About Wheat Flour

The Uniqueness of Wheat

WHAT MAKES WHEAT and its relatives different from other grains is gluten, an elastic protein polymer that forms hundreds of thousands of tiny balloons in dough that capture and hold the gases produced by fermentation and baking, and which cook into a springy, tender lattice when heat is applied. Although both barley and rye contain small amounts of gluten, wheat's high gluten concentration - about 80% of the protein content of wheat consists of the gluten-forming proteins gliadin and glutenin - is what makes it the preferred grain of bakers the world over.

Virtually all of the wheat grown in the world falls into five categories, which themselves are based on three criteria: the hardness of the wheat kernel, the bran color, and when the wheat is planted.

Kernel hardness is far and away the most important determinant of baking qualities. Soft wheats are generally high in starch and low in protein, making them most suitable for chemically leavened products like cake, cookies and some pastries. Hard wheat, on the other hand, is much higher in protein and stronger gluten quality, and are used in all breads, pizza crusts, and yeast- or steam-leavened pastries like cinnamon buns, babkas and puff pastry.

The bran color refers to the coating of the wheat kernel after the husk has been stripped away; it can be either red, which is slightly harder with greater gluten strength, or white.

Finally, when the wheat was planted also is an indicator of its quality. Winter wheat, which is planted in the fall in milder climates and overwinters in the fields, has protein content in the 10% to 12% range and a slightly softer kernel than spring wheat, which has stronger gluten-forming ability than winter wheat and contains 12% to 14% protein.

Based on these three criteria, the five main wheat categories are:

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The Milling Process

With one important exception - the transition from stone slabs that grind the grain to steel rollers that crush it - flour milling has remained largely unchanged for centuries. To understand the milling process, you first have to understand the anatomy of a wheat kernel.

A grain of wheat consists of three main parts: the bran, which consists of several outer layers that are rich in fiber, minerals and protein; the germ, which is rich in fat; the endosperm, which consists mainly of starch, and the aleurone layer, which surrounds the endosperm and contains high concentrations of protein, fat and minerals. If a grain of wheat were an egg, the bran would be the shell, the germ the yolk, the endosperm the white, and the aleurone layer the membrane just inside the shell.

The goal of milling is to separate the kernel into its constituent parts and to further break them down into different grades of flour. Millers do this by putting the grain through a pair of steel rollers called breakers that strip off the bran and germ, which account for about 17% of the kernel's weight , and crush the endosperm into particles of varying size and density.

The wheat then passes through a series of mesh screens that sort the endosperm particles by size. Blowers at each screen move the particles into distinct streams that may pass through additional sets of rollers and sifters or go into holding hoppers. In all, it takes about 20 minutes and passage through four or five pairs of rollers and dozens of sifters to mill a single kernel of wheat. On average, 100 pounds of wheat will produce 72 pounds of flour.

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Types of Wheat Flour

At the end of the milling process, the miller blends the streams together to form the flours that make up the baker's pantry, each with its distinctive properties, behavior and uses.

Straight flour consists of 100% of the endosperm and aleurone layer. In France, bread bakers typically use straight flours; it is rarely available in the US, however, except from artisan millers.

Patent flours come from the heart of the endosperm and are the purest, highest-quality commercial flours available. Depending on whether they're milled from soft or hard wheat and what percentage of the straight flour it represents - commonly referred to as its extraction rate - patent flours fall into one of five classes.

It's worth noting that flours with high extraction rates, i.e., a greater percentage of straight flour, also typically contain more protein and have correspondingly higher mineral and fiber content, as evidenced by the percentage of ash that a measured sample of flour produces when it's burned under very specific conditions.

Flour Type Wheat Extraction Uses
Extra Short (Fancy) Patent Soft 40-60% Cakes
First Patent Soft 60-70% Pastry, muffins, biscuits
Short Patent Hard 70-80% Bread, All Purpose
Medium Patent Hard 80-90% Bread
Long Patent Hard 90-95% Bread,bagels, pizza

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Millers blend patent flours into a wide variety of commercial flours, each of which is designed for specific applications, from delicate sponge cakes to crusty and chewy bread and rolls. In addition, millers may blend straight flour with bran and germ to produce whole wheat flour.

Clear flour is what remains after the patent flour is removed. Because clear flour comes from the outermost layers of the endosperm and the aleurone layer, it's generally much darker and stronger-flavored than patent flour, and also higher in protein, ash and fat. Clear flour comes in three grades:

Commercial Wheat Flours

Although flours are marketed under a wide variety of names and formulations, virtually all commercially available flours fall into these eight categories:

Type Protein Ash Applications
Cake Flour 7-8.5% 0.35-0.40% Cakes
Pastry Flour 8.5-9.5% 0.40-0.45% Pastries, pie crusts, cookies, muffins, biscuits
All-Purpose (Hotel & Restaurant) Flour 10-11.5% 0.45-0.50% Soft breads, pastries, pie crusts, cookies, muffins, biscuits
Bread Flour 12-13% 0.48-0.52% Artisan and soft breads and rolls, puff pastry, Danish
Strong Bread Flour 13-14% 0.52-0.55% Artisan breads, hard rolls, pizza crust, bagels
High-Gluten Flour 14-14.5% 0.52-0.55% Hard and highly enriched breads, rolls, pizza crust, bagels
Whole Wheat Flour 13.4-14% 1.60-2.0% Breads, blended with patent flour for other products
First Clear Flour 15-18% 0.80-0.90% Gluten contributor for rye and other breads with high percentages of non-wheat flours.

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A Note on Flour Additives

Once the milling and blending are complete, millers may also amend the flour with a variety of additives that can affect its nutritive value and behavior.

Enrichments return the nutrients lost in the milling process. To qualify as enriched, a flour must meet USDA minimum standards, which require that each pound of flour contain at least 2.9 milligrams of thiamin, 1.8 milligrams of riboflavin, 24 milligrams of niacin, 0.7 milligrams of folic acid, and 20 milligrams of iron, and may also contain added calcium.

In addition to vitamins and minerals, flour can also contain a wide variety of other additives, including:

Dough conditioners shortcut the biochemistry of dough fermentation by stimulating yeast growth, accelerating gluten formation to minimize mixing time, and softening the dough so that it won't clog machinery or require resting before shaping into rolls or loaves.

Some conditioners occur naturally, for example ascorbic acid, present in fruits and vegetables as Vitamin C, which aids the action of the yeast and deters mold and bacterial growth; and the enzymes amylase and diastase, which break starches and complex sugars down into simple sugars, thereby improving fermentation, and which occur abundantly in barley products such as flour and malt.

Other conditioners, like azodicarbonamide, L-cysteine hydrochloride. sodium stearoyl 2 lactylate, calcium stearoyl lactate, ethoxylated and succinylated monoglycerides, and polysorbate 60 are man-made substances and generally are regarded as benign by health regulators.

Bleaching agents accelerate the oxidation of flour, which occurs naturally over time, enabling millers to market their flour immediately, rather than waiting the 1-2 months needed for proper aging. That being said, all cake flours are bleached because bleaching improves gluten formation, which is adversely affected by the high-sugar and high-fat concentrations typical of cakes, cookies and pastries. First clear flour also is normally bleached to lighten its natural gray-brown color and to improve its gluten quality.

The most common bleaching agents in US flours are peroxides, chlorine compounds, azodicarbonamide and potassium bromate. The addition of any of them to flour is prohibited in Europe and elsewhere, and in some cases carries criminal penalties.

We recommend using unbleached flour whenever possible.

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