5.1.2: Flour Terms and Treatments
Flour Terms and Treatments
In addition to types of flour, you may come across various other terms when purchasing flour. These include some terms that refer to the processing and treatment of the flour, and others outlining some of the additives that may be added during the milling and refining process.
Bleached
Bleaching and maturing agents are added to whiten and improve the baking quality quickly, making it possible to market the freshest flour. Even fine wheat flours vary in color from yellow to cream when freshly milled. At this stage, the flour produces doughs that are usually sticky and do not handle well. Flour improves with age under proper storage conditions for up to one year, both in color and quality.
Because storing flour is expensive, toward the close of the 19th century, millers began to treat freshly milled flour with oxidizing agents to bleach it and give it the handling characteristics of naturally aged flour. Under the category of maturing agents are included materials such as chlorine dioxide, chlorine gas plus a small amount of nitrosyl chloride, ammonium persulfate, and ascorbic acid. No change occurs in the nutritional value of the flour when these agents are present.
There are two classes of material used to bleach flour. A common one, an organic peroxide, reacts with the yellow pigment only and has no effect on gluten quality. Chlorine dioxide, the most widely used agent in North America, neutralizes the yellow pigment and improves the gluten quality. It does, however, destroy the tocopherols (vitamin E complex).
Enriched
Replacing naturally occurring nutrients that may have been lost during the milling process. Iron and three of the most necessary B vitamins (thiamin, riboflavin, and niacin), which are partially removed during milling, are returned to white flour by a process known as enrichment. No change occurs in taste, color, texture, baking quality, or caloric value of the flour.
Fortified
Adding a nutrient that was not present before or adding in larger quantities. Folic acid (folate) is added to enriched grains in an effort to prevent neural tube defects in children. Another example is Vitamin D fortification which we discussed previously in the milk chapter.
Pre-sifted
During the milling process, flour is sifted many times through micro-fine silk. This procedure is known as pre-sifting. The mesh size used for sifting varies from flour to flour. There are more holes per square inch for cake flour than, for example, bread flour, so a cup of cake flour has significantly more minute particles than a cup of bread flour, is liable to be denser, and weighs slightly more. Sifted flour yields more volume in baked bread than unsifted flour, simply because of the increased volume of air.
Flour Additives
A number of additives may be found in commercial flours, from agents used as dough conditioners to others that aid in the fermentation process. Why use so many additives? Many of these products are complementary – that is, they work more effectively together and the end product is as close to “ideal” as possible. Nevertheless, in some countries the number of additives allowed in flour is limited. For instance, in Germany, ascorbic acid remains the only permitted additive.
Some of the additives that are commonly added to flour include those described below.
Bromate
Until the early 1990s, bromate was added to flour because it greatly sped up the oxidation or aging of flour. In the United States, bromate is allowed in some states but banned in others (e.g., California).
Azodicarbonamide (ADA)
Approved in the United States since 1962. ADA is a fast-acting flour treatment resulting in a cohesive, dry dough that tolerates high water absorption. It is not a bleach, but because it helps produce bread with a finer texture it gives an apparently whiter crumb. It does not destroy any vitamins in the dough.
Bakers who want to know if their flours contain ADA or other chemical additives can request this information from their flour suppliers.
L-Cysteine
An amino acid, L-cysteine speeds up reactions within the dough, thus reducing or almost eliminating bulk fermentation time. In effect, it gives the baker a “no-time” dough. It improves dough elasticity and gas retention.
Ascorbic Acid
Ascorbic acid was first used as a bread improver in 1932, after it was noticed that old lemon juice added to dough gave better results because it improved gas retention and loaf volume. Essentially vitamin C (ascorbic acid) has the advantage of being safe even if too much is added to the dough, as the heat of baking destroys the vitamin component. The addition of ascorbic acid consistent with artisan bread requirements is now routine for certain flours milled in North America.
Calcium Peroxide
Calcium peroxide (not to be confused with the peroxide used for bleaching flour) is another dough-maturing agent.
Glycerides
Glycerides are multi-purpose additives used in both cake mixes and yeast doughs. They are also known as surfactants, which is a contraction for “surface-acting agents.” In bread doughs, the main function of glycerides is as a crumb-softening agent, thus retarding bread staling. Glycerides also have some dough-strengthening properties.
Sodium Stearoyl Lactylate
Approved for use in the United States since 1961, this additive improves gas retention, shortens proofing time, increases loaf volume, and works as an anti-staling agent.