FERMENTED FOODS AND DRINKS 



215 



at 10 C. and are killed at a temperature above 35 C. The 

 so-called mother of vinegar consists of an agglutinated mass of 

 Mycoderma aceti and is used as a starter in the manufacture of 

 vinegar. Thus far it has not been possible to isolate the vinegar 

 ferment or enzyme from the living cells which form it. 



There are also acids of nonalcoholic origin formed by living 

 ferments, such as oxalic acid, malic acid, citric acid and others, 



FIG. 72. Types of yeast organisms and yeast sporulation. A, Saccharomyces 

 pasteurianus showing spore formation in fours and eights (after Bioletti); B, 

 Schizosaccharomyces octosporus, showing simple septation instead of budding, and 

 spore formation (after Schionning); C, Saccharomyces anomalus, vegetative cells 

 and spore sacs. (Marshall, after Kayser.} 



which appear to be derived from the direct fermentation of 

 sugars. Citric acid is formed from sugars through the activity 

 of two fungi, Citromyces pfefferianus and C. glaber. Saccharo- 

 myces hansenii forms oxalic acid from mannit and galactose, with- 

 out the intermediary alcohol formation. 



The following are the more important products in which 

 there is alcohol formation through the action of yeast organisms. 



