2 BULLETIN 282, TJ. S. DEPARTMENT OP AGRICULTURE. 



In order to obtain additional data regarding the effect of various 

 storage conditions upon the soft resins of sulphured and unsulphured 

 hops, a quantity of material was prepared and held under observa- 

 tion for several years. The data secured indicate that there is a 

 marked chemical rearrangement or balancing of at least a part of the 

 components of these resins during the first year after the hops are 

 harvested. This rearrangement is most marked in hops kept in cold 

 storage, and of these it is most evident in the unsulphured hops. 



It is generally conceded that the commercial value of hops is almost 

 entirely contingent upon two considerations, namely, the character 

 of the aroma and the nature and quantity of the soft resins. At the 

 last International Hop and Barley Exhibit, held in Chicago in 1911, 

 the score card gave an equal rating to aroma and to the soft resins, or, 

 as they are sometimes termed, the hop bitter acids. 



Although sulphuring and cold storage are efficient factors in retard- 

 ing the diminution of the quantity of soft resins in hops, they do not 

 prevent chemical changes from taking place therein. Nevertheless, 

 the data obtained by the study of these changes indicate that they 

 are influenced to a considerable degree by both sulphuring and cold 

 storage. The experiments detailed in the following pages were made 

 with a view to determining the extent and character of these changes. 



PREPARATION OF THE HOPS STUDIED. 



Since soil and climate, as well as other factors, are undoubtedly 

 responsible for the varying quantity of soft resins found in hops of 

 different geographical origin, all the samples of hops used in this 

 investigation were secured from a common source, hi order to elimi- 

 nate variation so far as possible. Accordingly, two lots of hops 

 harvested from the same field at Perkins, Cal., in September, 1911, 

 were dried in ordinary hop kilns, one portion without being sulphured, 

 the other receiving the customary sulphuring in the early stages of 

 drying. Duplicate samples of each lot were then placed in hermeti- 

 cally sealed tin cans and shipped to Washington, D. C. About the 

 1st of December one sample each of the sulphured and unsulphured 

 hops was subjected to analysis, and the remaining samples, each 

 weighing 2 kilograms, were then removed from the tins, compressed 

 to about the same degree as the hops in a commercial bale, and com- 

 pletely inclosed in a cover of ordinary hop sacking. Three each of 

 these sulphured and unsulphured samples were then placed in cold 

 storage in the hop storeroom of a loeal brewery, and a similar set of 

 samples was placed in the attic of a frame building at the Arlington 

 Experiment Farm, Virginia. On December 1 of each of the three fol- 

 lowing years one sample each of the sulphured and the unsulphured 

 hops was withdrawn from cold and open storage, respectively, and 

 subjected to analysis. 



