- 6n - 



and proteolytic enzymes, the retarding action being very great in the 

 presence of quite minute amounts of nitrites. 



" Seeing that nitrous acid and its salts produce no known che- 

 mical action on starch, their inhibiting action on its digestion by 

 amylolytic enzymes can only at present be explained by their action 

 on the enzyme. 



" But in the case of protein there are two possibilities, action 

 on the enzyme and action on the substrate (protein). " 



From further studies of this question the author concludes that 

 " the presence of nitrous acid (even in the comparatively innocuous 

 form of a salt) hinders enzyme action. 



" Previous treatment with nitrous acid alters a protein in such 

 a way as to render it less readily susceptible to the solvent action 

 of digestive juices. " 



Similar results to those with starch were obtained in salivary 

 digestion of samples of bleached flour. 



In studies with separated gluten the comparative indigestibility 

 of that from bleached specimens of flour was marked. The de- 

 crease in digestibility was not proportional to the amount of nitrite- 

 reacting material present in the flour. " From this one would judge 

 that the main deleterious action is exerted by the nitrous fumes 

 while in contact with the flour, and the diminution of digestibility 

 does not depend on the more or less accidental quantity left behind. . . 



" The results obtained by those who have had the opportunity of 

 examining the breads show that the lessening of digestibility of the 

 bread is less marked than it is in the flour. This appears to be 

 partly due to the reduction of the amount of nitrite-reacting ma- 

 terial which occurs during baking, and in reference to the protein 

 (gluten) one can only suggest that the process of baking increases 

 the difficulty of digestion of that substance even in unbleached spe- 

 cimens, so that any difference in digestibility between a loaf made 

 from it and one made from bleached flour would not be so noti- 

 ceable. It can hardly be doubted that this, which after all is the 

 most important question from the standpoint of the consumer, has 

 had considerable influence with judges in deciding as they have 

 that the objection to artificial bleaching is more or less theoretical. 

 But knowing as we do the possible practical dangers which might 

 ensue were millers allowed a free hand in the use of the very strong 

 reagent they employ, it is necessary that a strict watch should be 

 exercised to keep its use within the limits of safety. " 



