104 



PHYSIOLOGY FOR DENTAL STl'DKNTS. 



Cost 



in cents 



per portion 



Bread 5 



Apple pie 5 



Boston pork 



and beans 15 



Ham sandwich ... 5 



Corn beef hash ... 15 



Beef stew 15 



Club sandwich ... 25 



Sliced pineapple .. 5 



Mayonaise 20 



Calories 

 in for 5 cents 



933 

 337 



276 



170 



170 



154 



82 



36 



13 



Cost 

 in cents 

 per 1000 

 calories 

 5 

 15 



18 

 30 

 30 

 32 

 61 

 138 

 35 



(Lusk) 



The above table is not by any means from a cheap restaurant. 

 By economy and judicious purchasing it is possible even in New 

 York to purchase 1,000 calories having the proper proportion of 

 calories for 8 cents, so that a working man may easily cover his 

 dietetic requirements for 25 cents a day, exclusive of the cost -[' 

 cooking. All he spends above this is for personal taste and relish. 



Chemistry of the Commoner Foodstuffs. 



The accompanying diagram (Fig. 9) indicates the composition 

 of some of the commoner foods and is self-explanatory. There 

 are certain foodstuffs concerning which a little more detail may 

 however be advisable. 



Wheat Flour, besides a large amount of starch, contains two 

 proteins, glutein and gliadin. When the flour is mixed with 

 water and then kneaded, it forms dough, because the proteins 

 change into a sticky substance called gluten. As dough the flour 

 is not a suitable food, because the digestive juices cannot pene- 

 trate it. To render it digestible the dough must be made porons 

 and this is accomplished by causing bubbles of carbon dioxide 

 gas to develop in it, either by mixing it with baking powder 

 which is composed of a bicarbonate and an organic acid (tar- 

 taric) or by keeping it in a warm place with yeast, which fer- 

 ments the sugar that is present. The sugar is developed from 

 the starch by the action of the diastase (see p. 44) present in 

 the flour. 



