45 



jrround rye bran and flour is not so completely absorbed as the flour 

 without the bi-an. A number of digestion experiments were made b}'' 

 him to determine the comparative digestibility of the diflerent kinds 

 and grades of rye flour. The experiments, which are of especial inter- 

 est in connection with a discussion of the efl'ect of the presence of bran 

 in the flour on the digestibility of bread, are summarized in the table 

 below. The data as originally published showed the percentage 

 amounts which escaped digestion, but in quoting the results the}- have 

 been recalculated to show the coefficients of digestibilit}^ so that they 

 may be more readily compared with those reported in this bulletin. 



Table 32. — Coefficients of digestibility of different kinds of rye bread. 



Kind of flour used for making bread. 



Fine light-colored rye flour 



Fine rye flour containing ii little bran 



Fine dark-colored rye flour containing considerable bran 



Rye graham flour mixed with a littlt tine flour 



Rye flour ground from entire grain 



Carbohy- 

 drates. 



Per cent. 

 98.34 

 95. 85 

 91.92 

 85. (H) 

 97.59 



From these tests and others made with the dititerent r3'e milling pro- 

 ducts the conclusion was drawn that adding the bran, even if flnely 

 ground, diminished digestibility and that bran can not be so prepared 

 b}' grinding that it is suited for human food. 



Pannwitz." in a study of the nutritive value of diflerent sorts of 

 arm}' bread, also reported at length by Plagge and Le))bin,'' took into 

 account the efl'ect of the presence of different proportions of bran on 

 digestibility. In these experiments the diet consisted of bread alone. 

 The following table summarizes the principal results and, as before, 

 the data have been recalculated to show the coefficients of digesti- 

 bility instead of the amounts which escaped digestion: 



Table 33. — Coefficients of digestibility of different sorts of bread. 



Kind of flour used for making bread. 



Decorticated rye flour with 15 per cent bran removed 



Coarse decorticated rye flour with 7.5 per cent bran removed 



Coar.se decorticated rye Hour with 15 per cent bran removed 



Finely ground decorticated rye flour with 10.84 percent bran removed .. 

 Finely ground undecorticated rye flour with 12.68 per cent bran removed 

 Finely ground undecorticated rye flour with 25 percent bran removed... 



Fine wheat flour with 30 per cent bran removed 



Finely ground bran 



Coarsely ground rye. no bran removed — ' pumpernickel " 



Entire-fye bread made from crushed grain without previous grinding . . . 



The conclusion was reached that the value of flour depended upon 

 the amount of bran removed, and that bran, even if flnely ground, was 

 not suitable for human food. In the author's opinion, decortication 

 before grinding is not necessary provided 15 to 25 per cent of the bran 



alnaug. Diss., Univ. Berlin, 189.S. '' ViToffentl. Mil. Sanitiitsw., 1897, No. 12. 



