566 CHAPTER XXVIII 



influence of certain well-defined bacteria or under that of an imperfect 

 fungus, referred to as Mycoderma vini ; generally it is essentially a process 

 of oxidation, but Watts and Tempany have shown that the spontaneous 

 souring of cane juice proceeds anaerobically, the sugar forming the source 

 of oxygen. Acetic acid has been observed by Greig Smith^^ in soured sugar, 

 and sugar or juices left in crevices about a sugar factory undergo this fer- 

 mentation and are responsible for the sour smell often observed ; wash kept 

 after the alcoholic fermentation is complete also undergoes acetic fermenta- 

 tion, and the writer has knowledge of cases where consignments of " molas- 

 cuit " completely underwent this fermentation in transit between Demerara 

 and London. 



Butyric Acid Fermentation. — This fermentation is technically of import- 

 ance in the rum industry as the flavour of fine rum is by some authorities 

 believed to be intimately connected with its presence ; in cereal distilleries 

 it is considered most hai"mful, as not only does it decrease the yield of alcohol, 

 but also forms objectionable products as butyric acid and butyl alcohol. 



Viscous Fermentation. — This term has now only an ill-defined meaning, 

 but occurs frequently in older writings on fermentation ; it is used in refer- 

 ence to fermenting liquids becoming ropy or slimy, and was once not an 

 uncommon phenomenon. In European distilleries this disease has been 

 associated with certain well-defined bacterial species ; in rum distilleries 

 it is not unknown, and may often be traced to lack of cleanliness and to 

 attempting to work with too little or no bactericide. 



Gumming. — The " gumming " of cane juices has been studied by Greig 

 Smith^2 ^jjQ found that this was due to a bacillus which he described, and 

 named Bacillus levaniformans ; this organism is also one of several respon- 

 sible for the deterioration of sugars. Lewton Brain and Deerr^^ isolated from 

 Hawaiian sugars several forms which also produced large quantities of gum. 

 Formerly this fermentation would have been classed as a " viscous fer- 

 mentation." 



Leuconostoc mesenteroides. — This organism, known as " frog spawn," 

 has the faculty of converting sugar solutions into a gelatinous, viscous 

 mass. It is a well-known type and has been reported from Europe and 

 Java where it has been the cause of blocking up pipes used for the convey- 

 ance of juices. It a'so occurs in Hawaii and Cuba. An alkaline reaction 

 favours its development, and therefore " liming " does not prevent, but aids, 

 its growth. In recent literature this organism is classed as a Streptococcus. 



Spontaneous Fermentation of Cane Juice. — Watts and Tempany^^ found 

 that yeasts and an undetermined bacterium were concerned in this process. 

 Alcohol was produced by the yeast, and acids by the bacterium, of which 

 about one-third were volatile acids. The fermentation was both aerobic 

 and anaerobic, and was inhibited by the presence of phenol, indicating that 

 already formed enzymes do not play a very prominent part in the souring of 

 juices. 



Spontaneous Combustion of Molasses. — Crawley^^ has recorded a case 

 of molasses on storage becoming charred, the damage being supposed to 

 have been initially due to micro-organisms ; consignments of " molascuit " 

 have suffered a similar change on board ship. 



Nitric Fermentation of Molasses. — In beet sugar factories the after- 

 massecuites on storing sometimes show a nitric fermentation. A dense 



