DIGESTIBILITY OF SOY-BEAN AND PEANUT FLOUES. 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 

 dupUcate 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 Hve steani 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 digestibihty 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-hke 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. 



