DIGESTIBILITY. The digestibility of bread is a very important matter, which has been often studied by methods of artificial digestion and by experiments with man. Among the best known of the latter are those conducted by Meyer and Voit, of Munich. Four kinds of bread were used: ( 1) Rye bread, raised with a leavening powder; (2) bread made from a mixture of rye and wheat flours, and raised with yeast; (3) fine white bread raised with yeast, and (4) coarse whole wheat bread, which the Germans call 'pumper nickel,' raised with yeast. The third of these— fine white brimd—yielded the highest percentage of digestible nutrients; next came the wheat and rye bread; then the bread raised with leavening powder, and last. the pumpernickel, which is too coarse to he justly compared with whole-wheat bread such as is made in the United States, The fine white bread was the lightest : next to it stood the rye and Avheat, and next, that raised with the powder; the same order these breads, took with regard to digestibility. These experi ments show, not so much the comparative value of different flours, as that the digestibility of bread depends largely upon its lightness.
A number of experiments have been recently made. especially by Snyd(kr. and by Woods and Merrill, on the digestibility of bread from differ ent grades of flour ground from the same lot of wheat. The average result of a number of such experiments follows: According to the chemical analysis of graham, entire-wheat, and standard patent flours milled from the same lot of hard Scotch Fife spring wheat, the graham flour contained the highest and the patent flour the lowest percentage of total protein. (See WHEAT.) But according to the results of digestion experiments with these flours the proportions of digestible or available protein and available energy in the patent flour were larger than in either the entire-wheat or the graham flour. The lower digestibility of the pro tein of the latter is due to the fact that in both these flours a considerable portion of this eon stituent is contained in the coarser particles (bran), and so resists the action of the digestive juices and escapes digestion. Thus, while there
actually may be more protein in a given amount of graham or entire-wheat flour than in the same weight of patent dour from the same wheat, the body obtains less of the protein and energy from the coarse flour than it does from the fine, be cause. although the including of the bran and germ increases the percentage of protein, it de creases its digestibility.
The digestibility of first and second patent flours, as shown by experiments made at the same time as those noted above, was not appre ciably different from that of standard patent flour. The degree of digestibility of all of these flours is high. due largely to their mechanical condition; that is, to the fact that they are finely ground.
Judged both by composition and digestibility, good bread is a wholesome. useful food. As com pared with most meats and vegetables, bread has practically no waste, and is quite completely di gested. It is too poor in protein to be fittingly used alone, but when used with due quantities of other foods, it is invaluable, and well deserves its title of 'the staff of life.' Statements of a popu lar nature are frequently met with on the un wholesomeness of hot bread. The fact that bread is hot has doubtless little to do with the matter. New bread, especially that from a large loaf, may be readily compressed into more or less solid masses, and it is possible that such bread would be much less finely masticated than crumbly, stale bread, and that. therefore, it might offer more resistance to the digestive juices of the stomach. Bowever, when such hot bread as rolls, biscuit, or other form in which the crust is very large in proportion to the crumb, is eaten. this objection has much less force. There is little difficulty in masticating the crust, and it is doubtless usually finely divided.