O'BHEA — ASPECTS OP MENTAL ECONOMY. 



131 



"The third stage is that of (c) achroo-dextrine, that in which the 

 starch is found in such perfectly cooked cereal foods as zwieback, 

 granose, and granola, and in the outer browned portion of the crust of 



bread. 



"In the second stage (b) the starch is further transformed into 

 erythro-dextrine, the form in which it is found in what might be 

 termed the half-cooked condition of well-baked ordinary baker's bread, 

 in crackers, rolls, gems, and similar foods. 



"The fourth stage is maltose or sugar, the final results of starch 

 digestion. The digestion of starch is accomplished in nature by the 

 action of so-called ferments or diastases. These are found abundantly 

 in both the animal and vegetable kingdoms, — in animals in the saliva 

 and other digestive fluids. In grains, the starch digesting ferment 

 or diastasis is found just beneath the bran, ready to form sugar for 

 the nourishment of the young plant. The starch found in green ap- 

 ples and other fruits is, by the process of ripening, converted first 

 into the various ferments or dextrines exclusively, and finally into 

 sugar. 



"The formation of the last form of dextrine is indicated by the ap- 

 pearance of a slight brownish color in the digesting mass. One 

 additional step only is necessary to convert the starch into sugar. 

 Heat is not capable of producing this step in the process, but when 

 achroo-dextrine, the last stage of heat digestion, the perfectly cooked 

 starch is brought into contact with the saliva of any other starch- 

 digesting ferment, the formation of sugar takes place instantaneously. 

 In other words, by the application of heat of sufficient degree for a 

 sufficient length of time starch may be converted first into amylo- 

 dextrine is produced by a temperature sufficient to cause the hydra- 

 tion or gelatination of starch in the formation of paste by cooking of 

 starch or flour. Longer cooking, or cooking for a short time at a 

 temperature above the boiling point of water, advances starch one 

 step along in the process of digestoin to the stage of erythro-dextrine. 

 Exposed to still higher temperature for a proper length of time pro- 

 duces achroo-dextrine. 



"Raw starch, on the other hand, when exposed to the action of the 

 saliva is not changed at all. Slightly cooked starch, that is, amylo- 

 dextrine or fluid starch, is converted into sugar only by the prolonged 

 action of the saliva. Erythro-dextrine, or imperfectly cooked starch, 

 is converted into sugar somewhat more quickly by the action of the 

 saliva, but in achroo-dextrine, or perfectly cooked starch, the trans- 

 formation takes place as soon as it is brought into contact with the 

 saliva. It is for this reason that a brown crust of bread, zwieback, 

 and well-toasted granose develop a distinctly sweetish taste when 

 chewed. 



