[Note: I owe a great deal in my analysis of the three types of leavening to a friend of mine from my days in Los Angeles, Dr. Hoover, who was the first person I remember hearing discuss leavening beyond the usual chemical means. I therefore wish to share such insights originally heard from him with others who may be unaware.]
This is the time of year when I and many of my friends remove leavening from our houses (and vehicles), carefully checking boxes and food items to make sure that there is no leavening in them so that we may keep the Days of Unleavened Bread. However, yeast and baking soda and baking powder are merely one of the three ways in which bread products can be leavened. If we wish to truly keep the Days of Unleavened Bread, we must have a wider understanding of leavening than chemical leavening alone. It is therefore the goal of this particular note to help inform those who wish to keep the Days of Unleavened Bread (or to know more about it) to understand leavening in its fuller context.
The most familiar type of leavening to most people who seek to remove leavened products from their homes is chemical leavening. This type of leavening is easy to recognize because one can read the ingredients on the side of the box to determine that leavening is present. The ease of discovery of chemical leavening and the lack of work one has to do to discover leavening means that this is the type of leavening that is most frequently recognized. Those who are unaware of leavening may falsely assume that simply by removing this type of leavened product from their homes they are fulfilling the biblical command to abstain from unleavened bread, but that would be a mistaken assumption, as this is merely one type of leavening.
Chemical leavening, technically speaking, refers to the use of chemical means to combine an acid and a base to create the carbon dioxide of leavening along with a chemical salt. Though adding yeast to a product is itself biological leavening, the pre-packaged nature of baker’s yeast in the present days is analogous to the chemical leavening found in baking powders and is present on the ingredients of foods, so it is included here under this type as well because it is easy to discover.
Chemical leavening has been around since the late 1700’s (1796 to be precise, at the latest), when Amelia Simmons noted the leavening tendencies of pearl ash . Typically speaking, chemical leavening uses two different agents to create a chemical reaction in a food like a quick cake or cookies. One is an acid, like sodium bicarbonate, calcium phosphate, or some sort of sodium phosphate, or ammonium bicarbonate, and the other is a base like cream of tartar, pearlash, or hydorgen peroxide. When chemically combined either separately or in a baking powder, the two create a salt and the carbon dioxide of leavening, making a bread soft and smooth in texture.
However, chemical leavening, though easy to recognize, is only one of three means by which leavening occurs. Throughout the course of human history the main form of leavening used by mankind has been natural leavening. This type of leavening can also be called biological leavening because it takes advantage of the yeast that naturally can be found in the air. The fact that yeast is naturally present in the air means that no one can completely deleaven their homes (no matter how hard they try), and also ensures that simply looking at the ingredients on a box for yeast or baking powder or soda of some kind will be insufficient to avoid leavened bread.
During the time of the Exodus, it seems quite likely that the most prevalent form of leavening was the use of a sourdough “starter” to leaven a whole lump quickly (what Paul means when he says, “A little leaven leavens the whole lump” in Galatians 5:9, also talking about sin). Additionally, biological leavening also takes place when dough is left out in the air to make sourdough bread, or when beer is made by yeast fermenting the “hops” (a bread product) and making a leavened bread drink product that many people may unknowingly drink during these days contrary to biblical law . Wine would not be leavened bread, nor would wine vinegar, but malt products would be considered “leavened bread” under biblical law and therefore unacceptable for the Days of Unleavened Bread. Nor is beer the only type of product that can be used to create “natural leavening”–the same is true of buttermilk and yogurt, meaning any bread product with beer, buttermilk, or yogurt would be a leavened bread product .
The third type of leavening is even more subtle, and it is in this area that perhaps the most common mistakes can be made concerning leavened products are made. Mechanical leavening (which includes leavening by the use of “creaming” or through the use of cream and egg whites, cooking bread with steam, or the use of whisking in bread products). All of these means are leavening because they serve to mechanically induce the yeast in air to react with food items to produce “structure” to a bread product.
Many breaded products are made through the use of mechanical leavening in ways that are not obviously “leavened.” The use of whipped cream makes bread products leavened by mechanical means, by foaming the buttermilk of a cream. Likewise, steam gives structure to bread by holding in the steam (and the yeast in the air) and giving the bread the structure and form of leavening in items such as popovers or tempura. Whisking in foods like angel food cakes leavens the bread by foaming the cream as well. Creaming, as in making cookies, integrates the yeast in air with a bread through the use of sugar cutting through the fat and allowing air bubbles to form within the cream. All of these mechanical means create leavened bread, even without adding chemical products, and are to be avoided during the Days of Unleavened Bread.
Therefore, as the Days of Unleavened Bread approach, let us go beyond merely removing yeast, baking soda, and baking powders from our fridge and pantry. Let us also abstain from taking advantage of natural or mechanical means of exploiting the leaven that is present naturally within the air to leaven products unknowingly or indirectly. Let us remember that whisking or creaming or steaming bread products is itself taking advantage of the leaven in the air. Let us also remember that sourdough products, beer, and using yogurt or buttermilk to make bread also breaks the command against leavened breads during this time of year. Let us therefore obey the Bible fully, rather than only partially, and gain a greater understanding of the many ways in which bread can be leavened. In doing so, may we also gain a greater understanding of the way that sin, like leavening, is in the air all around us, and can leaven our own lives in indirect and unexamined ways. Therefore let us examine ourselves as well as our pantries during this Passover season.