FOODS AND CONDIMENTS 177 



The apparatus for this determination, especially that of LEO 

 LIEBERMANN, measures the expansion of the "doughed up" flour 

 under the influence of heat. 



I must not omit to state here, that flour whose baking capacity 

 has suffered (for instance by over-heating the gluten in grinding) 

 may be restored by the addition of common salt, plaster of paris, 

 water and alum. 



What has been said of flour applies also to prepared flours and in- 

 fant foods. In the latter, in addition to the proper composition, ease 

 of digestion and the property of preventing curdy coagulation of 

 milk in the stomach must be considered. It should be determined 

 whether a part of the difficult and complicated metabolism ex- 

 periments could not be substituted by simple testing according to 

 suitable colloid-chemical methods (swelling, etc.). 



In the investigation of dough, egg-dough and prepared products 

 (bread, noodles and macaroni), there occurs a phenomenon which is 

 very suggestive of a similar occurrence in the case of milk (see p. 

 345), namely, that one cannot recover the quantity of fat present in 

 the original flour by means of ether extraction, and indeed, it would 

 be interesting to determine how the adsorption of the fat occurs if 

 there is any adsorption. In this connection we may consider that in 

 the case of products made of egg-dough, we distinguish between free 

 lecithin (extractible with ether) and bound lecithin (extractible with 

 alcohol). Perhaps here, too, it is a question of adsorption. 



Next to milk, bread is our most important foodstuff. Bread making 

 may be briefly mentioned here. Bread is prepared from flour, which, 

 if it were consumed directly or made into a paste, would be badly 

 digested because the flour grains possess only a small swelling capacity 

 and the surface development of the entire mass is very small. The 

 making of bread renders the individual parts easily accessible to the 

 digestive juices. For this purpose, the dough (flour mixed with water) 

 is caused to ferment by the addition of yeast or sour dough. As a 

 result, the starch grains swell, burst and take up water, a portion is 

 converted into dextrin, part of which is still further broken down 

 into sugar, alcohol and carbonic acid gas. By foam formation, 

 the carbonic acid gas causes an enormous increase in the surface of 

 the mass. Incidental fermentative processes give the gluten, the 

 plant albumin, the power to swell up. This condition is completed 

 and to a certain extent fixed by baking. The dextrinization of the 

 starch is thus completed, the development of surface is increased by 

 the conversion of the water into steam and the expansion of the 

 carbonic acid gas, the gluten is coagulated and further changes are 

 stopped by the killing of the fermenting agents. 



