May 20, 1918 



Hydration Capacity of Gluten 



411 



stant more nearly like that of oxalic than like those of acetic or lactic 

 acids. 



At first glance, leaving the phosphoric-acid graphs out of consideration, 

 it would appear that the amount of imbibition might be regulated solely 

 by the hydrogen-ion concentration, but when we take into considera- 

 tion the data for both phosphoric and boric acids, one of which is a rela- 

 tively strong acid but which nevertheless produces the form of imbibi- 

 tion curve typical of much weaker acids and the other a very weak acid 

 which produces no appreciable change in the degree of imbibition of the 

 glutens, it becomes more and more improbable that the hydrogen-ion 

 concentration is the only factor involved. Fischer (4, p. 44) has already 

 come to a similar conclusion while studying the imbibition of water by 

 animal proteins or tissues in solutions of acids, for he found that a "strong" 



Ac/o'*OOOSA/ /y^C/, 



^ co/v<r£/V7-/?/\r/OA/ o/^ ac/o 



'. — Graph showing the unbibition curves for Ws gluten in hydrochloric acid and in hydrochloric acid 



plus certain salts. 



acid (hydrochloric) stands at the top of the list, another (sulphuric) 

 stands at the very bottom, while a series of "weak" organic acids are 

 found between. 



Jessen-Hansen (/o) has made an extensive study as to the relationship 

 between the hydrogen-ion concentration of the flour and the volume 

 and quality of the resulting loaf. He finds that there is an optimum 

 hydrogen-ion concentration of about P= h5- I^or strong flours the 

 optimum may slightly exceed this, and for poor flours it should be some- 

 what less. Whether or not the beneficial effects of this optimum hydro- 

 gen-ion concentration are due to the influence of the hydrogen ion on 

 water imbibition by the gluten or to the securing of the proper reaction 

 of the medium for the optimum growth of the yeast and zymase activity 

 is a problem for further investigation. It is probable, however, that 

 it is the latter factors which are principally influenced. 



