PASTEUR'S THEORY 99 



tained. The reactions illustrating the cleavage of glucose according 

 to Neuberg's theory may be written as follows according to Euler 

 and Lindner: 



C 6 Hi 2 O 6 - 2 H 2 = C 6 H 8 4 (Metbylglyoxal-aldol) 



C 6 H 8 4 = 2 CH 2 :C(OH).COH or 2 CH 3 .CO.COH (Methyl- 



glyoxal) 

 CH 2 : C(OH) .COH + H 2 H 2 CH 2 OH-CHOH-CH 2 OH 



+ | = Glycerol 



CH 2 :C(OH).COH O CH 2 : C(OH).COOH 



Lactic acid 



CH 3 .CO.COOH = C0 2 + CH 3 .COH (Acetaldehyde) 

 CH 3 .CO.COH O CH 3 .CO.COOH (Lactic acid) 



I I 



CH 3 .COH H 2 CH 3 .CH 2 OH (Ethyl alcohol) 



Neuberg l has produced more evidence to support his aldehyde 

 theory of fermentation. By adding sodium sulfite, aldehyde and glyc- 

 erol were the chief products. 



Lob 2 has given the chemistry of alcoholic fermentation comprehen- 

 sive study. He has produced much evidence on the fact that aldehyde 

 is the important intermediate compound. He argues that the sugars 

 tend to cleave into the same substances from which they may be built 

 up. That aldehydes are intermediate in alcoholic fermentation has been 

 stated by many, but few have gone far enough to produce either 

 plausible evidence or experimental data to support their claims. 



Kusserow 3 proposed that glucose was first reduced to sorbitol and 

 this fermented. 



General Theories of Alcoholic Fermentation 



Alcoholic fermentation seems to have for its purpose the libera- 

 tion of the energy necessary in the life of the yeast when it finds 

 itself deprived of air under conditions in which respiration is not pos- 

 sible. This theory has not been accepted by all and it might be 

 well to mention some of the different theories which have been put 

 forth to explain this phenomenon. 



Pasteur's Theory 



Pasteur was the first to think that yeasts, when growing away 

 from air, might seek the oxygen, which they needed, in the com- 



1 Neuberg, C., and Reinfurth, E. Natural and forced glycerol formation in 

 alcoholic fermentation. Biochem. Zeit. 92, 234-66, 1918. Chem. Absts. 13 

 (1919), 2046. 



2 Lob, W. See bibliographical index. 



3 Kusserow, R. Eine neue Theorie der alkoholischen Garung. Cent. Bakt. 

 Abt. II., 26 (1910), 184-187. 



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