Pro Tip: Understanding what contributes to the functionality of flour can help bakers optimize that functionality.
In this Pro Tip, I’ll be talking about what contributes to the functionality of bread flour.
1. Starch makes up more than 65% of flour. It consists mainly of amylopectin and amylose. Amylose is mainly responsible for the staling mechanism in bread when it be-comes rigid. Therefore, the enzyme alpha amylase acts on amylose to shorten its length. This prevents it from becoming rigid after it is baked, extending the shelf life of the bread. Amylopectin and amylose are packed into two forms of starches in the flour: native, which is intact starch granules, and damaged starch, which are starch granules that have been broken in the milling process. Damaged starch is an important aspect of flour at about 10%. It affects water absorption. Therefore, a percentage or two increase in dam-aged starch can affect the feel of your dough.
2. Pentosans are composed of five carbon sugars and are usually at a level of 2-3% in wheat flour. Pentosans can absorb four times their weight in water. Therefore, they influence water absorption and the viscoelasticity of bread dough. Because they improve water absorption, more water is held in the system, delaying staling. As a result, pentosans improve shelf life. On the other hand, excess pentosans can cause a slack dough, as in the case of rye flour, which typically contains 10% pentosans.
3. Gluten is the most functional components of flour at 7-15%. It consists of both gluten and water-soluble proteins, albumin, and globulin. Gluten provides the gas retention and viscoelasticity of wheat doughs. While albumin and globulin, present at 2-3% of the flour weight, affect water absorption, mixing and to a certain extent, loaf volume and texture.
4. Lipids are naturally present in the flour and have the least effect on flour quality and functionality. At about 2% of the flour, these include non-polar lipids and phospholipids, which can act similarly to emulsifiers. Lipids allow for the mobility of gluten and starch molecules during the bake, enhancing oven spring and shelf life.
5. Ash is about 0.5% of the flour and is an indication of how well the flour milling process has removed the bran. The higher the ash, the poorer the baking quality. Ash doesn’t affect water absorption or mixing, but it does disrupt gluten formation. Too much ash would affect dough volume and the color of the final product.
6. Enzymes occur naturally when wheat kernels sprout during the harvesting process. It sometimes cannot be controlled, but millers try to dilute the effect of sprout damage by blending it with other non-sprouted kernels. Anything below 250 seconds of the falling number test would indicate excessive enzymes. This would result in a slack dough that is difficult to process with a compromised bread volume.
To learn how to analyze these flour components, tune into my next Pro Tip.