COMPARISON OF AMERICAN" WHEATS. 



25 



The average protein content of the wheat and of the straight flour 

 is compared in Table VI. With all three classes the protein in the 

 flour averages about 1 per cent less than in the wheat. 



Table VI. 



-Average crude-protein content of three classes of wheat and of the 

 straight flour made therefrom. 



Class of wheat. 



Number 



of 

 samples. 



Crude protein (per 



cent). 



Wheat. 



Straight 

 flour. 





215 

 323 



394 



10.6 

 12.1 

 12.9 



9.6 





11.2 





11.9 









932 



11.9 



10.9 







WATER ABSORPTION OF FLOUR. 



The importance of the water-absorbing power of flour in its rela- 

 tion to bread-making quality has been mentioned. Figure 20 will 

 emphasize what has been said of the connection of water absorption 

 with the weight of the baked loaf. It will be observed that as the 

 absorptive power increases there is a proportional increase in the 

 weight of the loaf, due to the water retained in the bread during 

 baking. That under average conditions the proportion of absorbed 

 water retained remains practically constant is also shown diagram- 

 matically in figure 20. 



In figure 21 a comparison is made of the flour from the five classes 

 of wheat under discussion, and it will be observed that the flour from 

 the soft white wheat has the lowest average absorption, while the soft 

 red winter wheat comes second. The hard wheat classes, including 

 the durum, do not show any very great differences, although the hard 

 red winter wheat averages slightly lower than the other two classes. 

 The extreme range in water absorption is narrowest in the soft wheat 

 and widest in the durums. There would seem to be a fairly close 

 connection between the gluten content or crude protein and the ab- 

 sorptive power of flour, as will be seen by comparing figure 21 with 

 figure 18. 



SUMMARY. 



(1) Normal, plump, dry, and sound wheat of all classes yields 

 approximately the same percentage of flour. Over 80 per cent of 

 the samples of each of the three classes of the more common wheats, 

 soft and hard red winter and hard red spring, yielded between 67 

 and 75 per cent of flour. 



(2) There is a direct relation between milling yield and the mois- 

 ture content of wheat, and in a general way the yield varies inversely 



