The average composition of flour is as follows:
11.4 per cent
1.0 75.1 1610 Cal. per pound
100-Calorie portion 28 grains (1 ounce)
The protein occurs in the form of gluten, which has the property of stretching and expanding, and which makes the framework of the loaf of bread, since it retains the air and carbon dioxide, and hardens when baked. The protein of oats and corn lacks this property, and therefore oatmeal and corn meal give a very different type of bread. Rye flour contains gluten, and the rye loaf therefore resembles the wheat loaf. Wheat and flour differ largely on account of the difference in the amount of gluten, and the gluten itself varies in quality with the variety of wheat.
Courtesy of Utah Agricultural College.
Fig. 52. - Experiment illustrating the effect of the kind of wheat upon the size of the loaf.
Figure 52 shows the result of an experiment with flour made from different kinds of wheat, all the other factors in the bread making being identical. This effect of the difference in the composition of the flour is very striking. Again, the same variety of wheat will differ from season to season, and the time of planting, also, affects the quality of the grain. The time of planting and reaping gives us two classes of wheat and flour, the winter and spring. Winter wheat is sown in the fall and obtains its first growth before winter, living through the winter in those latitudes where the climate is sufficiently mild, being harvested in early summer. Spring wheat is sown in the spring and harvested late and it is the wheat of the great flour-producing state, Minnesota. The difference in the composition of the two wheats is shown in this table.1
Spring varieties . . .
Winter varieties . . .
Note that the spring wheat contains more protein and therefore more gluten. The flour from spring wheat is creamy in color, granular to the touch, has more gluten, and is known as a strong flour. Flour from winter wheat is somewhat whiter in color and smoother to the touch, feeling more like cornstarch, and if a portion is squeezed in the hand, it retains the imprint of the fingers. It has less gluten, more starch, and is known as a soft flour. This type of flour is sometimes called "pastry flour," the smaller percentage of gluten making it more desirable for pastry or cake than the stronger flour.
Flour manufacturers and bakers are constantly experimenting to find the best possible varieties and combinations of varieties for bread flour. Some difference of opinion exists, but a combination of winter and spring wheat in flour is considered the best for bread by some authorities.
1 U. S. Department of Agriculture, Farmers' Bulletin 389, p. 16.
We must learn to like a creamy color in bread, for this means the presence of more gluten. To summarize : a good bread flour contains a large percentage of gluten, is creamy in color, and granular to the touch.