FOODS AND DIETARIES 341 



senting its fat value ; F and P represeni- 100 per cent fat and protcid 

 respectively. 



The threefold constitution of any particular food may be represented 

 graphically by the position of a point in this triangle. Thus the 

 point O representing milk is locateil at a height above CF 19 prr cent of 

 the total height of PC, which shows that 19 per cent of the food value 

 of milk is proteid ; and at a distance to the right of CP towards F, .j2 

 per cent of the distance, signifying that 52 per cent of the food value of 

 milk is fat. 



In the triangle at the right, the rectangle wxyz is known as the normal 

 rectangle, and shows where a well-balanced food or combination of foods 

 would be appro.ximatel.v located. 



Two or more foods may be plotted as follows : The combination of 

 portions equal in calorie value is represented by a point midway between 

 them. If the portions are unequal, the point will, of course, be pro- 

 portionally nearer the point locating the larger portion. Likew ise, when 

 three foods are combined, the point is first located for two, then this with 

 the third, the resulting combination with the fourth, etc. 



Thus we can demonstrate to the eye the value of various foods or 

 combinations of food in a dietary. (For laboratory directions, see Labora- 

 tory Manual, Prob. XLII.) 



Food Waste in the Kitchen. — Much loss occurs in the improper 

 cooking of foods. Meats especially, when overdone, lose much of 

 their flavor and are far less easily digested than when they are 

 cooked rare. The chief reasons for cooking meats are that the 

 muscle fibers may be loosened and softened, and that the bacteria 

 or other parasites in the meat may be killed by the heat. The 

 common method of frying makes foods less digestible. Stewing 

 is an economical as well as healthful method. A good way to pre- 

 pare meat, either for stew or soup, is to place the meat, cut in small 

 pieces, in cold water, and allow it to simmer for several hotirs. 

 Rapid boiling toughens the muscle fibers by the too rapid coagula- 

 tion of the albuminous matter in them, just as the white of egg 

 becomes soUd when heated. Boiling and roasting are excellent 

 methods of cooking meat. In order to prevent the loss of the nutri- 

 ents in roasting, it is well to baste the meat frequently ; thus a 

 crust is formed on the outer surface of the meat, which prevents the 

 escape of the juices from the inside. 



Vegetables are cooked in order that the cells containing starch 

 grains may be burst open, thus allowing the starch to be more easily 

 attacked by the digestive fluids. Inasmuch as water may dissolve 



