53 



GENERAL SUMMARY OF RESULTS AND CONCLUSIONS OF 

 EXPERIMENTS WITH BREAD. 



In eighteen digestion experiments with men it was found that white 

 (straight-grade) flour was more completely digested than either (xra- 

 ham or entire-wlieat flo:ir, and yielded a larger amount of digestible 

 nutrients and available energy. While Graham and entire-wheat 

 tiours contain more total protein and fat and have a higher heat of 

 combustion, they actually yield to the body, because of their lower 

 digestibility, smaller percentages of digestible nutrients and available 

 energy than the straight-grade flour. 



The same general differences in digestibility of the three grades 

 of flour have been noted in experiments with hard northwestern 

 spring wheats grown in Minnesota and Dakota, hard winter wheat 

 grown in Oklahoma, and soft winter wheats grown in Michigan, Indi- 

 ana, and Oregon. In tifty-four digestion trials with both hard spring 

 wheats and soft winter wheats in which six separate samples of wheat 

 have been milled so as to produce the three types of flour — Graham, 

 entire-wheat, and straight-grade — uniform results have been secured, 

 and in all of the comparative trials the largest amounts of available 

 nutrients and energy have been secured from the wdiite flour. 



In the three digestion trials in which flnel}^ pulverized bran was added 

 to white flour in the same proportion as is removed in milling, it was 

 found that the addition of the bran lowered the digestibility of the 

 flour so that a smaller amount of digestible nutrients and available 

 energy was obtained from the bran flour than from the white flour with 

 which the bran was mixed. The flour containing flnely pulverized bran 

 was more digestible than the coarsely grantdated Graham flour, ])ut 

 less digestible than the white flour. When bran was flnely pulverized 

 it failed to digest as completely as the white flour and, therefore, the 

 addition of the bran lowered the food value of the flour. 



In three digestion trials in which flnely pulverized wheat germ was 

 added to white flour in the same proportion as is removed in milling, 

 it was found that the addition of the germ did not materially change 

 the digestibility of the flour, and that the amount of total digestible 

 nutrients and available energy in the germ flour and the white flour 

 was about the same. There was no material gain in total digestible 

 nutrients by the addition of the germ to the white flour. The germ 

 flour produced a smaller sized, sweeter, but less porous loaf than the 

 white flour. Because of its fermentable character wheat germ is 

 excluded from white flour. 



As to pecuniary value, a larger amount of available nutrients and 

 energy can be procured at the usual prices for a given sum of money in 

 the form of white, that is, straight-grade, flour than of any other flour. 

 White flour contains the largest amount of available nutrients, and is 

 not only the most digestible, but at present average market prices is 



