WINNIPEG, 1909. 785 
This being the case it is obvious that any attempt to correlate strength 
with the physical properties of gluten washed out in the ordinary way 
must end in failure, since the properties of washed gluten depend upon 
the electrolytes which happen to be left in after the washing is concluded. 
Electrolytes—that is to say salts, acids and alkalis—intervene in two 
absolutely distinct ways. They control the physical properties of the gluten 
in the dough, and they must also profoundly modify the temperature rela- 
tions and the rapidity of the change undergone by the gluten and other 
constituents of the dough in the process of baking—a change which, so far 
as the proteins are concerned, is, broadly speaking, a lowering of solubility. 
We know something of the way in which they act on gluten in the dough, 
but of the more complicated action during temperature changes we know 
nothing ; it is possible that the same electrolyte may increase the mechanical 
stability of the loaf in the dough and yet diminish it in the oven. 
Let us turn to the action of electrolytes upon moist gluten, that is, upon 
gluten as it exists in dough. 
Gluten prepared from wheat by washing the flour in many changes of 
water is a stringy ductile body capable of retaining bubbles of gas. When 
it is placed in dilute acid or alkali this property vanishes. As little as 
1 part of sulphuric or hydrochloric acid in 20,000, or 1 in 5,000 of acetic 
or lactic acid, will disperse the gluten in fine particles. There is not only 
the loss of actual cohesion; the gluten particles are so changed that they 
actually repel one another and a non-settling milky suspension is produced. 
In order to restore cohesion it is merely necessary either to neutralise the 
acid or to add any salt such as common table salt. 
Any salt confers cohesion upon gluten; any acid or alkali when suffi- 
ciently dilute lessens or destroys it. Gluten itself seems to be purely 
passive. 
The removal of salts by washing gluten with distilled water will lower 
the forces which make for cohesion, so that less and less acid is needed to 
neutralise them; a point may be reached where apparently any concentra- 
tion of acid, no matter how low, is sufficient. When gluten is thoroughly 
extracted with distilled water it loses cohesion and disperses as a cloud, 
not owing to the action of the water but because of the faint acidity due to 
the carbonic acid dissolved from the air. This can be proved in many ways, 
most directly perhaps by the fact that careful neutralisation of the carbonic 
acid will restore cohesion. A brief but more detailed consideration of the 
action of acids, alkalis and salts is needed to make these points clear. 
Action of Acids and Alkalis.—Acids and alkalis produce the same 
physical effects, but the latter also induce hydrolytic decomposition of the 
gluten. The effect of acids is therefore more easily followed, and for 
simplicity I propose to confine my remarks to them. 
Gluten prepared in the ordinary way and immersed in distilled water 
retains its cohesion unless measures be taken to wash out the salt which it 
contains. In N/1000 of any strong acid cohesion breaks down and the 
change is more rapid as the concentration of acid is increased up to about 
N/30. Further increase in concentration slows the rate of disintegration, 
until at N/12 for hydrochloric acid, N/25 for sulphuric acid and 1°75 N for 
phosphoric acid the gluten again becomes permanently coherent and more 
tenacious and less ductile than in its original state. Weak acids, such as 
oxalic, acetic, lactic, citric and tartaric acids, produce disintegration in 
dilute solution but fail to maintain cohesion even at very high concentration. 
When salt is added to gluten which has lost cohesion owing to the action 
of acid this property is restored, but the concentration of salt needed to 
undo or prevent the action of the acid varies with the concentration of the 
acid in a remarkable and characteristic manner. The relations can be best 
explained by reference to the curve. The ordinates are concentration of 
1909. 3E 
