EFFECT OF HEAT ON STARCH 



:eed 180 F., because if it does the protein in the soup coagu- 

 lates and rises to the surface as disagreeable and indigestible 

 scum. Soup is improved if it is cooked until the connective 

 tissue partly dissolves, because then the gelatin gets into the 

 soup and thickens and enriches it. After the soup is finished 

 the meat is tasteless; but although it is tasteless, it contains 

 considerable nourishment and should be strained off and used 

 for hash. When finely chopped and flavored with onion, 

 carrot, red peppers, tomato, and other vege- 

 tables or condiments it makes an appetizing 

 and nourishing dish. 



The double boiler. Slow cooking with 

 moderate heat is the best way to cook most 

 meat and milk, and hence it is desirable to have 

 simple devices by which the proper tempera- 

 ture can be secured. The double boiler is the 

 solution of the problem (Fig. 40). The vessel 

 containing the soup or boiling meat or the milk 

 is placed in a large vessel containing water. 

 The water in the outer vessel gives heat to the 

 inner vessel, which never gets as hot as the boiling point 

 of water. This removes all danger of overheating the food. 

 The double boiler is invaluable in a household, not only for 

 cooking of meats and heating of milk, but also for making of 

 cocoa and for the slow, thorough cooking of many foods. 



Effect of heat on starch. Most plant foods are eaten for 

 the sake of the starch which they contain. But the starch is 

 in the form of small grains with a hard outer shell which diges- 

 tive juices cannot penetrate; moreover, the hard starch grains 

 are massed together in cells whose walls are of cellulose, or 

 woody matter. Cooking in hot water softens the woody cell 

 walls and the starch shells, and causes the starch to absorb 

 moisture, to swell, and to burst open their shells. Uncooked 



FIG. 40. Double 

 boiler. 



