DIGESTIBILITY OF SOY-BEAN AND PEANUT FLOURS. 13 
on the 109-mesh sieve, and 12 per cent passed through the 109-mesh 
sieve. In view of the high protein content of the soy-bean press 
cake it seemed of interest to determine whether the distribution of 
nitrogen was uniform for the fractions remaining on the different- 
sized sieves. For this purpose a press cake which had been ground to 
duplicate the fineness of commercial soy-bean flour was chosen. That 
portion remaining on the 40-mesh sieve contained 5.95 per cent of 
nitrogen, that on the 70-mesh sieve 7.62 per cent, that on the 
90-mesh sieve 8.06 per cent, that on the 109-mesh sieve 8.21 per 
cent, and the portion that passed through the 109-mesh sieve con- 
tained 8.32 per cent of nitrogen. 
As often prepared in the commercial expression of peanut oil, 
the peanut press cake contains, in: addition to peanut kernels, the 
shells and the thin red skin which surrounds the kernel. Conse- 
quently such commercial press cake, though suited for use as stock 
feed or fertilizer, is not suitable for food purposes; especially is this 
true when moldy or unsound peanuts are included, when the shells 
are dirty, or when the oil is not expressed under sanitary conditions. 
In the commercial preparation of ‘‘salted peanuts” clean shelled 
peanuts of good quality are ‘‘blanched”’ by subjecting them to an 
atmosphere of live steam just long enough to loosen the skin sur- 
rounding the kernels but not long enough to allow the kernels to 
- absorb any appreciable amount of water vapor. A subsequent agi- 
tation of these kernels in a container provided with either a suction 
or a blower separates the skins from the kernels. The expression of 
oil by the cold process from such kernels produces a virgin oil and a 
high-grade press cake rich in protein. If shelled peanuts, from which 
the surrounding skin has not been removed, are pressed the resulting 
flour, though satisfactory for food purposes, is of a reddish tinge and 
has a somewhat different and less-pleasing flavor than that of the 
flour prepared from blanched kernels. 
In the study here reported of the digestibility of the proteins sup- 
plied by peanut flour a series of experiments was made with each of 
these types of flours. The peanut flour used in the first series of 
experiments was prepared by expressing the oil from blanched, 
roasted peanuts and grinding the resulting press cake. The flour 
used in the second series of experiments was prepared by the cold 
expression of shelled raw peanuts from which the red skin had not 
been removed. ‘The reddish flour obtained did not possess the rich 
nut-like odor of that obtained from roasted kernels. A sample of 
the flour from the unroasted peanuts was bolted and sieved to secure 
data regarding its fineness, and it was found that 54 per cent of the 
flour remained on the 40-mesh sieve, 23 per cent on the 70-mesh 
sieve, 13 per cent on the 90-mesh sieve, 5 per cent on the 109-mesh 
sieve, and 5 per cent passed through the latter sieve. 
