8 BULLETIN 1463, U. S. DEPARTMENT OF AGRICULTURE 
The titratable acidities of the patent and first and second clear 
flours made from the hard wheat paralleled their ash content. The 
coarsest portion showed the least acidity, with a gradual increase in 
acidity as the granulates became finer in size. No great difference 
was apparent in the titratable acidity of the various separates ob- 
tained by sieving the flour milled from the hard wheat coarse 
middlings stock sample No.12621, all of the flours passing through 
12, 16, 20, and 25xx sieves having practically the same degree of 
acidity. With the siftings from the soft red winter coarse mid- 
dlings stock sample No. 12550 there was a parallelism between the 
ash content, titratable acidity, and the fineness of division of the 
sample. The acidity of the different-sized flour particles obtained 
from samples Nos. 12551 and 12552 was irregular, and did not follow 
the size of the particle or the ash content. 
The hydrogen-ion content of the flour particles of different sizes 
was not appreciably different, as a difference of three-tenths in pH 
value would more than cover the change from one extreme in flour 
particle size to the other. 
The finest flour particles according to the gasoline color test were 
whitest in color. This fact seemed to be true with but one exception, 
namely, sample No. 12621. 
INFLUENCE OF EXCESSIVE GRINDING UPON THE QUANTITY AND 
QUALITY OF THE GLUTEN IN FLOUR 
Extensive tests were made of the influence of excessive grinding 
upon the quantity and quality of the gluten proteins of the flour. 
Information was sought concerning the effect of excessive grinding 
upon the quantity of crude protein, the percentage of wet and dry 
gluten, the imbibitional qualities of the gluten proteins, the percent- 
age of nitrogen soluble in cold water, and the influence upon the 
water imbibing constituent of the gluten protein, glutenin. 
The imbibiticnal qualities of the gluten proteins were studied by 
two methods. The percentage of wet and dry gluten in the samples 
washed with tap water were determined, and, from these data, the 
water absorbed or imbibed per gram of dry gluten was ascertained. 
Later the hydration capacity of the gluten protein was determined by 
noting for each of the treated flours the viscosity of flour and water. 
suspensions containing the equivalent of 2 grams of protein. The 
viscosity determinations were made on a MacMicheal viscosimeter. 
The test material was washed with 150 cubic centimeters of distilled 
water, and the readings made with a 2-centimeters bob, with the cup 
of the viscosimeter rotating at 76 revolutions per minute. 
Glutenin determinations were made according to the method of 
Blish.*?. Cold water soluble extract was determined by the methods 
of the Association of Official Agricultural Chemists.2 The data re- 
sulting from this phase of the investigation are shown in Tables 4 
and 5. The data in Table 4 relate to those samples of flour ground 
from 1 to 20 times, whereas the figures in Table 5 are from those 
flour samples ground to different degrees of fineness. 
7Blish, M. J., and Sandstedt, R. M. GLUTENIN—A SIMPLE METHOD FOR ITS PREPARATION 
AND DIRECT QUANTATIVE DETERMINATION. Cereal Chem. vol. 2, No. 2, p. 57. 
§ Official and Tentative Methods of Analysis of the Association of Official Agricultural 
Chemists. Revised to July 1, 1924, p. 227, par. 14 
