476 SCIENCE PROGRESS 



The Local Government Board has recently issued the third 

 of a series of Reports 1 relating to the bleaching of flour, in 

 which experiments are described that have been made in the 

 Laboratories of the Board. In this pamphlet certain results are 

 described, almost without comment, which are directly at variance 

 with the conclusions arrived at in former Reports on the same 

 subject, so that it seems desirable to criticise the pronouncements 

 in detail. 



In the former Reports (see Science Progress, April and 

 October 191 1) dogmatic statements were made as to the 

 injurious effects of bleaching flour — we are now favoured with 

 an account of experiments made to determine what bleaching 

 actually does to flour and the influence it has on the baking 

 qualities. 



The immediate effect of bleaching flour is to destroy the 

 colouring matter. It has been suggested by Wesener that 

 the pigment present is identical with Carrotene, a yellow un- 

 saturated hydrocarbon which recent researches, more particularly 

 those of Willstatter, have shown to be widely distributed in 

 plants. To confirm this suggestion, Dr. Monier-Williams has 

 compared the absorption spectrum of carrotene with that of a 

 flour extract and finds the two to be identical. It appears that 

 elaborate spectroscopic apparatus was obtained and much time 

 spent in research before this conclusion was reached — would it 

 not have been easier to have made use of the facilities offered 

 by one or other of the many University laboratories in which 

 such apparatus has long been installed ? Pure carrotene was 

 prepared from other sources and the effect produced on it by 

 nitrogen peroxide compared with that of oxygen. Nitrogen 

 peroxide bleaches carrotene, products containing nitrogen 

 being formed. When exposed to the atmosphere, carrotene 

 becomes lighter in colour and absorbs oxygen ; no nitrite could 

 be detected in a sample (o'2 gramme) after such exposure. 

 It is assumed that the action of the two gases gives rise to 

 different products and hence that their action on flour is also 

 entirely dissimilar. It is a far step to take from the first to 

 the second of these statements on such slender evidence. 



1 Report to the Local Government Board on the nature of the colouring matter 

 of flour and its relation to processes of natural and artificial bleaching. By 

 Dr. G. W. Monier-Williams. Food Reports, No. 19. (London : Wyman & Sons. 

 Price 3^.) 



