us to deal with our spiritual chametz as we search out the physical chametz. Chag Sameach!