780 DISCUSSION ON WHEAT: 
In the following a brief review is given of the factors with which 
strength has been associated in the past. The explanation of ‘strength’ 
from the chemical point of view must be treated as a separate problem. 
The preparation of sample loaves from a given flour still remains the 
most satisfactory test. It is essential that such loaves be prepared with 
scientific accuracy, under definitely standardised conditions, so that the 
only variable is the flour itself and possibly the amount of water used for 
doughing. Every mill desiring to produce uniform products is bound to 
have a laboratory for this purpose. 
Gluten. 
The oldest idea is that ‘strength’ is due to gluten; that in virtue of 
its elasticity this retains in the dough the gas produced during panary 
fermentation, and enables the dough to distend and keep up when baked. 
Flours containing most gluten should be the strongest. Experience has 
shown that a high gluten content is usually associated with strength, but 
in a great number of instances it has been found that of two flours, that 
with the higher gluten content behaves as the weaker when baked. Scientifi- 
cally, therefore, gluten content cannot be considered an absolute measure 
of strength, although obviously connected with it. 
Total Nitrogen. 
Some of the proteins of flour are soluble in water and therefore are 
removed during the process of washing out the gluten. The determination 
of total nitrogen in a flour is less liable to the errors affecting the empirical 
methods of estimating gluten, but the results of such determinations are 
roughly parallel to the gluten content and afford no absolute measure of 
strength. Equally unsatisfactory is the determination of nitrogen in the 
dry gluten. 
No doubt future work will involve the study of the forms in which 
nitrogen is present. 
All measurements hitherto made indicate that strength depends on the 
quality rather than on the quantity of the proteins in flour. However, the 
protein content, when judging normal flours, is undoubtedly the best single 
measure of strength. 
Quality of Gluten. 
No satisfactory chemical data by which this can be gauged have been 
obtained. Measurements have been made, for example, of the power of 
expansion when a definite weight of gluten is heated in metallic cylinders 
to a definite temperature. Of greater significance is the water-holding 
capacity or hydration ratio as measured by the ratio of the wet gluten 
immediately after extraction under carefully standardised conditions to 
its weight after drying. The ratio is on the average about 3: 1; that is, 
gluten carries about twice its weight of water. No generally accepted regu- 
larity has been demonstrated, but in gluten from strong flours the ratio 
is as low as 2.6, whilst in that from very weak flours the ratio is often 
above 3. As Mr. Hardy points out in the following paper, this ratio is; 
to be associated with the mineral content of the flour. 
Emphasis must be laid on the fact that the method of determining gluten 
by washing is purely empirical and requires careful standardisation before 
comparative results can be obtained. Measurements of gluten at the best 
are but a rough-and-ready guide to more exact determinations; they have 
the advantage that they can be made quickly without special apparatus. 
Gliadin Ratio. 
Crude gluten consists mainly of two proteins: gliadin, soluble in alcohol 
and glutenin, soluble in very dilute alkalis or acids. It has been suggested 
