CHAPTER XXVIII 



FERMENTATION WITH SPECIAL REFERENCE TO THE 

 SUGAR HOUSE 



THIS chapter treats principally of the fermentation of molasses and of the 

 manufacture of rum ; incidentally, opportunity is taken to bring together 

 some part of the scattered articles dealing with the mycology of the sugar 

 house. 



Yeast. By this term is loosely meant any organism which has the 

 property of fermenting sugars and producing mainly alcohol and carbon 

 dioxide ; in this sense organisms such as the Torulce, Monilia, and certain 

 of the Mucoracece would be included, although these organisms are very 

 distinct from that mainly composing " brewers' yeast," which consists 

 essentially of Saccharomyces cerevisice. Systematically, production of alcohol 

 is not an essential character of the Saccharomyces although the greater 

 number of species here included do produce alcohol ; in addition some species 

 ferment saccharose, glucose, fructose and maltose ; others glucose, fructose 

 and maltose only ; others lactose only. 



A complete list of all the known " yeasts " is given by Kohl 1 ; following 

 him they are divided into these groups : 



I. Yeasts proper or budding yeasts. Saccharomycetes. These are 

 divided into the following genera : I. Saccharomyces ; 2. Hansenia ; 

 3. Torulaspora ; 4. Zygosaccharomyces ; 5. Saccharomy codes ; 6. Sac- 

 charomycopsis ; 7. Pichia ; 8. Willia. 



II. Fission Yeasts, Schizo saccharomycetes. This includes one genus, 

 Schizosaccharomyces. 



III. Yeast-like fungi. These are divided into the following genera : 

 I. Torula ; 2. My coder ma ; 3. Monilia ; 4. Chalara ; 5. Oidium ; 6. Dema- 

 tium ; 7. Sachsia ; 8. Endomyces ; 9. Monospora ; 10. Nematospora. 



In rather a loose way yeast as it appears in breweries and distilleries is 

 classed as " top " yeast or " bottom " yeast, or otherwise as " high " and 

 " low " yeast. These terms refer to the behaviour during fermentation, 

 some races rising to the surface and others falling down as a sediment. 

 The difference is not specific, since a top race can be cultivated from a bottom 

 type, and vice versa. 



In breweries and distilleries generally, the production of alcohol is due to 

 the species Saccharomyces cerevisia, of which a number of varieties or races 

 are known. Went and Geerligs 2 in Java examined the budding yeast there 

 in arrack distilleries, and described it as a new species, 5. vordermanii, although 



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