Science of Baking Class
Lesson 6: Flours
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Introduction: Flours

Flour is the powdered form of wheat, seeds, nuts, or roots. It is made by grinding uncooked grains (seeds, nuts, or roots) into a fine powdery texture.

Flour serves as the main, or base, ingredient in most baked goods. When liquid is added to flour, two proteins (gliadin and glutenin) are transformed into gluten bonds, or strands, which acts as a sort of glue to hold ingredients together, creating a dough or batter. These gluten bonds give elasticity to dough creating a chewy texture. It’s also what gives baked goods their structure. Depending on the strength of the gluten bonds that form (or how much liquid is added), the texture (or crumb) of a baked good will change. Gluten is found in wheat, rye, barley and triticale.

There are many different types of flour and you will find numerous varieties on the grocery store shelves, mostly wheat varieties. Below we will discuss the most common types, what they are made up of, and how they are best used.

Anatomy of a Wheat Kernel

A wheat kernel consists of three parts: endosperm, bran, and germ. These parts can be separated and used individually, or ground together and used as a whole.

Endosperm – The innermost part, or center, of a wheat kernel is called the endosperm. It is a source of soluble fiber, B vitamins, trace minerals, carbohydrates, and iron. The two gluten proteins are also present in the endosperm of the wheat kernel: gliadin and glutenin. The protein, gliadin, is what a person with Celiac disease has a reaction to. Endosperm makes up most of a wheat kernel - about 83%. All-purpose flour is ground endosperm.

Bran – Wheat bran (left side of above photo) is the outermost coating of the kernel. It is the housing and protects the seed. Wheat bran provides insoluble fiber, some B vitamins, and trace minerals. It makes up approximately 14% of the kernel. Many common breakfast cereals are made with, or contain, ground bran. Wheat bran also makes delicious bran muffins.

Germ – Wheat germ (right side of above photo) makes up about 3% of a wheat kernel. It contains fat, vitamins, trace minerals, and antioxidants. Since wheat germ contains fat, it is removed from all-purpose flour to increase shelf life and slow spoilage. Wheat germ can be used as a filler or coating in cooking, but can also be toasted to add a rich nutty flavor to baked good recipes.

The germ is the embryo of the wheat kernel and is where a sprout forms when exposed to moisture. Wheat germ can also be found in oil form, to be used in cooking.

All-Purpose Flour

If you walk to your pantry and look for flour you will most likely find an all-purpose variety. AP flour is fine in texture and is milled from the innermost part of the wheat kernel called the endosperm. It’s often referred to as white flour or refined flour. It does not contain germ or bran and may or may not be enriched or bleached.

Enriched means nutrients are added back into the flour because they have been lost during processing.

Bleached means a bleaching agent has been added during processing to make the flour whiter in color.

All-purpose flour has a 10-12% protein content making it a great option for cookies, muffins, brownies, pies, and other common desserts. It is the most common type of flour in baking. If a recipe calls for 'flour' and doesn't specify a type, use all-purpose flour.

Whole Wheat Flour

Whole wheat flour, or wholemeal flour, is on the rise in popularity. It is not as processed as all-purpose flour since it contains the entire wheat kernel (germ, bran, and endosperm), making it a healthier option.

Whole wheat flour can easily be made in a home kitchen by grinding whole red wheat berries in a mill. Red wheat berries are darker in color and have a more grainy texture than all-purpose flour. Whole white wheat berries are also available which will produce white whole wheat flour (lighter in color and airier in texture).

**Should you choose to grind your own wheat at home to make flour, I highly recommend against the mill you see in the photo above! It takes forever (three or four grindings) to get a soft enough consistency to bake with. It looks rustic and nice, but it's not your friend. :) If you decide to purchase one, I suggest an electric mill.

Since whole wheat flour contains the bran and germ, it is more absorbent than AP flour and requires more liquid in a recipe. It will produce a denser texture and can be used for quick breads, scones, pancakes, waffles, and other baked goods. It has a higher protein content of about 13-14%.

Whole wheat flour can be substituted for any recipe that calls for all-purpose flour. Use ¾ whole wheat flour for every cup of AP flour.

Pastry Flour & Cake Flour

Pastry Flour – Pastry flour has protein content of about 9% which is lower than AP or whole wheat flour. Having a lower protein content means less gluten (or chewy, dense texture) can be formed. It is generally used as a substitute for AP flour when a more delicate pastry is preferred. It is very fine in texture and can be used to make pie crust, cupcakes, croissants, biscuits, and donuts.

Cake Flour – Cake flour is very similar to pastry flour but has a slightly lower protein content (approximately 7-8%) which is a result of the bleaching process which breaks down proteins. The low protein content results in light and airy baked goods and like the name states is best used for cakes and cupcakes.

How to Make Cake or Pastry Flour

To make your own cake or pastry flour you will need:

  • 1 cup measuring cup
  • 1 tablespoon measuring spoon
  • Medium sized bowl
  • Sifter or fine mesh strainer
  • 1 cup all-purpose flour
  • 2 tablespoons cornstarch

This is a great option for the home baker who doesn’t need an entire bag of specialty flour sitting in the cupboard! This most likely won’t result in the exact protein content of the specific flours but will be close enough to get a light airy texture in any recipe calling for cake or pastry flour. The simple act of adding cornstarch to AP flour (in the exact amounts listed) will lower the protein content to that of store-bought cake or pastry flour.

1. Measure one cup of all-purpose flour and place in a medium bowl.

2. Remove two tablespoons of flour and add two tablespoons of corn starch in its place.

3. Sift into a medium bowl to combine the flour and cornstarch. Repeat two or three times to make sure the ingredients are very well incorporated. Make more depending on the amounts needed!

Gluten-Free Flours

Like eggs, wheat is one of the top allergens and may need to be avoided. Although they don't work exactly the same as wheat flour (because they don't produce gluten), there are many wheat-free/gluten-free flour options available. Unless you are using a one-to-one gluten-free flour mix (meaning one cup of this kind of gluten-free flour can be substituted for one cup of wheat flour), these types of flour cannot be used interchangeably for wheat flour. It's best to follow the recipe and directions exactly if you choose to bake gluten-free.

Grain Flours - Oat, Corn, Amaranth, Bean, Pea, Millet, Rice, and Teff flours are among the most common gluten free, grain flour options. They are milled from the dried version of each grain. They are often used in conjunction with other flours (all-purpose or whole wheat) to make breads, pancakes, and tortillas.

Nut Flours & Meals – Almond, coconut, hazelnut, pecan, and walnut are common high protein, high fat, alternatives to wheat flour. Almond flour is the most prevalent of the nut flours. It has a relatively neutral flavor and is a common choice for those on a gluten-free diet.

You can find blanched and unblanched almond flour/meal varieties.

Blanched means the almond (or nut) skins have been removed before processing, giving the flour a lighter color and texture.

Unblanched means the skins are left on. This is called almond (or nut) meal.

Nut flours and meals can be used alone or in combination with wheat flours to make just about any baked good. Nut flours can be conveniently made at home by grinding blanched or unblanched nuts in a food processor. Just be careful how long you process the nuts. They will eventually turn to nut butter!

Tuber & Root Flours – Potato, Arrowroot, Cassava, and Tapioca are starchy flour alternatives used mainly in gluten free flour and gluten free baking. The roots are dried and ground into a very fine powder...much like the consistency and texture of cornstarch.

Gluten-Free Flour – Gluten-free flour is a combination of grain free flours and starches that do not contain any gluten. Like the options above, this is also an alternative for those who have celiac disease or who avoid gluten. If you choose to use gluten free flour you will ultimately end up having to experiment with different kinds/brands.

Although there are one-to-one (meaning any recipe that calls for one cup of flour can be substituted with one cup of this kind of gluten-free flour) options, they do not behave exactly like flour. If you don't have to avoid gluten, I recommend using traditional flours for the best results in baking.

Sift & Measure

When a recipe calls for one cup of flour it's necessary to have a little over 4 ounces in weight. One might be tempted to dunk a one cup measuring cup into the bag of flour, pull it out, and dump into a mixture. Or even worse, pack the flour into the measuring cup. Both of these methods will inevitably result in too much flour. This can be devastating to your final product.

How to Sift Flour

Sifting flour is a step often missed or purposely left out, but it is actually really important. Why? Along the way from the flour mill, to the processing plant, to the grocery store shelves, to the home pantry, flour is unintentionally packed down in its bag. Sifting flour removes any and all lumps, aerates/lightens, and makes it easier to mix into a batter or dough. This is also an opportune time to evenly distribute other dry ingredients into the flour before it gets added to wet ingredients.

Sifting can be done using a flour sifter or fine mesh strainer. To use a flour sifter, simply turn the side crank and sift into a bowl. To use a fine mesh strainer, simply place flour in the strainer. Gently and repetitively hit the side of the strainer (over a bowl). The flour will fall through the holes.

The photo above shows just how much the texture and consistency changes when flour is sifted.

How to Properly Measure Flour

Accurate measuring in baking is essential, especially in the case of flour. If too much flour is added to a batter or dough it will result in a very dry and crumbly texture. It's not hard to measure properly — here are four options to get you started. Find which one works best for you and use it every time you bake!

Option 1: – Gently stir flour in its bag (or canister) until it feels soft. Spoon the stirred flour into a measuring cup until it is mounded taller than the rim of the cup. Using the handle of the spoon or a table knife scrape the excess back into the bag. This is the least favorable option simply because the flour does not aerate as much as with proper sifting, but does result in about the same weight.

Option 2: – Place flour in a hand sifter or fine mesh strainer and sift the flour directly into a measuring cup. Sift until the flour mounds over the rim and scrape the excess back into the bag. Surprisingly, this will end up weighing slightly more than using option 1 or 3. There is no excess air in the sifted flour so it can pack into every crevice of the measuring cup.

Option 3: – Sift a large amount of flour into a bowl using a sifter or a fine mesh strainer. Spoon sifted flour into measuring cup and level off with the flat edge of a knife.

Option 4: – Some recipes call for flour (and other ingredients) specifically by weight. The easiest way to measure by weight is to place a bowl or measuring cup on a digital kitchen scale and zero out the weight of the bowl. On my particular scale this is done by pressing the ‘ON’ button after the bowl is resting on the scale. Most scales have a 'tare' button that will zero out the weight. Start spooning flour into the bowl until desired weight is achieved.

Up Next: Lesson 7 — Leavening Agents

All baked goods need to rise in some way while in the oven and there are many ways to achieve airiness. I bet you will learn something you didn't already know in the leavening lesson!