frying-, or iiny mode of cooking, thcro may be a slight loss of nutri- 

 ents through volatilization of fat, burning of sugar, etc., but such 

 losses are believed to be very small. Calculating the composition of 

 such foods on the basis of the amount and composition of the raw 

 ingredients used necessitates the assumption that there is no very 

 apprecia1)le loss of nutrients in cooking, an assumption which seems 

 justitied by the fact that in a considerable numl)er of comparisons it has 

 been observed that the percentages of nutrients in such made dishes, 

 as estimated by the method used in these studies, are extremely close 

 to the percentages found by actual analysis. 



In the case of those materials in which the total amount of nutri- 

 ents is the same in the cooked as in the uncooked food, the principle 

 of the calculation is simply one of proportion, and maybe stated thus: 



The weight of the cooked food is to the weight of the raw food as 

 the percentage composition of the raw food is to *■ (the percentage 

 composition of the cooked food); 



Or, to put it in another way: 



The total amount of nutrients being the same in the cooked food as 

 in the raw, the percentage composition of the cooked food is to be 

 ol)tained l)y di\iding the total amount of each nutrient by the total 

 weight of the cooked food (and multiplying by 100), since the propor- 

 tion of protein, fat, or carbohydrates varies directly with the change 

 of weight of the raw material in cooking. 



In calculating the composition of cooked meat from that of the 

 uncooked, allowance must of course be made for the fat cooked out 

 and for bones removed. The method of making the computations 

 will perhaps be made clearer by the following typical examples, one 

 for each of the three classes of cooked foods described above. 



The first illustration is that of meat from which fat was cooked out. 

 A lot of corned beef weighed 799 pounds ))efore cooking and 51.5., 5 

 pounds when cooked, 56 pounds of the loss in weight being due to fat 

 cooked out. Raw corned l)eef as purchased has been found by aver- 

 age of several analyses to contain 11.8 per cent protein and 18.1 per 

 cent fat; hence the amounts of protein and fat in the raw beef as pur- 

 chased would be 118 and 115 pounds, respectively. But since 56 

 pounds of fat cooked out, this must be deducted from the total amount 

 of fat, leaving 118 pounds protein and 89 pounds fat. The meat and 

 bones after cooking weighed 515.5 pounds, of which 114 pounds was 

 found to be bones, leaving 101.5 pounds of cooked edible meat con- 

 taining 118 pounds of protein, or 29.4 per cent, and 89 pounds of fat, 

 or 22.2 per cent. The table following summarizes the data. 



