DIGESTIBILITY OF SOY-BEAN AND PEANUT FLOUBRS. 25 
GENERAL CONCLUSIONS REGARDING THE VALUE OF SOY BEAN AND 
PEANUT FLOURS AS FOOD. 
Soy beans and peanuts are classed as a ‘‘sure crop,” and both 
yield valuable products (press cakes) whose chief use at present is 
said to be for stock feeding. The boll weevil has made the growing 
of cotton unprofitable in some sections of the South. As a result, 
during the last season or two, the culture of soy beans and peanuts 
has increased with unusual rapidity. This situation, coupled with 
the present great demand for oils, has caused many of the cotton- 
seed-oil millers to utilize their machinery for pressing soy beans and 
peanuts. The resulting soy-bean and peanut press cakes when 
ground yield a flour very rich in protein and, as compared with 
cereal flours and meals, fairly rich in fat. ; 
Chemical analyses reported by previous investigators of glycinin 
and arachin, soy-bean and peanut proteins, show that both, by hy- 
drolysis, yield lysine and tryptophane, two amino acids recognized 
as essential for growth and maintenance. 
Investigators studying the biologic value of these proteins by ex- 
periments with laboratory animals have shown that soy-bean and 
peanut proteins when employed as the sole source of protein in an 
otherwise adequate diet support in a satisfactory manner the normal 
body processes of growth, maintenance, and reproduction. 
In view of these facts it seemed highly desirable to study the diges- 
tibility of the proteins supplied by soy-bean and peanut flours pre- 
pared by grinding press cakes obtained by the expression of oil from 
clean sound soy beans and peanuts. 
The experiments here reported were made with normal young men 
students engaged in moderately active pursuits. The soy-bean and 
peanut flours were eaten in the form of a well-known type of ‘‘quick 
bread” or ‘‘biscuit’’ as a part of a simple mixed diet. None of the 
subjects reported any digestive or other physiological disturbances 
in connection with these diets, indicating that as regards the time 
and method of cooking, the soy-bean and peanut flours were satis- 
factory. 
The figures, 85 per cent for the digestibility of soy-bean protein 
contained in ground cake and 86 per cent for the digestibility of 
peanut proteim present in ground cake, indicate a very satisfactory 
utilization of these proteins by the human body. If allowance has 
been made for that portion of the fecal nitrogen which resulted from 
epithelial cells and bacteria instead of including it in the undigested 
residues of the soy beans and peanuts, the coefficients of digestibility 
of soy-bean and peanut proteins would have been somewhat higher. 
The figures obtained for the digestibility of the proteis supplied 
by soy-bean and peanut press-cake flours compare very favorably 
with those obtained for cereal proteins and are somewhat higher than 
