106 THE PROTEINS OF THE; WHEAT KERNEL. 



The results obtained by the author and described in this paper have led 

 to the conclusion that no ferment-action is involved in the formation of 

 gluten ; that but two protein substances are contained in the gluten, glu- 

 tenin and gliadin, and that these exist in the wheat kernel in the same 

 form as in the gluten, except that in the latter they are combined with 

 water in an amount equal to about twice the weight of the dried protein. 

 The reasons for this opinion are, first, that alcohol extracts the same protein 

 and in the same amount, whether applied directly to the flour, to the gluten, 

 or to flour previously extracted with 10 per cent sodium-chloride solution ; 

 second, that 0.2 per cent potassium-hydroxide solution extracts glutenin of 

 uniform composition and properties from flour which has been extracted with 

 alcohol or with 10 per cent sodium -chloride brine and then with alcohol as 

 it extracts from gluten which has been exhausted with alcohol. 



Both glutenin and gliadin are necessary for the formation of gluten, 

 as may be seen from the following experiments : A portion of flour was 

 washed completely free from gliadin by means of alcohol of o. 90 sp. gr. , 

 next with stronger alcohol, finally with absolute alcohol, and air-dried. 

 The residue was then rubbed up fine until all lumps were removed, and 

 water carefully added and a dough made of the mass. A tolerably coherent 

 dough was thus obtained, but much less elastic and tough than that pro- 

 duced from the untreated flour. This dough was then washed with water 

 on a sieve, using every precaution to obtain a gluten, but none was formed. 



In another experiment 7.5 grams of very finely ground air-dried gliadin 

 were mixed intimately with 70 grams of fine corn-starch and distilled water 

 added. A plastic dough was thus produced, but it had no toughness. On 

 adding a little 10 per cent sodium-chloride solution, the dough became at 

 once tough and elastic. This was then washed with great care on a sieve 

 with cold water, a little 10 per cent sodium-chloride solution being added 

 from time to time, but in spite of every precaution no gluten was obtained. 



The following experiment shows that the gliadin used was capable of 

 forming gluten when glutenin was present, and also that salts have a marked 

 influence on the toughness of the resulting dough. Two portions of flour 

 weighing 100 grams each were taken, and after adding 5 grams of gliadin to 

 one both were made into dough with the same quantity of water. The 

 two doughs presented marked differences. That to which gliadin had been 

 added was much tougher and more yellow than the other. They were then 

 washed with water as long as starch separated. The gluten was dried 

 superficially by wiping with a cloth and weighed in the moist state. That 

 from i oo grams of flour to which 5 grams of gliadin had been added weighed 

 44-55 grams ; that from 100 grams of flour alone weighed 27.65 grams. 

 The moist glutens were dried at 1 10 to constant weight, and both yielded 



