15 



As pointed out in a former n^port" the ash content varies so regu- 

 larly in diflerent grades of milling products that it is possible to 

 determine the grade of flour by determining the amount of ash which 

 it contains. In these samples the ash content of the flour sample 

 agrees closely with that known to l)e pivsent in .standard grades of 

 straight-grade, entire-wheat, and Graham flour. 



COMPOSITION OF SAMPLES OF FOOD MATERIALS. 



The table below gives the data regarding the composition of the 

 foods consumed in the digestion experiments. The values given in 

 each case are the result of actual analysis, except that the percentage 

 of fat in the dr}^ matter of the flour is used as a basis in the calculations 

 for the fat content of bread. The results thus obtained are known to 

 be more accurate than those secured from the anal3'sis of the bread, 

 because during the process of bread making the fat of the flour is in 

 part rendered insoluble.'^ 



A sample of 100 grams from each loaf of bread used was dried and 

 a composite sample for anah'sis was then taken proportional to the 

 weight of the loaves and the quantit}^ consumed. This has been found 

 to be the most satisfactory method of sampling and preparing bread 

 for anah'sis. A composite sample of milk was made for each of the 

 digestion trials by reserving 25 cubic centimeters of the mixed milk 

 taken at each meal, 100 milligrams of potassium bichromate being used 

 as a preservative. 



Table 2.- 



-Conipositifm of bread and milk used in digestion txperimeiit>< uith Oregon and 

 OJdahoma irheat breads. 



aV. S. Dept. Agr.. Office of Experiment Stations Bui. 101, p. 9. 



bV. S. Dept. Agr., Ofiice of E.xperiment Stations Bui. 67, p. 45. 



c For explanation of the use of the factor 6.25 for calculation of protein in bread see p. 18, 



d Fat content of drv matter of flour. 



eHigh a.sh due to abnormal amount of preservative used iu composite sample. 



