




SOFT RESINS 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 VI. 
TaBLe VI.—Total resins in the original samples of sulphured and unsulphured hops 
and in samples kepi in cold and in open storage. 


ae Cold storage. Open storage. 
Original 
Treatment at the kiln. sample, 
eee 1912 1913 1914 1912 1913 i914 
: Per cent. | Per cent..| Per cent. | Per cent. | Per cent. | Per cent. | Per cent. 
Sulphured@enscseereee sas ee 17. 58 18. 44 20. 43 14. 88 19. 64 18. 12 13. 30 
Winswilphured esas see een 17. 60 18. 07 18. 74 13. 86 18. 26 17. 88 12. 78 

From the figures in Table VI it appears that some discrepancies 
exist, smce 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 retamed approximately their origmal 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 resms. 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 
pomt 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 
