8 The Conipositioti and Food Value of Bread. 



forty foreign wheats 8 per cent. The gluten determined in 

 the manner desci'ibed by Jago only represents about two-thirds 

 of the total protein. The average content of protein in home- 

 grown wheat may therefore be taken as 10| per cent., as com- 

 pared with 12 per cent, in foreign wheats. These figures are 

 in accord with my own experience, and are further supported 

 by the well known fact that m.any foreign wheats are harder, 

 or, as the baker would say, stronger than average home-grown 

 wheats. It may be accepted, therefore, that if the same milling 

 process be employed in both cases, bread made from foreign 

 flour may be expected to contain appreciably more protein than 

 that macle from the home-grown article, but the difference is 

 in practice not likely to be very great. 



Before discussing the effect of different systems of milling 

 on the composition of bread it will be necessary to explain 

 briefly the roller milling process, and to define several terms 

 which it is evident from perusal of current periodicals are 

 commonly used with considerable misapprehension. The first 

 process which wheat undergoes in a modern roller mill is 

 cleaning, a process at which no one will cavil, especially in the 

 case of foreign wheats. The next step is known as conditioning, 

 the essence of which is so to adjust the moisture content of the 

 grain that the kernel is rendered soft enough to crumble well 

 between the rollers, whilst the skin of the grain is toughened 

 in order that it may undergo the least possible amount of 

 tearing, and thus remain in such a state that it may be readily 

 and completely removed from the flour. These are only 

 preliminaries to the milling proper which begins when the 

 wheat is passed between pairs of fluted rollers. The rollers 

 revolve rapidly in the same direction, but at different speeds, 

 and are set at such a distance apart that the grains are nipped 

 as they pass through, and at the same time torn a little because 

 the rollers do not travel at the same speed. The process 

 described above is known technically as a break, and wheat 

 commonly undergoes four such breaks in its journey through 

 the mill. The result of each of these is to produce a small 

 quantity of very flnely divided flour, known as break flour, 

 which is at once separated and, without further grinding, is 

 added to the rest of the flour at a later stage. At the same 

 time the rtbt of the wheat is crushed into a mixture of particles 

 of various sizes which are known technically as semolina. 

 The semolinas from the various breaks are passed through 

 several i)airs of smooth rollers in order to undergo the process 

 of reduction. Each reduction pulverises the semolinas more 

 finely and rubs the flour proper from the skin or bran. After 

 each reduction the mixed flour and bran passes through what 

 are known as purifiers, in which the finely divided particles of 



