Mr Wood, A New Chemical Test for “ Strength ,” etc. 115 
A New Chemical Test for “ Strength ” in Wheat Flour. By 
T. B. Wood, M.A., Gonville and Cains College. 
[ Received 18 February, 1907.] 
Flour made from different varieties of wheat, or from wheat 
of the same variety grown in different districts, produces, when 
baked, bread of varying character. For instance, some flours 
absorb, when made into dough of suitable consistency for baking, 
nearly three-quarters of their own weight of water, whilst others 
can take up less than one-half. Again the loaf baked from the 
same weight of two different flours may vary more than thirty 
per cent, in volume, the shape may be entirely different, and on 
cutting the two loaves across they may be found to vary 
enormously in both colour and texture. 
The question of baking value or “strength” as it is commonly 
called, was recently fully discussed by Humphries and Biffen 1 , 
who adopt as their definition of the strength of a flour “its 
capacity for making a large, well-piled loaf,” a definition which 
excludes water-absorbing power, but which appears to include 
at any rate the three qualities of size, shape, and texture. 
The definitions of strength adopted by authorities on baking 
vary widely, and no one appears to use the word to denote a 
single quality. This probably explains the very divergent results 
obtained by numerous investigators, who appear to have tried 
to find a single chemical or physical explanation for the sum 
of several quite independent properties. 
The cause of strength has always been supposed to reside 
in the proteids of the flour. Various investigators have suggested 
from time to time that it was due (1) to the percentage of total 
proteid in the flour, (2) to the percentage of alcohol soluble 
proteid or gliadin in the gluten or total proteid, or in the flour. 
Undoubtedly, each of these factors is associated with strength 
in many cases, but there are so many exceptions that none of 
the suggestions can be said to solve the problem of the meaning 
of “strength.” 
When beginning to work at the subject, it seemed to me 
that it was useless to attempt to find a single explanation of so 
complex an idea. Probably each of the factors which make up 
“strength” is more or less independent of the others, and must 
therefore be attacked as a separate problem. Up to the present 
therefore I have directed my attention chiefly to investigating 
the conditions which influence the volume of the loaf produced 
by a given weight of flour. 
1 Journal of Agrie. Science , Vol. ii. No. 1 , p. 1 . 
VOL. XIV. FT. I. 
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