THE CHIEF FOODSTUFFS 355 



tho milling process, and white flour is obtained. Further, it is fre- 

 quently bleached with acids, and white calcium salts added to give 

 extra whiteness. There is economic loss in such bleaching processes, 

 which are, if anything, injurious to the consumer. When milled whole, 

 whole-meal is obtained; when only the bran is removed, " standard " 

 flour results. The chief protein, gluten, globulin-like in nature, 

 when mixed with water, becomes viscid, forming a dough. Gluten 

 consists of two portions gliadin, soluble in alcohol; and glutinin, 

 soluble in alkali. The viscidity is due to the gliadin. Grains poor 

 in gliadin e.g.. rice, oats do not form a dough when mixed with 

 water. 



Bread. The dough formed from flour is not a suitable food, 

 owing to its imperviousness to the digestive juices. When made 

 pervious by aeration, and baked, it becomes bread. 'This aeration is 

 performed by carbonic acid gas generated by the action of the yeast 

 which is mixed with the. dough, and of a diastase already present in 

 the flour. 



The Pulses. This group of dry foodstuffs contain in the dry state 

 a large amount of protein and carbohydrate, and, being cheap, are 

 valuable as articles of diet. They have the disadvantage, however, that 

 their physiological availability the amount absorbed during diges- 

 tion is considerably lower than with the animal foodstuffs. They 

 cannot be eaten dry, and when mixed with water and cooked they 

 become very bulky foods. The proteins of pulses and cereals do not 

 seem to be composed of such suitable "bricks" for building animal 

 tissues as are the proteins of animal foodstuffs. 



The Fruits are of value by reason of the anti-scorbutic principles, 

 the organic acids, salts and water they contain. Certain fruits also 

 contain appreciably large quantities of sugar. The banana, often 

 classed as a fruit, contains a relatively large amount of nutriment. 



Green Vegetables are of value as introducing a small percentage 

 of food, with salts, vitamines, and a certain amount of cellulose, 

 which stimulates the peristaltic action of the intestines. The salts 

 of the vegetable acids are converted into alkaline carbonates, and are 

 of importance in regulating the acidity of the blood. The green 

 foodstuffs, particularly spinach, also introduce iron into the body. 

 Chlorophyll is possibly a precursor of hemoglobin. 



Potatoes contain carbohydrate and a small amount of protein, but 

 this is in a most available form. They also contain vitamines, and 

 thus are of great importance to town populations. 





