14 BULLETIN 717, U. S. DEPARTMENT OF AGRICULTURE. 



THE SUBJECTS OF THE DIGESTION EXPERIMENTS. 



Seven subjects with previous experience in experiments which 

 were made to determine the digestibiUty of some edible fats assisted 

 in this investigation. In general they were students of dental or 

 medical schools and were of normal health and appetite. Their 

 ages ranged from 20 to 40 years and their activities were such that 

 they would be classified as moderately-active persons. As is always 

 the case, they were instructed to exercise care in saving all uneaten 

 portions of the food, in separating and collecting the feces, and in 

 submitting reports concerning their physical condition before, after, 

 and during the experimental period. Inasmuch as all seemed in 

 their usual good physical condition throughout the entire time of 

 the experiments, no detailed discussion of these reports is given. 



PREPARATION OF EXPERIMENTAL DIETS. 



As in all studies of this character, it was desired that the nutrient 

 under consideration, in this case the proteins suppUed by soy-bean 

 and peanut flours, should comprise as large a portion as possible of 

 the total protein of the diet. It is essential that the foods studied 

 be ;prepared in an acceptable form and accordingly prehminary tests 

 were made of a number of methods of preparing these flours for 

 eating. As a result of these tests it appeared that ''tea biscuits" 

 similar to those so commonly made with wheat flour were well adapted 

 to this purpose. The recipe used follows: 



Recipe for Biscuits. 



16 cups flour mixture. 12 teaspoons salt. 



16 tablespoons lard, 10 tablespoons baking powder. 



6 cups water. 



In the soy-bean experiments the flour mixture was prepared by 

 mixing equal portions of wheat flour and soy-bean flour. In the 

 experiments with the peanut flour made from roasted kernels, the 

 proportion was two-thirds wheat flour and one-third peanut flour, 

 and in the experiments with peanut flour made from the raw kernels 

 from which the red skin was not removed, the proportion was one to 

 one. The wheat flour used in all cases was a commercial brand of 

 patent flour. 



Biscuits made with flour and soy-bean flour or peanut flour one to 

 one were satisfactory when only one-half or three-fourths inch in 

 thickness; thicker biscuits being very often rather "heavy," no doubt 

 because the amount of gluten in the flour mixture was rather small. 

 It was found that if the biscuits were very thoroughly baked (though 

 not scorched) they possessed a much better flavor than those not so 

 well done. 



