Quality, like beauty, is in the eye of the beholder. One cannot discuss quality without defining quality for what purpose. This is particularly true for biological materials such as wheat flour. A good quality flour to produce white pan bread is not necessarily good to produce a sugar-snap cookie. Yet to the layman or casual observer all wheat flours look alike.
There are large differences found between bread, cake, pastry, and cookie flours and also within each of those types. Taking bread flour as an example, good quality flour to produce white pan bread is certainly different than that to produce bagels or a hearth bread. It is also true that a good quality bread flour for line 1 in plant A is not necessarily a good quality flour for line 2 in that same plant. Differences in the equipment making up the line or even the physical layout of the line will demand that the flour be different to perform at its optimum. The same would certainly hold for different plants. The variation can be true even if the plants contain the same equipment and have essentially the same layout. The rheological properties of dough are greatly affected by dough temperature. Thus, a plant in Miami may need a different flour than a similar plant in Minneapolis or Chicago. It is also true that the relative humidity of the location is important as it controls how much water is lost from the doughs during processing.
Given the great diversity in wheat flour quality, how can these differences be measured? The easiest thing would be to use a physical dough test. But as discussed above they will not tell the flour’s baking quality. This leads to the conclusion that to determine the quality of the flour we must produce the product for which the flour was intended. Thus, to determine the bread baking quality of a flour we must bake bread.
There is no doubt that test baking is much better than any physical dough test in evaluating wheat flour quality. Using a reasonable formula and procedure, the flours’ baking properties can be determined. However, even test baking results are not infallible. Why doesn’t test baking give all the answers? One item that is often mentioned is the size of the loaf. Many test baking procedures use a small loaf size, for example pup loaves that are made from 100 g of flour. In actual fact, the size of the loaf is of little importance. Because the dough produced from 100 g of flour, about 160 g, can be handled much more easily and reproducible than a larger mass of dough, the reproducibility with pup loaves is better than for bread made from larger doughs. Two more important variables than loaf size are temperature and time.
A small dough mixed in a pup loaf mixer will remain at a constant temperature throughout mixing. The large aluminum bowl dissipates any heat produced. On the other hand, the temperature will rise considerably in a large mass of dough mixed in a commercial mixer. Thus, the dough out of the mixer will have a different temperature. All bakers know the temperature of the dough out of the mixer is an important variable. Another factor to consider is that test bakeries are temperature controlled by bakeries are not. In addition, with pup loaf baking each dough is mixed separately and processed on a rigid time schedule. In commercial production the large mass of dough is mixed and it may take some time for all of this dough to be processed. Thus, samples taken at the beginning of the dough will have a different processing time than those at the end of the dough.