50 



Summarizing briefly the results of the fifteen experiments with soft- 

 wheat flours, it appears that while the graham and entire-wheat flours 

 contain a larger amount of protein and energy, the lower degree of 

 digestibility of these flours, due to the coarser granulation, renders 

 available to the body a smaller proportion of total nutrients as well as 

 energ}' than in the case of straight-grade flours, ground from the same 

 wheat, which are more finely granulated and more completely digested. 

 This is entirely in accord with the results obtained in the investiga- 

 tions with hard-wheat flours more exhaustively milled. 



As was the case in the tests with bread from dift'erent grades of hard- 

 wheat flour, no variations were observed in the metabolism of nitrogen 

 which could be atti'ibuted to the use of the difl'erent sorts of flour 

 constituting the principal part of the diet. 



GENERAL SUMMARY OF RESULTS AND CONCLUSIONS. 



The experiments with hard wheat milling products reported in the 

 present bulletin are the latest of a fairly extended series which has 

 given uniform results. The experiments with soft wheat are the first 

 of a proposed series and are less numerous than those made with hard 

 wheat. The results already obtained, however, are in accord with 

 what has been learned regarding the milling products of hard wheat. 

 Some general deductions from the experiments as a whole seem 

 warranted. 



As shown by analj^sis the patent flour, ground from the hard and 

 soft wheats studied, had a somewhat lower protein content than the 

 graham flour and entire-wheat flour ground from the same wheats, but 

 according to the results of digestion experiments with the difl'erent 

 grades of flour from these wheats, the proportion of digestible pro- 

 tein and the available energy in the patent flour was larger than in 

 the coarser grades. The lower digestibility of the protein in the latter 

 is, it appears, due to the fact that in these grades a considerable por- 

 tion of this constituent is contained in the coarser particles (bran) and 

 thus escapes digestion as it is not acted upon b}- the digestive juices. 

 Thus, while there may be actually more protein in a given amount of 

 graham or entire-wheat flour than in an equal amount of patent flour 

 ground from the same wheat, the Ijody secures less of the protein and 

 energy from the coarse flour than it does from the tine, since although 

 the retention of the bran and germ increases the percentage of pro- 

 tein it decreases the dio-estibilitv. Bv digestiljilitv is meant the dif- 

 ference between the amounts of the several nutrients consumed and 

 the amounts excreted in the feces. No attempt was made to stud}' the 

 ease or rapidity of digestion of the difl'erent sorts of flour. When the 

 digestibility of difl'erent grades of patent flour was studied it was 

 found that there was no marked difl'erence between standard patent 



