In the average composition of wheaten bread nitrogen exists in the proportion of 1 part to 21 of carbon (Yeo). Besides the deficiency in nitrogen, there is but a trace of fat in refined flour, a trace of acid, and little mineral matter.

The following table from the U. S. Department of Agriculture Bulletin No. 67, 1899, gives the percentage of:

Proteids In Wheat Flour

Albumin........................................... 0.3 per cent.

Globulin............................................9 "

Proteose body........................................2 "

Gliadin............................................ 6.8

Glutenin............................................ 4.5 "

Total.......................................... 12.7

The best wheaten flour for wholesome bread should be of a slight yellowish-white tinge, and not too fine. The colour fades as the flour becomes dry.

Yellow flour is sweeter and more nutritious than white pastry flour, although it makes a darker bread. The flour contains 10 to 11 per cent of gluten. Such flour when mixed with water should form a dough which is both coherent and ductile. These properties are due to the gluten which it contains.

Bread made from good flour should be porous, but not filled with large holes, and should have the proper consistence and firmness to cut well in thin slices. Wheaten flour contains much less crude gluten after thorough baking, for in the process of strongly heating flours containing nitrogenous material, the proteid as well as the starch becomes more soluble in water (Leeds).

Heavy, sodden bread has been insufficiently fermented.

Tough, moist, imperfectly baked, or hot bread is liable to excite further fermentation in the stomach, causing heartburn and other symptoms of dyspepsia. The digestibility of such bread is promoted by heating it to drive off the moisture, and by spreading it well with butter to prevent it from agglutinating in the stomach.

Water continues to evaporate from hot fresh bread, and such bread should not be covered tightly, or else it becomes sodden.

Stale bread and dry toast are both more digestible than fresh bread. In stale bread water is evaporated to a great extent, so that the bread becomes friable and is more readily masticated and mingled with digestive fluids. The fact that stale bread on being warmed over becomes softer is accounted for on the hypothesis that in drying the water has not all been evaporated, but that some of it has combined with the flour, forming a new compound, which is dissociated by the further application of heat (Yeo).

In toasting, the digestibility of bread is still further promoted by additional heat, and the superficial layers are browned and altered in flavour, acquiring a taste somewhat similar to caramel. Water is evaporated, and a slice, if sufficiently thin, bakes dry and crisp throughout, but if thick, the outer layers are scorched while the mass within may become even softer than before toasting.

Buttered dry toast is a digestible form of invalid food, for if the butter be spread thin while the toast is quite hot it penetrates to the interior, and both fat droplets and starch crumbs mutually protect each other from cohering in large masses. The butter, moreover, enables one to eat more bread in this form. The same is true of milk toast, and this furnishes in addition a means of giving considerable milk to patients who are unwilling to drink it.