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THE GUM FERMENTATION OF SUGAR CANE JUICE. 



By R. Greig Smith, M.Sc, Macleay Bacteriologist 

 TO THE Society. 



(Plate XXX.) 



During the process of manufacturing sugar in the cane-mills, 

 the juice frequently becomes more or less viscous or "gummy," 

 and when this takes place the crystallisation of the sugar is con- 

 siderably hindered. The "gumming" may occur in the cane 

 juice — the immediate product of the crushed cane — or it may 

 develop at any stage in the manufacture of the raw sugar, 

 especially if the juice or syrup is allowed to cool, or to stand for 

 any length of time. Experience has shown that the only way to 

 minimise the trouble is to complete the crystallisation of the 

 sugar as quickly as possible. The cause of the formation of the 

 gum is not definitely known, although the prevailing idea is that 

 it is developed from something which is contained in the juice. 



I received two samples of gummed cane juice from Mr. T. Steel 

 of the Colonial Sugar Company, and was at the same time 

 informed that any information regarding the properties of micro- 

 organisms, which might induce the gummy fermentation of sugar, 

 would be of the greatest economic importance to the sugar 

 manufacturers. Each of the samples consisted of about 5 c.c. of 

 roller cane juice, which had not been treated in any way. One 

 of the samples was viscid ; the other appeared limpid, but I was 

 informed that, as compared with normal cane juice, it was 

 decidedly gummy. 



The Separation of the Gum-forming Organism. 



From the samples several organisms were separated, but none 

 of them produced any apparent viscosity in solutions containing 



