Xov., 1931] FOODS IN A COLLEGE COMMUNITY 33 



values of the mixed meals studied in our earlier research.* The average 

 energy content in these instances varies according to the meal of the 

 day, the breakfasts having the lowest value. Since the breakfasts were 

 in large part of a purely carbohydrate nature with a minimum content 

 of fat, this is to be expected. The total daily meals, when analyzed to- 

 gether, had an average caloric value of 5.0 calories, but the meals ana- 

 Ij'zed separately contained more nearly 4.7 or 4.8 calories per gram of 

 air-dry matter. This is in full conformity with the results shown in the 

 upper portion of Table 10 for the combined lunch and dinner samples. 

 In our earlier report a round figure of 5 was suggested as being of prac- 

 tical use in calculating the energy content of mixed meals from the 

 known, air-dry weight in grams. From the results of this present study 

 and a closer inspection of the earlier observations it would appear that 

 in all probability a slightly higher degree of accuracy could be obtained 

 in estimating the energy intake in mixed foods by using the factor 4.7. 



In the lower part of Table 10 are given the average values for edi- 

 ible waste derived from the detailed data in Tables 1, 2, and 7. Twenty- 

 three samples of edible waste containing no visible fat had an average 

 value of 5.0 calories per gram of air-dry matter. These samples were 

 collected at the fraternity house. If, with the results for these samples, 

 the data for the two samples (743 and 751B) containing fat are included, 

 the average becomes 5.3 calories. Twelve edible waste samples contain- 

 ing no visible fat, collected at House S-1, had an average energy value 

 of 4.9 calories. The food wasted by Students 1 to 4 at House S-2 varied 

 in energy content from 4.3 to 5.8 calories, but on the average contained 

 4.9 calories per gram. Since it is to be expected that plate scrapings 

 would consist in large part of residues of mixed meals, with a possible 

 preponderance of fat, it is not surprising that the caloric value of edible 

 waste per gram of air-dry material is on the average so close to the 

 round value suggested in our earlier report for mixed meals, namely, 5 

 calories. It is clear, however, that the presence of a large amount of 

 fat will alter materially the caloric value of edible waste. When large 

 amounts of edible fat are served, are not relished by the person eating 

 the meal, and are left on the plate, obviously the percentage of fat in 

 the plate scrapings will be larger than the percentage of fat in the food 

 served. The chief problem, therefore, in the handling of waste food is 

 the fat. 



Our study leads to the conviction that in all future dietetic studies 

 edible waste as such, distinguished from kitchen refuse, should first be 

 air-dried. The air-diy weight in grams should then be multiplied by 

 the factor 5, if the waste sample contains no visible fat. If there is 

 visible fat in the sample and it can be easily skimmed off, it should be 

 removed, its weight determined separately, and the caloric value of this 

 waste fat computed on the basis that each gram is equivalent to 9 cal- 

 ories. This factor of 9 allows for a certain amount of moisture and 

 probably non-fatty material unavoidably included in the removal of the 



^Benedict and Farr, loc. cit. 



