CERDAIv FOODS. 125 



of starch. Raw starch, while a valuable food for our farm 

 stock, is digested by man with extreme slowness. This seems to 

 be due in part to the very thin covering, apparently of cellulose, 

 with which each kernel of starch is invested. When subjected 

 to high temperature the starch grains swell and burst, very much 

 as a grain of corn "pops" under similar conditions. At the same 

 time a portion of the starch — the amount varying with the tem- 

 perature and the duration of the heating process — undergoes a 

 chemical change. Whereas raw starch is practically insoluble 

 in cold water, prolonged heat converts it into dextrin, a soluble 

 carbohydrate into which all starch must be changed before it is 

 transformed into a sugar, in which form only it can be absorbed. 



The conversion of starch into a soluble form may be accom- 

 plished by other means. During the germination of the cereal 

 grains the large amount of starch there stored up is converted 

 into maltose, a soluble sugar, through the action of a ferment 

 (diastase) which is there produced for this special purpose. The 

 amount of the ferment formed is much more than is required to 

 transform the starch of the barley itself. Adv^mtage is taken 

 of this fact in the use of malt, so extensively employed in brew- 

 eries. This malt is produced by causing barley to sprout, the 

 germinating process being checked when the amount of the fer- 

 ment is greatest. If a quantity of malt be mixed with a cereal 

 food under conditions favorable to the action of the ferment, a 

 "malted'' or predigested food results. 



It would appear from the advertising matter that many manu- 

 facturers attach great importance to the conversion of the cereal 

 starches into soluble forms. No attempt has been made in these 

 laboratories to determine how far the efforts to accomplish this 

 end have been successful. The matter has received attention 

 elsewhere,* however, and the results are of interest. The table 

 given below shows the amount of dextrin found by McGill in 

 eight different cereal products. 



Perfectly sound and untreated cereal grains contain practi- 

 cally no dextrin or maltose. Their presence in these foods is 

 due to the action of heat or malt upon the starch. McGill found 

 that the Ralston Breakfast Food (a rolled wheat) and rolled 

 oats contained but small amounts of dextrin ; while in Force and 

 Grape-Nuts from one-fifth to one-third of the total starch had 

 been dextrinized. 

 9 



