PHYSIOLOGY: LANGWORTHY AND DEUEL 517 
Average digestibility of Graham flours milled by different methods 
KIND OF FLOUR 
NUMBER 
OF 
EXPERI- 
MENTS 
DIGESTII 
Pro- 
tein 
ILITY OF 
Fat 
ENTIRE 
Carbo- 
hydrate 
RATION 
Ash 
ESTIMATED 
DIGESTI- 
BILITY 
OF PROTEIN 
ALONE 
ESTIMATED 
DIGESTIBIL- 
ITY OF CAR- 
BOHYDRATE 
ALONE 
per cent 
per cetit 
per cent 
per cent 
per cent 
per cent 
Laboratory roller mill flour 
5 
72 A 
94: A 
96.0 
70.1 
70.7 
95.3 
Commercial roller mill flour 
5 
72.1 
95.6 
95.4 
67.6 
70.4 
93.8 
Steel-burr mill flour 
4 
79.2 
95.0 
96.1 
73.8 
78.5 
95.3 
Attrition mill flour 
3 
75.5 
92.9 
96.1 
69.7 
74.5 
95.4 
Stone-burr mill flour 
4 
79.2 
96.5 
96.6 
78.4 
78.2 
96.8 
The subjects in reports of their condition mentioned no discomfort. 
They did, however, speak of a somewhat laxative effect but noted no 
difference in this respect between the flours in which the bran was finely 
ground and those in which it was coarse. 
The amount of protein digested varied from about 70% in the roller 
mill flours in which the particles of bran were the largest to 78% in the 
stone-burr mill and steel-burr mill flours in which the bran particles 
were much finer. This is what we should expect for it has been shown 
that the bran protein^ is about 44% digested in the case of fine bran 
while it is only 28% digested in coarse bran. 
The coefficient of digestibility for carbohydrate varied from 93.4% in 
the coarse roller mill flour to 96.8% in the stone-burr mill flour. The 
estimated digestibility of the protein and carbohydrate represent the 
digestibility of the protein and carbohydrate of the flour alone after 
allowance has been made for the undigested residues of the accessory 
food. Possibly because of the kind of wheat used, the figures for pro- 
tein are somewhat lower than corresponding figures in other digestion 
experiments on 100% flour. Nevertheless, since those here studied are 
all from the same lot of wheat they are directly comparable with one 
another. The finer the particles, the more completely the protein was 
absorbed while the absorption of carbohydrate varied only slightly. 
In conclusion, it is fairly safe to say that the finer a bran-containing 
flour is ground, the more completely it is utilized by the human body. 
» Washington, U. S. Dept. Agric. Bull, No. 751, 1919, (pp. 20). 
2 Unpublished experiments. 
sLapicque, L., and Liacre, A., C. R. Sac. Biol, Paris, 81, 1918, No. 5, (pp. 217-220). 
