FOOD. 127 



In cooking meat by roasting or broiling, the external parts are 

 exposed to a rapid heat of 120 or 130 C. by which their albuminous 

 ingredients are coagulated, their coloring matter turned brown, and a 

 characteristic flavor developed. The interior, which does not rise above 

 65 C. remains red and juicy, its fluids being protected from evaporation 

 by the coagulation of the outer portions. In boiling, where the meat 

 is cooked by contact with the boiling water, none of it can rise higher 

 than 100 C., but this temperature may penetrate through the whole 

 of its substance, producing a uniform decolorization. Notwithstanding 

 the coagulation of the albuminous liquids, the fibrous connective tissues 

 are gelatinized, and the muscular flesh thus partially softened and dis- 

 integrated. On the whole, the effect of cooking upon meat is to increase 

 the consistency of its albuminous ingredients, its principal benefit being 

 the attractive flavor developed by heat, and an increased digestibility 

 from the same cause. By either method, meat loses in cooking from 

 25 to 30 per cent, of its weight, principally by the escape of water and 

 liquefied fat. 



Eggs. The eggs of various animals are employed for food, as those 

 of the common fowl, the duck, goose, turkey, sea-fowl, turtles, and many 

 fish. Those of the common fowl may be considered as representing the 

 general qualities of this kind of nutriment. They consist of the globu- 

 lar "yolk," surrounded by a layer of albumen or "white." The com- 

 position of these two portions is nearly the same, excepting that the 

 yolk contains a larger proportion of solids, and particularly of fatty 

 matter, which gives to it its yellow color and rich flavor. A compara- 

 tive analysis of the yolk and white is as follows : 



COMPOSITION OF THE FOWL'S EGG. 



Yolk. White. 



Albuminous matter .... 16.0 20.4 



Fat 30.7 



Mineral salts 1.3 1.6 



Water 52.0 78.0 



100.0 100.0 



The mineral matters consist mainly of sodium and potassium chlorides, 

 potassium sulphate, and lime and magnesium phosphates. Of the entire 

 contents of the egg, exclusive of shell, the yolk constitutes one-third 

 and the white two-thirds. Cooking produces but little effect upon eggs 

 except to coagulate their albuminous matters, developing only a slight 

 flavor under the influence of heat. 



Vegetables. Of the different vegetables used as food, some are 

 valuable for their starchy and albuminous ingredients, others mainly 

 for their saccharine and watery juices. The former are nutritious in 

 the ordinary sense of the word, though much less so than bread or 

 animal food ; the latter are useful for supplying certain materials con- 

 tained in fresh vegetable juices, which are essential to the maintenance 

 of health. The most important of the first group are represented by 



