56 



have studied the composition of macaroni and similar goods, but tlie 

 amount of availal)le information on this su])ject is not large. 



In order to determine the nutritive value of macaroni made from 

 American wheat, two series of experiments were undertaken which 

 included the milling of the wheat, the preparation of the macaroni, 

 and the determinations of its nutritive value when eaten b}^ health}^ 

 young men who had a fair amount of nuiscular exercise. The wheat 

 used in the series of experiments made in 1904 was grown at the North 

 Dakota Experiment Station, and that used in the experiments made in 

 1905 was obtained at the North Dakota Substation, located at Edgeley. 

 In both series the wheat was milled in the new experimental roller 

 mill (PI. IV) at the Minnesota Experiment Station and the semolina 

 manufactured into macaroni by the Miimesota Macaroni Company, of 

 St. Paul. 



MILLING OF SAMPLES. 



In the milling system employed the cleaned wheat is passed along to 

 the tirst break, where it receives its tirst reduction. The ''chop" is 

 carried to the sifter by means of an elevator and separated into break 

 flour, middlings, coarse bran, and material for the second break, where 

 similar streams are obtained. The middlings are reduced between 

 smooth rollers, purified by the aspirator, bolted in the sifter, and the 

 reduced and purified product recovered as middlings flour or patent 

 flour. In the system of milling followed, two grades of middlings 

 flour, i. e., first and second, a break flour, and a low-grade flour, are 

 obtained. From 70 to 75 per cent of the wheat milled, depending 

 upon its quality, is recovered as flour with this experimental mill, and 

 from 35 to 30 per cent is returned as bran, shorts, and feed. 



The general plan of the milling system is shown in the figure here- 

 with (fig. 1). 



The milling plant used consists of two stands with corrugated and 

 smooth rollers. By passing the material over the rolls a second 

 time a four-break system of milling is secured. The milling of durum 

 wheat for the production of semolina requires a different graimla- 

 tion and bolting of the middlings from that used in the preparation 

 of flour from ordinary hard wheats for*bread-making purposes. The 

 aim is to secure medium coarse granular middlings, i. e., semolina, 

 rather than fine flour, and it follows that the proportion of wheat 

 obtained as middlings, which would ordinarily be reground, is greater 

 than in flour milling. Manufacturers state that for macaroni making 

 semolina is required which will not pass through a No. 10 bolting 

 cloth. In milling for bread-making purposes the flour must be fine 

 enough to pass through a No. 10 or 11, and in some cases a No. 12 or 

 14 bolting cloth. 



For the investigations reported herewith the Kubanka variety of 



