SOFT EESINS IN" SULPHURED AND UNSULPHURED HOPS. 



9 



hops. A further study of Table V indicates that a combination of 

 sulphuring and cold storage was most effective in retarding the 

 changes that produce hard resins. 



TOTAL RESINS. 



The total resin content of the various hop samples, found by adding 

 the soft resins and the hard resins together, is shown in Table AT. 



Table VI. — Total resins in the original samples of sulphured and unsulphured hops 

 and in samples kept in cold and in open storage. 



Treatment at the kiln. 



Original 



sample, 



1911. 



Cold storage. 



Open storage. 



Sulphured 



Unsulphured. 



Per ant. 

 17.58 

 17.60 



Per cent. 

 18.44 

 IS. 07 



Per cent. 

 20.43 



IS. 74 



Per cent. 

 14.88 

 13.36 



Per cent. 



' 19. 64 



18.26 



Per cent. 

 18.12 

 17.88 



Per cent. 

 13.30 



12.78 



From the figures in Table VI it appears that some discrepancies 

 exist, since the total resins in some years ran higher than those of 

 the original sample. Experiments in this laboratory have shown that 

 two samples are rarely ever the same in total yield of resins ; hence, no 

 weight need be attached to the apparent discrepancies. 



The sudden decrease in the total resins in all the samples in the 

 year 1914 is of special interest. Up to this point the hops in storage 

 had retained approximately their original content of soft resins. A 

 marked diminution now .occurred in the content of soft resins, which 

 is not compensated by a corresponding increase in the content of 

 hard resins. It appears from the data at hand that a portion of 

 the soft resins had been transformed into a compound or compounds 

 insoluble in ether or in petroleum ether, since the marked loss in 

 percentage of soft resins does not appear in the ether extract. The 

 extent of the change was greatest in the unsulphured hops in open 

 storage and least in the sulphured hops in cold storage, but in all 

 samples, irrespective of treatment either at the kiln or during storage, 

 the decrease was rapid. Table IV shows that at the end of the second 

 year of storage a point was reached by all the samples beyond which 

 the hard resins did not materially increase. Nevertheless, at this 

 point the soft resins began to decrease most rapidly. Although pre- 

 vious investigators have stated that the soft resins change entirely 

 to hard resins, it is probable that only a small portion of the soft 

 resins undergoes such a change, and the remainder is changed into a. 

 compound or compounds insoluble in the solvents used in extraction 

 and for that reason is lost sight of in the analysis. 

 98657°— Bull. 282—15 2 



