FREE INSTITUTE OF SCIENCE 



THE CHEMISTRY OF BREAD-MAKING 



laws of most countries and is rarely met as an adulterant of bread. It had the 

 effect, when added in the proportion of one-half lb. to 380 lbs. of flour, of making 

 the bread white, and also preventing the loaves, which come in contact with 

 each other in the oven, from sticking together and pieces being pulled out when 

 the loaves are separated. The reason for these effects has never been ascer- 

 tained. The use of alum was so prevalent at one time that it was popularly 

 known in bakeshops by such names as "stuff" and "rocky," for the purpose of 

 concealing its identity. As, in order to be of any value, it was needed in the 

 proportion of from three to five grains to each loaf of bread, and as the tests 

 for detecting it are comparatively simple and the penalties for its use very 

 severe, it is rarely found now. 



Copper sulfate (blue vitriol) is another substance that has been clan- 

 destinely used as a bread improver. In proportion of one grain to the loaf of 

 bread, it whitens and improves the appearance of bread, even when baked from 

 inferior and dark flour. It, too, is readily detected, and with the severe legis- 

 lation against its use, it has disappeared. 



In the case of both alum and copper sulfate the effect is probably due 

 to the retarding influence they have upon the enzyms of flour, as it is well 

 known that in damaged and inferior flours the enzyms are present in abnormal 

 amounts. 



Magnesium carbonate and calcium carbonate, chalk, have also been used 

 as flour improvers in the proportion of from twenty to forty grains of the sub- 

 stance to each pound of flour. Their effect is similar to that of lime-water, 

 sometimes mixed with the water used in making the dough. They are all 

 used in improving or restoring damaged flour, which they probably do by 

 neutralizing the acidity frequently present in such flour and also by retarding 

 the enzymic action just referred to under alum and copper sulfate, as in this 

 enzymic action the starch is hydrolyzed to sugar and the gluten decomposed 

 to a certain extent, and any retardation of this change, when abnormal, would 

 increase the water-holding power of the flour and improve the appearance and 

 texture of the loaf. 



Bleached flour also contributes its quota to the chemistry of the subject. 

 Flour is industrially bleached by exposing it to the action of chlorin, ozone, 

 nitrogen oxids or nitrosyl chlorid. The most marked changes occur in one of 

 the minor constituents of the flour, the fat, which forms combinations with 

 several of the bleaching agents, of greater or less permanence, which serve for 

 fixing the bleaching agent for identification later. 



