11 



to prepare straight-grade, Graham, or entire-wheat tlours from a small 

 .sample of wheat. 



The Oregon and Oklahoma wheats were milled under the supervision 

 of an experienced miller, and the tlour was suhjeeted to the inspection 

 of the chief flour inspector of one of the largt^ milling companies of 

 Minneapolis. 



The milling was carried on in the usutU way." The screened wheat 

 was tirst passed through corrugated rollers to split the wheat kernel 

 and flatten the germ. As in ordinary milling it was necessary, in 

 grinding the samples, to dampen the wheat so as to prevent the bran 

 from breaking up into tine pieces and contaminating the straight-grade 

 flour. After passing through the second break, small amounts of 

 break flour'' and granular middlings were separated by means of a tine 

 screen and bolting cloths. The stock was removed from the second 

 break and the tailings passed on to the third break, which resulted in 

 the liberation and reduction of additional quantities of flour and mid- 

 dlings, and then on to the fourth break. With each reduction the 

 rollers were set a little closer. The granular middlings and stock were 

 passed through the smooth rollers three times and tinally all brought 

 together. All of the straight-grade flour was passed through a No. l-t 

 bolting cloth (illustrated in Plate II) and thoroughly mixed, the bran, 

 shorts, germ, and other ottals being removed at the difterent boltings 

 from the several breaks. 



This process of milling is known as the gradual reduction process. 

 Break flours are flrst produced and then the granular middlinigs are 

 liberated from the tailings and bran and reduced. The second break 

 flour is obtained largely from the interior or more floury portions of the 

 wheat kernel and is more starchy in character than later break flours. 

 The third break flour contains a higher percentage of gluten and other 

 proteids than the second break flour. The middlings from the second 

 break are more nitrogenous in character than those from the later 

 breaks. During the process of milling the break flours become more 

 nitrogenous, while the middlings })ecome more starchy in character. 

 The difierent break flours and middlings, with the exception of a small 

 amount which is separated as second clear or low-grade flour, are 

 finally united, thoroughly mixed and bolted, forming straight-grade 

 flour. 



In the milling of these wheats about 70 per cent of the entire wheat 

 was obtained as straight-grade flour. In the large mills, where the 



«For a somewhat more detailed account of the milling process, see Minnesota 

 Station Bui. 85, pp. 189, 190. 



6 In each reduction or "break" the "break flour" is the portion passinof through 

 the screen and bolting cloths. The "granular middlings" pass through the screen 

 but not the final bolting cloth, and are afterwards reduced to flour. The portion not 

 passing through the screen is known as the "tailings," and passes on to the next 

 "break." 



