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The Alcoholic Ferment of Yeast-juice. 



Summary. 



1. When glucose or fructose is added to yeast-juice in presence of excess of 

 phosphate, a period of accelerated fermentation occurs, during which the 

 added sugar undergoes the reaction : 



2C6Ha206 + 2P04HR2 = 2C02 + 2C2H60 + 2H20 + C6Hio04(P04R2)2, 

 one molecule of carbon dioxide being evolved for each molecule of sugar 

 added. 



2. When the available phosphate of a mixture of ferment, coferment, and 

 sugar is greatly reduced, the total fermentation produced becomes very small. 

 The addition of a small amount of a phosphate to such a mixture produces a 

 relatively large increase in the total fermentation, even after allowing for the 

 amount of carbon dioxide equivalent to the phosphate added. 



3. A hexosephosphate when digested with yeast-juice is hydrolysed by an 

 enzyme, hexosephosphatase, with production of free phosphate and a sugar 

 which is capable of being fermented by yeast. 



As the result of this hydrolytic action, the hexosephosphates, when treated 

 with yeast-juice or zymin, are finally converted into carbon dioxide, alcohol, 

 and free phosphate. 



4. In discussing the chemical changes which the molecule of sugar may 

 undergo in the process of fermentation, it is necessary to take into considera- 

 tion the,fact that two molecules of sugar are involved in the reaction. 



