Many bakers are interested in creative baking but are confused: which flours may I interchange and what adjustments must then be made. Sorting the misconceptions from the technology can be discouraging as trial efforts fail or fall short of expectations. This article will define parameters for substituting specialty flours in formulae and recipes already in use.
Flour, the main ingredient in bread, is most often milled from wheat, but many other grains and vegetables can be made into flours that can be used in bread and other baked products. Rye is second in popularity as a grain for bread flour. Other grains used for flour include soy, corn, barley and oats. Flours are also made from buckwheat, which is a cousin of rhubarb, and from starchy vegetables, such as potatoes. Each of these specialty flours has its own requirements as to the proportions of other ingredients used in the bread, kneading, rising and baking times and temperatures. Understanding the basic properties of these flours will enable the baker to achieve good results as well as to troubleshoot problems.
While the form and shape of each grain varies, cross sections show them to be similar. The exterior envelope consists of several layers of cellulose, which h together make the bran. At the base of the grain near the stem is the small germ, which is the embryo of the future plant. It is rich in oil, protein, iron and vitamins B and E and has a nutty taste. The mass of the grain is the endosperm, which nourishes the germ. It is primarily starch but also contains gluten-producing protein and minerals such as phosphorus, magnesium, iron, zinc, copper, and manganese. Regular white wheat flour comes from the endosperm. The germ, which spoils easily, and the bran, which is a non-nutritive fiber, are removed by the mills that produce white flour.
Specialty flours, both fine and coarse, can be used alone or mixed with white wheat flour for variety in flavor and texture. When used alone, they almost always produce flat, dense breads. For light-textured, well-risen breads, they must be combined with wheat flour, which provides effective gluten-forming protein as well as abundant starch to nourish the yeast. Wheat flour is favored fro bread baking precisely because strong gluten is found only in wheat; the gluten in other grains does not have the elastic qualities of wheat gluten, which help the dough to obtain the characteristic lightness normally associated with leavened bread.
During kneading, the gluten develops and forms a network of strands, which imprisons the carbon dioxide given off by the yeast during fermentation (rising). The filaments of gluten stretch to hold the gas, and the meshing of these pockets of gas constitutes the final texture of the bread. During baking, the gluten solidifies to produce a firm but light texture.
Ample fermentation time is necessary to break down the starches (which are complex sugars) into simple sugars. These sugars are not only more palatable than starches; they also color the baked bread. During fermentation, the starch and sugar feed the yeast so it releases sufficient carbon dioxide and thus enables the dough to expand.
Only two specialty flours are made from wheat and thus contain this gluten-forming protein: whole wheat and gluten flours. Rye flour and triticale flour, a hybrid of rye and wheat, have gluten but of insufficient strength to raise loaves. The rest have only traces of gluten, or in the case of soy flour, which is made from a bean, none at all.
The following recommendations for using specialty flours are based on the classic white-bread method, which yields a light, well-risen loaf, creamy in color, with a crisp crust and the naturally sweet flavor of the wheat grain. This loaf, based on yeast, requires kneading to thoroughly develop the gluten, a long fermentation (one and a half hours is optimal), and thorough baking in a hot oven. Flour, water, salt, and yeast are the only necessary components in this type of bread. Sugars and fats are recommended when needed only to counteract a deficiency in particular flour. Sugar accelerates yeast activity, but too much inhibits it and will make the bread overly sweet. Too much fat can coat the gluten strands making them slippery and retarding the development of the network that traps the carbon dioxide.
This kind of dough can be baked in a pan, though the following recommendations are designed to yield a dough with strong enough gluten to support an unstructured hearth bake, producing a crisper crust.
Whole wheat or graham flour: whole wheat contains all the elements of the wheat grain, including the germ and the bran. It is, thus, very nutritious. However, the strong nutty flavor of the germ masks the natural, subtle sweetness of the wheat endosperm. The oil in the bran makes for a bread heavier than a white loaf, although it does rise. The crumb is coarse and mealy, and the crust is chewy. A lighter loaf is achieved by replacing 20% of the whole-wheat flour with white flour to increase the gluten content. Whole wheat bread requires a shorter mixing time and a shorter rise than dough made with only white flour. Due to the oiliness of the germ, the bread must be baked more slowly than white bread, in an oven 25° Fahrenheit cooler. The oils also can turn rancid once exposed to air; therefore, whole-wheat flour should be used quickly or stored in the refrigerator. When the whole-wheat kernel is very finely powdered, the product is often called graham flour and the bran is less discernible in the finished loaf.
Gluten flour: high in protein and low in starch, gluten flour is most often used for special diets. It is made from wheat endosperm specially treated to remove starch. Bread made with it is dry, fine-grained, and somewhat tough. The crust is pale. Doughs made of flours low in gluten are improved by replacing five to ten percent of the flour with gluten four. Alternatively, gluten flour can be used in a 2:1 ratio with wheat flour. Decrease normal kneading time by 25 % to avoid overdeveloping the gluten. The first fermentation will be longer and the second shorten than usual. A somewhat hotter over (25° Fahrenheit) will help color the crust. Sugars, milk products, and fat are often not incorporated since bread made with this hard-to-find flour is usually for those on special diets. Gluten flour keeps very well in a dry area. The loaf, being dry, goes stale rather quickly.
Medium rye flour: after wheat flour, rye flour is the most suitable for bread. Light or white rye flour is weak in flavor, but the taste of medium rye is full and slightly sour and traditionally complements oysters and ham. The crust is typically chewy and dark, and the crumb is moist, compact, and a crumbly with an affinity for nuts and seeds. It can be used straight or mixed with wheat flour, although pure rye flour yields a loaf that rises little. Containing rubbery substances that prevent the gluten from developing, rye dough is sticky. Because the gluten is fragile, machine kneading must be done on low speed, and shaping should be done delicately. A mixture of 40% wheat flour with 60 % medium-rye flour will yield a loaf that rises, is therefore not unpleasantly heavy, and still maintains the characteristic density and flavor of rye. The best results are obtained by adding the rye flour to a base of white dough that has already fermented for 30 minutes. This helps strengthen and stabilize the fragile gluten. A few drops of vinegar will enhance the characteristic flavor of rye. Steam will help develop the typical chewy crust. The baking should be at a lower temperature than that for wheat breads, and the loaves must be well baked to eliminate any gumminess. They are often aged 24 hours before eating to improve their texture. Rye breads keep well. Covered in plastic and refrigerated, they maintain their supple crumb without great alteration in consistency for up to one week.
Dark rye and pumpernickel: dark-rye bread has a full and pronounced sour taste. Its dark crust is coarse and grainy, and it has a dense, compact, moist, crumbly texture. Unlike medium-rye flour, in which bran is only sometimes included, these flours (both also made from rye) always contain the bran of the grain. Pumpernickel flour contains a higher proportion of the bran than does dark-rye flour and is often combined with whole-wheat flour. These flours can replace up to 50% of the wheat flour, but will not yield a light loaf. There will be practically no perceptible rise if a higher proportion is used.
Triticale: triticale is a man-made hybrid of wheat and rye that occurs in nature only as a sterile grain. It tastes somewhat like rye and has the natural, light sweetness of wheat flour. Its crust is pale and soft textured, and its crumb light and grainy. While its protein content is high, its gluten is not effective and needs the addition of wheat flour to produce a light loaf. One-third triticale flour produces the most pleasing loaf, although up to 50 percent can be used. As in rye breads, gentle handling of the dough is required.
Barley flour: An ancient grain that has been cultivated for at least 4,000 years, hardy barley grows in nearly any climate. Barley is appreciated for the nutty, malty, earthy flavor and moist, chewy interior it gives to white bread. It, too, is poor in gluten and produces a flat, gray bread if not mixed with wheat flour, hence the derogatory French expression mauvais comme le pain du sarrasin "as bad as barley bread." Barley flour should not exceed 10 percent of the total flour, and even this amount yields a loaf that is rather too sticky. Rising is quick, and, as with most specialty breads, since the plastic qualities of the dough are diminished, the bread is less light and not as well risen as wheat-flour bread. It goes stale quickly. Barley bread should be baked slowly at a lower than usual temperature.
Buckwheat flour: Buckwheat is a member of the rhubarb family and not a grain. It is best known as a component of Russian blinis, Breton galettes, and American breakfast cereal. The flour produces a loaf with a hard crust and a fine, moist crumb. As nourishing as wheat and agreeable in flavor, buckwheat, nevertheless, is another flour with poor gluten. For best results, replace up to 30 % of the wheat flour with buckwheat flour. Although up to 50% can be used, this percentage will make bread that is extremely heavy, dark, and compact. Buckwheat dough reacts in the same way as rye. Adding the buckwheat flour to a base of white-flour dough that has fermented half an hour will strengthen the gluten. Do not allow to rise too long.
Soya flour: used for centuries in the Orient, soybeans are now recognized in the western world as a valuable nutrient due to their high protein content. Soya flour is made from lightly toasted soybeans, soy flour from the raw beans. Soya flour has a more agreeable flavor. It produces a loaf with a sweet, musty taste, a chewy and golden crust, and a moist, fine-grained, tender crumb. Full-fat soya flour is 20% fat. The flour can also be purchased with the fat partially or fully extracted. Its nutritive value is higher when it contains the fat. Having no gluten at all, it may replace only up to 20% of the total quantity of wheat in bread. Bread with soya flour is slightly heavy. It browns quickly and therefore needs a lower than usual oven temperature. Breads made with soya flour keep well.
Potato flour: much admired for its sweetness, potato flour mixed with wheat flour gives excellent results, producing a loaf with a crisp crust and a flavorful crumb. Although found in a tuber, the starch is the same as that found in grains. It is rich in vitamin C, thiamine, iron and potassium. It is costly to produce and usually is used only in the absence of other flours. Potato flour can be used for up to 20% of the flour in bread. Used in quantities over 20%, potato flour makes the dough difficult to shape. Dough made with potato flour will tend to be more difficult to moisten when mixing with the liquid then that made with all-wheat flour, but it is easy to knead. The potato activates fermentation, so the rise will be quicker than with a straight wheat bread. Its baking time is significantly less. Bread including potato flour is moist and keeps well.
White-rice Flour: Rice produces a sweet but bland loaf, with a pale, delicate crust and a cream-colored crumb that is fine-grained and rather dry. It is richer in starch than wheat flour, but has poorer gluten that does not stretch. Therefore, it cannot be used alone in bread making but can replace 20% of the wheat flour and yield a risen loaf. Rice flour will absorb more liquid that wheat flour, though it absorbs it slowly and thus requires a longer mixing time. The oven temperature should be the same as for a wheat loaf, but it will not brown as well.
Brown-rice flour: Brown-rice flour contains the germ and the bran of the grain. Replacing wheat in the same proportions as white-rice flour, it yields a darker loaf that is quite heavy with a nutty, rich flavor. The oil in the germ will turn rancid quickly so the flour should be used rapidly or stored in the refrigerator.
Oat flour: oats contain the same quantity of starch as wheat, but are richer in fats and minerals. Oat flour is difficult to mill, and its gluten is very poor for bread making, but oats have a nice sweet, earthy taste. Fifteen percent oat flour will impart a hearty flavor to the loaf. The dough should be fairly stiff and requires thorough kneading. It will rise slowly. Gluten flour might be added for extra lightness. Loaves should be baked with a pan of water on the floor of the oven to produce steam. Oats contain a natural antioxidant and therefore produce a loaf that keeps well.
Corn flour: corn produces a cream-colored flour, and although it is sometimes labeled meal, it is more finely ground than cornmeal. It has a sweet flavor, is rich in oils, and is a good source of vitamin A. Corn does not contain any protein capable of producing gluten, and so it produces a sticky dough that rises poorly. Corn flour normally is used for batter type, non-yeast breads but can nevertheless replace up to 20% of wheat flour in yeasted breads. Bread made with corn flour has a pale, thick crust and a crumb that is yellow, crunchy and crumbly. It demands no special preparation or baking variations on the basic white-loaf method. Corn flour for use in bread should not be confused with cornstarch used for thickening.
Millet flour: a valuable source of protein, millet is a staple grain in some parts of the work. It produces a loaf with a smooth and chewy crust and a fine-grained interior. It tastes nut-like and is lightly sweet. It can replace up to 20% of the wheat flour using the usual method.
Bran: bran is the envelope of the wheat grain; it is not a flour and will not react with yeast. It current popularity leads us to include it in bread to provide roughage for those whose diets are poor in vegetable fibers. It has an earthy taste and gives a crumbly texture to bread. A medium bran flake is the most compatible with wheat flour and can be used to replace 20% of the flour. The bran cuts the gluten development making for a dense loaf. More liquid can be incorporated into a bran dough than a straight wheat dough. One-half ounce butter or oil per pound of flour should be added to this dough when mixing to obtain a loaf that is not overly crumbly. The first fermentation should be slightly longer, and the second fermentation shorter than usual. The moister bran loaf will require slow baking in fairly low oven heat.