54 HUMAN BIOLOGY 



pass out into the broth, making it rich and nutritious. When the 

 stew is allowed to simmer for several hours on the back of the stove, 

 the meat itself becomes tender and readily digestible. The addi- 

 tion of vegetables makes it a most nourishing and palatable dish. 



63. Boiling meats. — When the meat itself is to be eaten, and 

 the broth is not to be used, the whole piece should be plunged into 

 boiling water for a few moments. In this way the protein on the 

 surface is quickly coagulated, and the crust thus formed prevents 

 the loss of the meat juices. The temperature of the water should 

 then be reduced somewhat below the boiling point by pushing the 

 kettle toward the back of the stove, and the meat should then cook 

 slowly until it is done. A piece of meat, when cooked in this way, 

 is tender and juicy throughout. If, however, the water is kept at 

 the boiling point (212° F.), the meat may be easily torn apart, but 

 the fibers are foimd to be hard and stringy. 



64. Roasting and broiling. — The best method of cooking the 

 flesh of animals, if the broth is not desired, is by roasting or by broil- 

 ing, since smaller percentages of the nutrients are lost than is the 

 case in boiUng. The outer layer of protein must, however, be coagu- 

 lated at once, and for this purpose a very hot fire is needed. 



When the piece to be roasted is small, the high temperature 

 should be maintained until the meat is cooked. A large roast, 'on 

 the other hand, after the outer covering has been coagulated, requires 

 a slower fire and a longer time ; meat is not a good conductor of 

 heat, and a hot oven would scorch the outside before the central mass 

 could become thoroughly cooked. A better crust is formed on the 

 outer surface of the roast if the meat juices in the pan (mostly fat) 

 are frequently poured over the surface of the roast. This is called 

 "basting." 



65. Reasons for cooking vegetables. — The starches, which are 

 present in large quantity in foods of vegetable origin, are usually 

 inclosed in cells, the walls of which are formed of indigestible cellu- 

 lose. Hence, before starch can be digested, it must be freed from 

 this cellulose envelope. This is largely accomplished by cooking, 



