572 FOODS AND FOOD ADULTERANTS. 



As I have previously indicated, the matter of the physiological effect 

 of the residues left by baking powders is not properly a chemical prob- 

 lem. On account of the interest and importance attached to it, how- 

 ever, it would seem necessary to give here somewhat of a resume" of the 

 subject without attempting to arrive at a definite conclusion, or to set- 

 tle, arbitrarily, the question as to whether the sale of certain forms of 

 powders should be prohibited. 



For a proper understanding of the alum question it is necessary to 

 explain that the use of alum in bread-making is prohibited in countries 

 having food adulteration laws, such as England and France. This is 

 partly on account of its injurious effect upon the system, but principally 

 because of its peculiar action, not yet well understood, in improving 

 the color and appearance of the bread to which it has been added, so 

 that a flour of inferior grade, or even partially spoiled, may be used to 

 make bread which will look as well, to all appearances, as bread made 

 from much better grades. 



Blyth l speaks as follows of this use of alum in bread : 



Alum is added to bad or slightly damaged flour by both the miller and the baker. 

 Its action, according to Liebig, is to render insoluble gluten which has been made 

 soluble by acetic or 1 actic acids developed in damp flour, and it hence stops the undue 

 conversion of starch into dextrine .or sugar. The influence of alum on health, in. the 

 small quantities in which it is usually added to bread, is very problematical, and 

 rests upon theory more than observation. But notwithstanding the obscurity as to 

 its action on the economy there can be no difference of opinion that it is a serious 

 adulteration, and not to be permitted. 



Allen 2 says : 



Alum, or an equivalent preparation containing aluminium, is by far the most com- 

 mon mineral adulterant of bread, though its use has greatly decreased of late years* 

 Its action in increasing the whiteness and apparent quality of inferior floni is un- 

 questionable, though the cause of its influence has not been clearly ascertained. 

 Whether there be sufficient foundation for the statements made respecting the in- 

 jurious effects of alumed bread on the system is still an open question. 



The following is from Hassall: 3 



With reference to the use of alum, Dr. Dauglish has written : " Its effect on the sys- 

 tem is that of a topical astringent on the surface of the alimentary canal, producing 

 constipation and deranging the process of absorption. But its action in neutralizing 

 the efficacy of the digestive solvents is by far the most important and unquestionable. 

 The very purpose for which it is used by the baker is the prevention of those early 

 stages of solution which spoil the color and lightness of the bread whilst it is being 

 prepared, and which it does most effectually ; but it does more than needed, for, 

 whilst it prevents solution at a time that is not desirable, it also continues its effects 

 when taken into the stomach, and the consequence is that a large portion of the 

 gluten and other valuable constituents of the flour are never properly dissolved, but 

 pass through the alimentary canal without affording any nourishment whatever." 



The manufacturers of alum baking-powders, however, claim that the 

 hydrate of aluminium which is left in the residue is insoluble in the 



1 Foods, Composition and Analysi ', p. 168. 



8 Commercial Organic Analysis, 1, p. 371. 



Food, its Adulterations, and the Methods for their Detection, p. 344. 



