ROPINESS IN WORT AKD BEER. 285 



Ropiness in tan liquors is a phenomenon both well known 

 and unwelcome to the tanner, to whom it causes considerable 

 damage and loss, since not only is the liquor rendered worthless, 

 but the hides steeped in it also suffer owing to the masses of mucus 

 adhering so firmly to the leather that great difficulty is experienced 

 in getting them off again. This mucinous coating retards, or even 

 entirely prevents, the penetration of the tannin. Closer investiga- 

 tions regarding the best means and methods of prevention would 

 be valuable to this industry. 



166. Ropiness in Wort and Beer. 



PASTEUR (III.) was the first to study this phenomenon with 

 the aid of the microscope. He traced the cause of this complaint, 

 which has many points in common with ropiness in wine, to a 

 fission fungus occurring abundantly in the form of long chains 

 in the affected liquids, and known by the name of Micrococcus 

 viscosus. Morphologically, this organism greatly resembles a fission 

 fungus observed by J. BERSCH (II.) in a beer wort, which, instead 

 of fermenting normally when pitched with yeast, became thick, 

 oily, and finally viscid and ropy. 



P. LINDNER (III.) in 1889 was the first to obtain a pure 

 culture of a viscous ferment. This was a pediococcus (not specifi- 

 cally named) occurring in large numbers in ropy white beers, a 

 class of beverage that is particularly liable to the malady. The 

 capacities of the microbe in question are restricted to the pro- 

 duction of ropiness in white beer wort, it being unable to do so 

 in hopped worts and beers. Hence it is perfectly innocuous and 

 unimportant, so far as true brewing, in the narrow sense of the 

 term, is concerned. 



Other species appear in hopped beer. Two of these were 

 found by H. VAN LAER (II.) in a number of samples of ropy beer, 

 from which they were isolated to pure cultures, and named 

 Bacillus viscosus I. and //. Both have several identical char- 

 acteristics, e.g. the form and dimensions of the cells, which are 

 rod-shaped, 0.8 p broad, 1.6-2.4 p l n g> an( i mostly single, though 

 not infrequently joined in pairs. 



In their behaviour towards beer-wort, however, they differ in 

 a notable manner. It is true that both of them produce ropiness, 

 but not of the same type. If B. v. I. is in action, then, in pro- 

 portion as the viscidity of the liquid increases, a number of 

 mucinous, yellowish- white patches, terminating below in branches, 

 appear on the surface. In this way a coating of mucus is formed, 

 the surface of which is gradually covered with protuberances pro- 

 duced by bubbles of the carbon dioxide liberated during this 

 fermentation. With B. v. II., on the contrary, this coating is 

 absent ; moreover, the evolution of carbon dioxide is less copious, 

 and the ultimate degree of ropiness less pronounced than in the 



