ENTIRE WHEAT FLOUR. 65 



wheats resulted in flours relatively low in ash and protein and 

 rich in starch and allied carbohydrates. Flour with no more 

 than 8 per cent protein and .3 per cent ash were not uncommon. 

 It was this kind of flour that led Liebig to recommend a return 

 to wheat meal and gave Graham the "physiological basis" of his 

 crusade in favor of bread made from unbolted wheat meal. De- 

 spite the agitation of this important question, the use of fine flour 

 did not diminish and the results of investigations indicated, on 

 even the part of the poorer classes, an almost invariable prefer- 

 ence for white bread. This was particularly the case in the 

 cities, and was at first attributed to perverted taste and classed 

 along with the desire for alcohol, and other abnormal appetites. 

 Investigations by Lawes and Gilbert* showed that this preference 

 was based upon a real difference in nutritive quality, and that 

 while graham bread actually carried more protein and ash than 

 white bread, it passed through the intestines rapidly "before the 

 system has extracted from it as much nutritive matter as it ought 

 to yield." This increased peristaltic action, resulting in lowered 

 digestibility of the bread, was attributed by Lawes and Gilbert 

 to the mechanical action of the bran upon the lining of the in- 

 testine. This seemed a reasonable hypothesis and some rather 

 inefficient attempts were made to manufacture a flour in which 

 the bran should be reduced to the fineness of flour. Before 

 much was accomplished in this direction, the method of milling 

 was revolutionized by the introduction of the Hungarian or 

 continuous reduction process. Up to this time the grain had 

 been ground and the milling products separated by a final sifting. 

 The new process passes the wheat through successive sets of roll- 

 ers or rolls set nearer and nearer together as the milling proceeds. 

 The flour from each set of rolls is removed by sifting and the un- 

 reduced portions are passed on to another set. While modern 

 flour mills differ from each other in details, they are all essen- 

 tially the same in that the bran is separated from the interior of 

 the grain and this interior is reduced to flour by repeated crush- 

 ing between rollers and numerous separations by means of bolt- 

 ing machines. The bran is also passed through successive rolls 

 and bolting machines, until it is as thoroughly cleaned from the 

 adhering flour as practicable for the kind of flour to be made, or 

 until the cost of reduction so nearly equals the value of the flour 



* Chemistry of Wheat and Flour. Lawes and Gilbert, 1S57. 



