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 MucoracecB 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 KohP ; 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, Schizosaccharomycetes. This includes one genus, 

 Schizosaccharomyces. 



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

 I. Torula ; 2. Mycoderma ; 3. Monilia ; 4. Chalara ; 5. Oidium ; 6. Dema- 

 tium ; 7. Sachsia ; 8. Endomyces ; g. 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 cerevisicB, of which a number of varieties or races 

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

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



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