INFLUENCE OF GRANULATION ON QUALITY OF FLOUR 7 
EFFECT OF EXCESSIVE GRINDING UPON THE CHEMICAL 
* COMPOSITION OF FLOUR 
Referring to Tables 1 and 2, it will be found from a quantitative 
standpoint that excessive grinding did not greatly affect the usual 
factors sought after in the chemical analysis of flour. 
As would be expected from excessive grinding,.there was a reduc- 
tion in the moisture content of the sample, the greatest change with 
but three exceptions being associated with the greatest amount of 
grinding. The percentage of ash and crude protein was not influ- 
enced. Color pigments extractable in gasoline were obtained in 
larger quantities on the average from those samples that were much 
overground. Although the change in the hydrogen-ion concentra- 
tion was not great, there was a fairly definite tendency for it to 
increase with the increasing fineness of division of the flour particle. 
No appreciable change in titratable acidity was noticeable. The 
method followed for making the hydrogen-ion determination was 
that described by Johnson ®* and Bailey. 
CHEMICAL COMPOSITION OF THE DIFFERENT-SIZED PARTICLES 
OF WHICH FLOUR IS NORMALLY COMPOSED 
The chemical composition of flour particles or granulates of vary- 
ing degrees of fineness sifted from middlings stocks ground to a 
normal degree of fineness and commercial flours is given in Table 3. 
It will be seen that the moisture content of these separates did not 
vary greatly. Neither was there any very noticeable tendency for 
this factor to increase or decrease as the fineness of particle increased. 
The ash content of the various flour separates from most of the 
materials was variable and was different in tendency of direction for 
each of the two classes of wheat studied. The ash content of the 
flour separates resulting from the ground soft red winter wheat 
middlings stocks was in most instances progressively lower as the 
flour particle decreased in size. The reverse of this was true for 
the different-sized particles sieved from the ground hard wheat mid- 
dlings stock and from the hard wheat patent, first, and second clear 
flours. In the case of these latter separates the material passing 
through the 20xx and 25xx silk cloths contained the largest quanti- 
ties of ash of any of the separates. The data in regard to the hard 
wheat materials seem to be in accord with the data submitted earlier 
by LeClerc and his coworkers from their studies with commercial 
hard wheat flours. Whether the difference in tendency shown be- 
tween the two classes of wheat in regard to ash content is due to 
differences in the nature of these wheats, or is the result of milling 
conditions, is not known and is a point under investigation. 
The protein content of the particles of flour that passed through 
the 25xx sieve was significantly less than the protein content of those 
flours which passed through the 8xx, 12xx, or 16xx sieves. On the 
other hand, with but two exceptions, there was not a great deal 
of difference in the protein content of the flour passing through the 
8xx, 12xx, and 16xx sieves. 
° JOHNSON, ARNOLD C., and Bainey, C. H. A PHYSIO-CHEMICAL STUDY OF CRACKER 
DOUGH FERMENTATION. Cereal Chem., vol. 1, No. 7, p. 329. 1924. 
