CHAPTER VI 

 COOKING AND ITS EFFECT ON FOOD 



The changes produced in food by heat. Some foods, like 

 nuts, fruit, and milk, are eaten without being cooked ; others, 

 like meats, fish, and many vegetables, are eaten only after 

 careful cooking. Cooking changes the nature of foods and 

 usually makes them more easily digested or more completely 

 digestible and more appetizing. We digest a cooked potato 

 more easily than a raw potato; we digest a larger proportion 

 of cooked meat than of uncooked meat; we eat bread with 

 more relish than we would eat an uncooked flour and water 

 mixture; we enjoy a slice of savory, juicy roast more than a 

 slice of raw meat. The changes brought about in foods by 

 cooking are due to heat. All foods can be grouped into two 

 great classes, animal foods and vegetable foods ; but animal 

 and vegetable foods differ greatly in composition and in struc- 

 ture, and hence are differently affected by heat. In order 

 to cook the various foodstuffs to advantage we need to know 

 the effect of heat on the different classes of foods. 



The effect of heat on protein. The white of egg is albumen, 

 a form of protein matter. When the colorless, slimy white of 

 egg is heated to 134 F., it changes to a semitransparent, jelly- 

 like mass; when it is heated to 160 F., it coagulates or 

 becomes opaque and more or less solid. Experiments have 

 shown that albumen cooked at 160 F. is more easily 

 digested than albumen cooked at higher temperatures. The 

 effect of different temperatures on albumen can be seen by a 

 simple experiment done at home. Drop an egg into boiling 



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