PART IV. 



PBESERVATION AND STORAGE. 



As is well known, dried and bagged hops kept for some time 

 in contact with the air lose their colour and aroma at a 

 comparatively rapid rate, and often assume an unpleasant 

 odour, whereby their value for brewing purposes may be 

 entirely ruined. The rate of depreciation increases in pro- 

 portion as the hops have been bagged in a more moist 

 condition and kept in warm, damp apartments ; whilst, on 

 the other hand, their tendency to go bad may be retarded 

 (though not eradicated) by careful drying and storage in cool, 

 dry rooms. A. Mohl discovered a bacterium (Micrococcus 

 humuli Launensis) which he regarded as the cause of 

 deterioration in hops during storage. He looked upon this 

 organism as a generator of trimethylamine, the amine base 

 almost invariably detected in old hops. Kny and others 

 have, however, demonstrated the non-existence of such a 

 bacterium ; and further researches have shown that in the 

 great majority of cases the deterioration of hops is connected 

 with spontaneous heating. 



Behrens was inclined to regard as the cause of spon- 

 taneous heating a bacterium which he named Bacillus 

 lupuliperda,^ but subsequently altered his opinion, and con- 

 firmed that the organism in question was merely an 



I Dr. J. Behrens, Studien Uber die Conservirung und Zusammensetzung 

 des Hopfens, Berlin, 1896. 



