15 



monly followed in connection with dietary studic« made in the house- 

 hold. It the percentage of protein, fat, and carbohydrates in every 

 article that was weij^hed had been known, the determining of the 

 amounts of nutrients in the food consumed would have been only a 

 matter of calculation. Such, in fact, was the case for any foods that 

 were eaten without cooking, as, for instance, some of the fruits. The 

 average composition, in the uncooked state, of most food materials in 

 common use in this country is quite well known from the results of a 

 large number of chemical analyses. But it will be observed that the 

 data of amounts served, obtained as explained above, are nearly all 

 for cooked foods, and very little is definitely known regarding the 

 composition of cooked foods. Even if a large number of analyses of 

 cooked foods were available they would not Ijc of much advantage, 

 because the method of preparation of any cooked dish varies in indi- 

 vidual cases in regard to the amounts of the several food ingredients 

 used, the amount of water added, the length of time of cooking, etc., 

 all of which factors influence directly the percentage composition of 

 the cooked article. 



The best method of determining the composition of the foods used 

 would, of course, be to analyze a sample of each, but the labor and 

 expense involved would be great and no laboratory facilities for per- 

 formino- such work were at hand. This method, therefore, was not 

 attempted. Another method for ascertaining the percentage composi- 

 tion of cooked foods, which has been used in a considerable number of 

 studies made elsewhere'* and w^hich has given results that are believed to 

 be reasonably accurate, consists in obtaining for any given cooked food 

 the weight and composition of each raw ingredient used in preparing 

 it and the total weight of the cooked article, from which data the per- 

 centage composition of the cooked food ma}' be calculated. This 

 method was adopted in the studies here reported and may be here 

 briefly described. 



Cooked foods may ])e grouped, for convenience, into three classes. 

 The first group will include such materials as meats, which in general 

 lose in weight during cooking, largely through loss of water or water 

 and fat. The second class will include such dishes as boiled oatmeal, 

 rice, hominy, etc., in which the only change in proximate composition 

 is that due to the addition of water in cooking, so that although there 

 is no loss of nutrients, the total amount in a given weight of the cooked 

 food is much less than in the same weight of the raw material. The 

 third class includes prepared dishes made up of a considerable number 

 of raw ingredients. Thus beef stew may contain beef, potatoes, onions, 

 carrots, parsnips, etc.; and puddings maybe made of flour, drippings, 

 butter or lard, sugar, eggs, and other ingredients. During baking, 



«New York State Com. Lunacy Rpt. 11 (1898-99), 12 (1899-1900), 13 (1900-1901). 



