Winter 2024

The baalei mussar, our guides in ethical character development, have instructed us that in order to develop and refine one’s behavior, one has to control one’s temper.

Controlling temper in manufacturing is a means to refine and improve the quality of the product in question. When steel is tempered, the resiliency of the steel is improved through the process of heating and cooling. When chocolate is tempered, through a similar process of heating and cooling (albeit at a much lower temperature), the chocolate acquires a lustrous, luxurious sheen, impervious to changes in color.

Likewise, tempering grain for milling improves the grain so that the final product – wheat flour – is rendered white and fluffy. The source of this final product is the humble wheat kernel.

A wheat kernel or berry is the seed of the wheat plant and is comprised of three edible parts: the nutritious bran wrapped protectively around the entire berry and lined with the structurally significant aleurone layer; the vast starchy interior called the endosperm; and the germ, which is essentially the embryo of the plant that enables it to reproduce. Milling is the process of separating the bran and germ from the endosperm and refining it into flour.

If the grain were to be ground in its entirety, the result would be a brownish flour that we would recognize as whole wheat – as the name indicates. But how does the miller succeed in producing the pristine, fluffy white powder that constitutes regular, all-purpose flour? How does he manage to separate the brown bran from the white endosperm? He tempers the grain!

How Grain is Tempered

Tempering is a process in which the grains are wetted long enough so that water permeates the bran. This process of hydration makes the bran less brittle and helps loosen it so it can separate into large pieces, which are more easily sifted away from the flour when the grains are milled. Water also mellows the endosperm, making it easier on the grinders.

This “loosening” mentioned above can be attributed to the aleurone layer, which is a layer of cells just inside the bran layer. Chris Dengler, a lab analyst at Snavely’s Mill, helpfully compares the aleurone layer in a cross-section of a wheat kernel to flat tires. Upon tempering, these cells “inflate,” creating a separable layer between the endosperm and the bran. This action creates the void that allows the bran to be easily cleaved from the endosperm on a roller mill.

Mr. Dengler explains the process further: the wheat is placed in a tempering auger with paddles on it – which agitates the wheat – and is sprayed with water. The wheat is then transferred to a tempering bin to allow the water to soak into the grain for up to twelve hours and to dry out before being transferred to the mill for grinding. Tempering times can vary from three to twelve hours, depending on the type of wheat; for hard wheat, it could be even longer.

Once dry, the grains are augered into the break rolls. The first step of milling is referred to as the first break. The grain passes through a grain auger, which is a screw-shaped conveyor used to deposit or retrieve grain into or from a bin or silo for further processing. Once the grain is “broken,” it passes through a series of sifters. In a modern mill, there can be more than twenty sifters where the bran is separated and the endosperm is converted into white flour.[1]

At Snavely’s Mill, Mr. Dengler not only checks incoming wheat for moisture levels but also for enzymatic activity, a concern in wheat that was left to mature in the field and may have been exposed to soaking rains before being harvested. Enzymatic activity is another term for sprouting or malting. (Unlike with tempering, the process of intentionally sprouting grain involves immersing it in water and soaking it for several hours, which causes the moisture of the grain to increase to 40% or more.) Flour from sprouted wheat creates problems for bakers and is an undesirable product from a flour miller’s perspective. Tempered grain does not lead to sprouting. 

SIDEBAR: Halachic Implications of Whole Wheat vs Whole Grain Flour

It is important to note that commercial whole wheat flour is commonly produced by adding the separated bran back to the sifted white flour after milling. This has halachic implications regarding the amount of flour required for hafrashas challah. Since the bran is added to the flour after milling, it is viewed as a separate component, and thus cannot be included in the calculation to determine the volume of flour. If the bran and endosperm were milled together, it would be regarded as a single entity.

Tempering Implications During Pesach

Since water does penetrate the endosperm of tempered grain, we are confronted with a number of questions relating to Pesach. How does halacha view the tempered grain? How does flour differ from all other chometz items in one’s pantry? Is a kosher consumer who does not sell vadai chometz required to sell her flour before Pesach?

Tempering grain is not a new milling technique. It was a front burner issue in the Gemara where the halacha is clear. Lesisa – tempering grain to make flour for matza – is forbidden. In fact, in contemporary matza flour milling, all boxed matza produced in the U.S. is made using non-tempered grain. A miller who operated the Spangler Mill once commented that he could hear the “cracklin’ bran” when they milled the matza flour.

The Rambam cites a case of a boatload of grain that was submerged in water.[2] The inundated grain was deemed vadai chometz because there was no movement in the water. The Bais Yosef even added this caveat: even if the grain didn’t sprout, it is considered chometz since the grain was stationary.

The Mishna Berurah analogizes the submerged grain to lesisa tempering but adds that the grain has to be close to sprouting to be considered vadai chometz.[3] The Rema concurs. In contrast, the Shaar Hatziyun, while acknowledging those poskim who consider tempered grain as being vadai chometz, rejects their opinion by noting that we do not know exactly when the grain is considered sprouted and, furthermore, by observing that the grain is hard.[4] He is actually describing a modern-day tempered grain. He ends by concluding that a dry grain, which is the case with a tempered grain prior to milling, would not be considered vadai chometz. Yet, one cannot discount the fact that water did penetrate the endosperm, so the grain – and, therefore, the tempering – would deem the flour safek chometz.

There are at least two compelling reasons to deem the flour safek chometz. The first, as noted above by the Shaar Hatziyun, is that we see that the grain is hard and we cannot be sure at precisely what point the grain will sprout.

A second reason is offered by Rabbi Moshe Heinemann, STAR-K’s Rabbinic Administrator. He posits that there is an ironclad scientific basis for considering tempered grain to be safek chometz. Millers need the grain to be dry enough to mill efficiently and they therefore set the moisture level of incoming wheat to no more than 14%. Mr. Dengler points out that wheat that arrives at their mill with a higher moisture content is routinely rejected. When wheat has been properly dried, either in bins at grain elevators or at the farm, it is very stable and can be stored for very long periods of time without any germination – in some cases, even for years. 

Sprouting only occurs once the moisture level reaches 22-24%, typically seen in wheat that was subjected to heavy rain after fully maturing. In view of that observation, Rabbi Heinemann rules that we can rely on accepted scientific standards to consider tempered grain as non-sprouted.

The Bottom Line

What are the halachic consequences of this conclusion? One who doesn’t sell vadai chometz before Pesach may sell his flour. Likewise, one who doesn’t purchase sold chometz after Pesach may purchase flour immediately after Pesach. This ruling on flour surely makes life easier for the scrupulous kosher consumer. And it definitely shows the wisdom of our gedolei haposkim who really understood how to control their temper!

The author wishes to thank Mr. Chris Dengler for his assistance with this article and for sharing his extensive knowledge about all things grain. Mr. Dengler is a lab analyst with Snavely’s Mill Inc. in Lititz, PA.

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[1] As a point of note, in the Beis Hamikdash, there were thirteen sifters.

[2] Pesachim 40b.

[3] O.C. 467:2.

[4] O.C. 467:11.