Nov., 1931] FOODS IN A COLLEGE COMMUNITY 5 



analysis a composite, aliquot sample of the food eaten bj' a group of in- 

 dividuals, it is equally as simple to prepare a composite, aliquot sample 

 of the total waste collected during any definite period of time, and the 

 oxy-calorimeter makes it possible to determine the actual caloric value 

 of such a mixed mass of waste readily and accurately. 



From our earlier study^ it was found that if the air-dry weight of a 

 mixture of foods were known, the multiplication of this air-diy weight in 

 grams by the round number 5 gives with astonishing accuracy the true 

 caloric value of the food. Indeed, this factor has been recommended for 

 the use of physicians and dietitians in hospitals as a rapid means of cal- 

 culating accurately the energy value not only of simple foods of well- 

 known composition in a mixed diet, but likewise of the most complicated 

 culinaiy mixtures. If some such factor could also be established for the 

 caloric value of the edible food waste per gram of air-diy weight, the 

 problem of correction for table waste in dietaiy studies of groups of in- 

 dividuals would be greatly simplified. Since waste as a whole should 

 normally represent only a relati^-ely small fraction of the total food 

 served, it is obvious that a fairly large en-or in the factor used for com- 

 puting the caloric value of waste per gram of air-diy weight could be 

 permitted without seriously affecting the calculation of the actual energy 

 intake. It was believed that combustions made with the oxy-calorimeter 

 of various samples of plate scrapings taken from the ordinarj' college 

 table might establish a caloric value of the air-dry matter of edible food 

 waste that would be applicable in dietary studies in practically all cases 

 where groups of individuals are eating under the same conditions. Ar- 

 rangements were therefore made with one fraternity house and two so- 

 rority houses at the Univei-sity of New Hampshire to collect the waste 

 of edible material, to prepare air-dr}- samples of the same, and determine 

 their heats of combustion with the oxy-calorimeter. By edible material 

 is meant food deprived of its ordinary refuse, such as fruit skins, fruit 

 stones, and meat bones. If visible amounts of fat were served and the 

 fat was not relished by the individual and left uneaten, this was consid- 

 ered as unused edible material. Edible waste that could be scraped off 

 the serving dishes and the cooking utensils was likewise included, but 

 not the inedible kitchen refuse. Consequently all our combustions of 

 waste dealt with the unused edible food, both that in the kitchen and 

 that in the dining room. 



In addition to the combustions of samples of food waste, the energy 

 values for a number of mixed meals and a number of so-called "extra 

 foods" were also obtained. To give some hint as to the amount of pro- 

 tein in these waste foods and mixed meals, the nitrogen content was de- 

 termined by the Kjeldahl process. No effort was made, however, to ap- 

 portion the calories from protein, fat, and carbohydrate. Comparisons 

 were made between the energ>' and the protein content of the food 

 served and of the edible waste, in order to calculate what percentage of 

 the energy and the protein in the total food served was discarded un- 



^Benedict and Farr, loc. cit. 



