762 EXPERIMENT STATION RECORD. 



FOODS— HUMAN NUTRITION. 



The proteins of the wheat kernel, T. B. Osborne {Carnegie Inst. Washington 

 Puh. 8-'/, pp. 119). — The author suimnurizes available data on the nitrogenous 

 constituents of the wbeat kernel and reports a number of investigations on 

 the amount and cbaracteristies of these bodies and related questions. Quota- 

 tions from the author's summary follow : 



" The proteins of the wheat kernel are gliadin, insoluble in neutral aqueous 

 solutions, but distinguished from all the others by its ready solubility in neutral 

 70 per cent alcohol ; glutenin, a protein having a similar elementary percentage 

 composition to gliadin, soluble in very dilute acid and alkaline solutions, but 

 insoluble in dilute alcohol or neutral aqueous solutions and yielding a wholly 

 different proportion of decomposition products when boiled with strong acids ; 

 leucosin, an albumin-like protein, freely soluble in pure water and coagulated 

 by heating its solution to 50 to 60° ; a globulin similar in composition and 

 properties to many globulins found in other seeds, and one or more proteoses 

 which are pi-eseut in very small quantity. It has also been shown that the pro- 

 teins obtained from the embryo of the wheat are the globulin, albumin, and 

 proteose above mentioned, and that these form nearly all of the protein sub- 

 stance of this part of the seed. It thus appears that these three proteins are 

 contained chiefly in the embryo, and that gliadin and glutenin form nearly the 

 whole of the proteins of the endosperm, or over SO per cent of the total jirotein 

 matter of the seed. It is possible tliat a part of the albumin, globulin, and per- 

 haps minute quantities of the proteose are contained also in the endosiierm, 

 for these proteins are always found in flour froni which, in the milling process, 

 the embryo is very nearly completely separated. . . . 



" Gluten contains the greater part of the protein matter of the seed, together 

 with a little starch, fat, lecithin, and phytocholesterin, and possibly some carbo- 

 hydrate substance or substances of as yet unknown character. These nonprotein 

 substances are i)r()l)ably not united with one another in the gluten. Init are 

 uieclianically mixed. The quantity of starch that remains in the gluten depends 

 on the thoroughness of the washing, while the other substances owe their pres- 

 ence largely to their insolubility in water. The chief constituents of the gluten 

 are the two proteids, gliadin and glutenin, the relative proportions of which vary 

 with the variety of wheat from which the flour is made. The character of the 

 gluten and the commercial value of the flour depend to a large extent on the 

 proportion of gliadin to glutenin. 



" In the moist gluten these proteins are present combined with about twice 

 their weight of water, which is gradually lost on exposure to dry air or at an 

 elevated temperature. 



•> 'Y\^^^, <riiadin and glutenin are present as such in the seed and are not, as was 

 formerly supposed, derived from other protein substances through the action of 

 an enzym. This is shown by the fact that they may be obtained directly from 

 the flour by the same treatment as that which yields them from the gluten and 

 under conditions which i)reclude the action of an enzym." 



The characteristics of the different wheat constituents, the products which 

 they yield on hydrolysis, and I'elated questions are also considered and the 

 nutritive value of wheat gluten and other proteins is discussed on the basis of 

 the kind and amount of tlie cleavage ])roducts which they yield on hydrolysis. 



" The amount of glutaminic acid which the gluten proteins yield is far 

 greater than that yielded by any of the other food proteins, with tlie excepticm 

 of gliadin from rye and hordein from barley. The proteins of the legumes and 

 nuts which are used as food yield from 15 to 20 per cent of glutaminic acid, so 



