282 HOPS. 



per cent, of sulphuric acid and concentration, can be dissolved 

 in petroleum spirit, leaving the 7 resin as an insoluble re- 

 sidue.i Both the a and ^ resins are soluble in petroleum 

 ether, and have been termed the "soft resin" by Briant, 

 Meacham and others. When hops are extracted with ether 

 all three resins pass into solution, and the one insoluble in 

 petroleum spirit is knov^n as the "hard" (7) resin, and 

 considered as of no value in brev^ing (Behrens). Briant 

 and Meacham hold the opinion that the percentage of soft 

 resin is a measure of the quality of the hops, a view ap- 

 parently shared by Delbriick. They cite in support the 

 known fact that hops rich in soft resin behave better in 

 practice than those short of this constituent, and that during 

 storage, even when air is excluded, a portion of the soft 

 resin is gradually converted into the worthless 7 resin. 



Behrens,^ however, considers that to set up the content 

 of soft resin as a basis of quality is at least premature 

 since, whilst first-class hops contain 8'24 to 12'07 per cent., 

 second-class hops contain 8'90 to 11"22 per cent., and those 

 of third-class order 9'49 to 10'25 per cent., figures which 

 would appear to militate against the reliability of such an 

 assumption.^ 



The soft resins are only sparingly soluble in pure water, 

 but dissolve more readily in sugar solutions, and are ac- 

 credited with a certain antiseptic property, chiefly restricting- 

 lactic fermentation. In solution these resins are bitter, and 

 Hayduck therefore assumed them to constitute the bitter 

 principle of the hop. He also found that under repeated 



^ Leyser and Heiss, Die Bierbrauerei, Stuttgart, 1893. 



^ Zeitschrift fUr das gesammte Brauwesen, 1898. 



^ Keoently Dr. C. J. Lintner, who had elaborated a titrimetric method for 

 the estimation of the soft resin — bitter principle — in hops, showed that the 

 percentage varies between 7'04 and 14'62 per cent., according to the variety,, 

 Auscha green hops giving the lower value and Hallertau hops the higher 

 figures {Zeitschrift filr das gesamimte Brauwesen, 1898, No. 31). 



