BLEACHED FLOUR 



FRANK L. HALEY 

 (Hygientc Laboratory, University of Michigan) 



Bleached flour is a subject which has engaged the attention of 

 scientists and miliers for the past ten or more years, especially in 

 great wheat producing countries Hke our own. Whether or not the 

 use of bleached flour is injurious has been argued pro and con, but 

 the Solution of the problem is still in doubt. 



Naturally the question arises, "Why is flour bleached?" The 

 reason is purely a commercial one. For instance, a milier sends 

 out in the fall or spring a salesman with a number of samples of 

 flour which have not been bleached. Orders are taken for the 

 flour and four or five months later, when the delivery is made, the 

 flour has whitened or bleached to an appreciable extent, due to 

 atmospheric conditions. Quite naturally the purchaser objects to 

 accepting the consignment. For this reason the miliers have 

 bleached their flour in order to have it always uniform in color. 



Up to the last decade the method employed was to störe the 

 flour for a period of several months whereby the more or less marked 

 color was removed. 



A number of years ago Frichot^ observed that the gas produced 

 by discharges of electricity through air were capable of whitening 

 the flour. This he attributed to the production of ozone. Some 

 time later the Messrs. Andrews^ discovered that the bleaching was 

 brought about by the action of certain oxides of nitrogen, which are 

 produced when nitric acid is brought in contact with a reducing 

 agent such as ferrous sulfate. 



Numerous processes have been devised for the application of 

 this principle to the practical bleaching of flour. The process which, 

 up to the present time, has proved most serviceable is known as the 

 Alsop process. By this method air is pumped through a Chamber 



iFrichot: French patent, 277751 (1898). 

 2 Andrews (J and S) : English patent, 1661 (1901). 



440 



