What is white flour made out of?

January 1, 2026 •

4 min read

Over 80% of a wheat kernel's weight is composed of the endosperm, which is the primary component used to make white flour. This refined ingredient, a staple in many kitchens, is created through a meticulous milling process that strips away the outer bran and inner germ.

Quick Summary

White flour is produced from the starchy endosperm of the wheat kernel through a milling process that separates and removes the bran and germ. The resulting product is a fine, light-colored powder with a longer shelf life due to the removal of the fat-rich germ.

Key Points

Endosperm is the source: White flour is made exclusively from the endosperm, the starchy core of the wheat kernel.
Bran and germ are removed: The refining process involves separating and removing the nutrient-rich bran and fat-rich germ to create a fine, white powder.
Milling is a multi-step process: Wheat goes through cleaning, conditioning, and several rounds of break and reduction rolling to isolate the endosperm.
Refining impacts nutrition: Because the most fibrous and nutrient-dense parts of the kernel are removed, white flour has less natural fiber and nutrients than whole grain flour.
Enrichment restores nutrients: Many commercially produced white flours are enriched with vitamins and minerals lost during processing to improve their nutritional value.
Texture and flavor are distinct: The absence of bran and germ gives white flour a fine texture and milder flavor, unlike the coarser, nuttier taste of whole wheat flour.
Shelf life is extended: Removing the germ, which contains fat, prevents it from going rancid, giving white flour a significantly longer shelf life.

The Core Component: The Wheat Endosperm

To understand what white flour is made of, one must first look at the anatomy of a wheat kernel, or wheat berry. The kernel has three main parts: the bran, the germ, and the endosperm. The bran is the hard, protective outer shell, rich in fiber and minerals. The germ is the embryo of the seed, packed with vitamins and healthy fats. Finally, the endosperm is the largest part of the kernel, consisting mostly of carbohydrates and protein. It is this inner endosperm that is isolated and ground to create white flour.

The Milling Process: From Kernel to Flour

The journey from a wheat kernel to a bag of white flour is a multi-step process known as milling.

Cleaning and Conditioning

The process begins with the raw wheat kernels being thoroughly cleaned to remove any dust, stones, and other debris. The grains are then conditioned by adding a precise amount of water, which helps to soften the outer bran layers and make them more pliable. This conditioning helps ensure a cleaner separation of the endosperm from the bran during milling.

Break and Reduction

Next, the wheat kernels are sent through a series of rollers in a roller mill, a technology that revolutionized flour production over a century ago. These rollers, known as 'break rolls,' are set to shear open the grain, not crush it completely. This process separates the outer bran and germ from the starchy endosperm. After each pass through the break rolls, the different-sized fragments are separated by sieves. The endosperm fragments, or middlings, are then sent to a separate set of smooth 'reduction rolls' for final grinding into fine white flour.

Sifting and Refining

Throughout the milling process, the various components are continuously sifted to separate the fine flour from the coarser bran and germ particles. The bran and germ are collected as by-products, often used in other applications like animal feed or whole grain products. The resulting white flour, now consisting almost entirely of pure, ground endosperm, is ready for optional further treatment.

Optional Steps: Bleaching and Enrichment

Freshly milled white flour has a slightly yellowish tint, which naturally whitens as it ages through oxidation. However, some manufacturers use bleaching agents, like benzoyl peroxide, to accelerate this process. This gives the flour a brighter, whiter appearance and can affect the final texture of baked goods.

During the refining process, many of the essential vitamins and minerals found in the bran and germ are removed. To compensate for this nutritional loss, many countries mandate or encourage the practice of enrichment, where B vitamins (such as niacin, thiamin, and riboflavin) and iron are added back into the flour. This process improves the nutritional profile of the final product, although it still lacks the fiber content of whole wheat flour.

Comparison: White Flour vs. Whole Wheat Flour

The primary distinction between white flour and its whole grain counterpart lies in the parts of the wheat kernel used. While both originate from the same plant, the manufacturing process leads to significant differences in texture, nutritional value, and baking properties.


Feature	White Flour	Whole Wheat Flour
Composition	Made from only the endosperm of the wheat kernel.	Made from the entire wheat kernel, including the endosperm, bran, and germ.
Texture	Very fine and smooth due to the removal of coarser bran and germ particles.	Coarser texture due to the presence of bran and germ particles.
Color	A light, refined white color, sometimes bleached to appear even whiter.	A light brown or tan color, reflecting the inclusion of the bran and germ.
Nutritional Profile	Lower in fiber, vitamins, and minerals; often enriched after milling.	Higher in fiber, vitamins, and minerals; retains the natural nutrients of the whole grain.
Flavor	A more neutral, milder flavor.	A richer, nuttier flavor from the germ and bran.
Shelf Life	Longer shelf life due to the removal of the fat-rich germ.	Shorter shelf life because the fats in the germ can go rancid.
Baking Properties	Produces a lighter, airier texture, ideal for cakes and fine pastries.	Produces denser, heavier baked goods, common in hearty breads.

Conclusion

At its core, white flour is made out of the starchy endosperm of a wheat kernel, meticulously separated from the bran and germ through a modern milling process. This refinement results in a fine, white powder that provides a milder flavor and lighter texture for baking, albeit with less fiber and nutrients than whole wheat flour. Understanding this process helps clarify the fundamental differences between various flours and their uses in the kitchen. For those seeking more nutritional benefits, whole grain alternatives that retain all three parts of the wheat kernel are the better choice.

Frequently Asked Questions

The primary ingredient of white flour is the endosperm, which is the starchy interior of the wheat kernel.

No, white flour and whole wheat flour are not the same. White flour is made from only the endosperm, while whole wheat flour uses the entire kernel, including the bran and germ.

White flour is less nutritious because the milling process removes the bran and germ, which are the parts of the wheat kernel that contain most of the fiber, vitamins, and minerals.

White flour is naturally off-white but becomes whiter as it ages through oxidation. Some manufacturers use bleaching agents to accelerate this process and achieve a bright white color.

Enrichment is the process of adding B vitamins and iron back into white flour to restore some of the nutrients that are lost when the bran and germ are removed during milling.

White flour has a longer shelf life because the fat-rich germ is removed during processing. This prevents the flour from going rancid, which can happen with whole grain flours.

During the milling process for white flour, the outer bran and the inner germ are separated and removed, leaving only the endosperm to be ground into flour.