Science Lesson

The Wheat Kernel:  Parts and Functions

A kernel of wheat has three main parts:  the bran, germ, and endosperm. Each part has a special job to do, and for the baker, it is important to understand a little bit of the role each part plays.


Starting with the bran, which is really the outer surface of the endosperm. It serves as the protective layer for the germ and endosperm. It is comprised of cellulose and minerals.

The germ accounts for only a small percent of the wheat kernel, but it makes up for its small size in big nutrition. It is packed with vitamins, minerals, and fats. When you plant a kernel of wheat (which is the seed), it is from the germ that the first root and sprout emerge.

For those of us relying on gluten to strengthen, shape, and expand our breads, the endosperm is the most important part of the kernel. It is here that we find the proteins glutenin and gliadin, which when combined with water, form gluten. Along with these proteins, the endosperm also serves as the storehouse for starch and water. It is the long-term nutrition provider for the whole kernel.

Wheat Flours: Whole, Straight, Patent, and Clear

Before I started baking, I just thought flour was flour. There was white flour and brown flour. Apparently not. Flours made from wheat berries, especially flours milled from the endosperm of wheat berries, offer a spectrum of behaviors and flavors when considering them for bread making.

Whole-wheat flour is flour from the whole wheat berry after it has been ground. It is usually sold as fine, medium, or coarse.

White flour, on the other hand, is flour milled from the endosperm of the wheat kernel. There are three main streams of flour we get from this: straight, patent, and clear. When the entire endosperm has been ground, sifted, and reblended it is known as “straight” flour. “Patent” flour is flour milled from the center of the endosperm, and it is considered the best for bread making. Flour ground from the outer part of the endosperm is known as “clear.” It has a higher protein level than “patent” flour and is darker in color due to greater amounts of minerals.

The baker can use this information to make any number of breads and to manipulate dough into desired outcomes. The important part is to find a flour that works for you. One that performs consistently and gives you a bread that you can be proud of.


2 responses to “Science Lesson

  1. Hi. Totally love your term “Honest Bread” for sourdough! I am wondering if you ever posted concerning proper preparation of sourdough and the possibility of better digestion tolerance for those with non-celiac gluten sensitivity due to neutralized gluten/gliaden, phytic acid, oxalates, lectins… autoimmune antibodies years in advance… Wonderful site by the way!

    • Thanks for the kind words. I have a post titled “Culture” where you’ll find instructions for starting a sourdough culture. Otherwise, I’m not sure what you mean by “proper preparation of sourdough.” As far as gluten sensitivity goes, I’m no expert, nor do I have any posts related to gluten free alternatives. Anyway, glad you like the blog!

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