ZYMOLOGY FERMENTS AND FERMENTATIONS 233 



process of fermentation, several organisms are active, along with A. 

 oryza, as Saccharomyces soya, Bacillus soya and Sarcina hamayuchia. 



Mazun. This, like kephir and koumiss, is fermented milk, usually 

 of the cow and goat, and is much used in Armenia. The active organisms 

 are a yeast, a bacillus apparently identical with B. subtilis and several 

 lactic acid bacteria. 



Leban. This sour, aromatic drink, is closely similar tomazun and is 

 made from boilt buffalo's, cow's and goat's milk, in Egypt. It is said to 

 contain less alcohol than kephir. Five different organisms, evidently 

 mutualistically associated, are active in Leban fermentation; a Strepto- 

 coccus which coagulates milk and forms lactic acid from lactose, another 

 bacillus, a Diplococcus which ferments glucose, saccharose and maltose; a 

 streptococcus which hydrolyzes lactose and another yeast organism 

 which can ferment glucose and maltose but not lactose. 



Ginger Beer. This is a fermented sugar solution to which ginger -is 

 added. The essential fermenting organisms are a Saccharomyces 

 (S. pyriformis) and Bacillus vermiforme. Mycoderma aceti is also present. 

 The two essential organisms are evidently in close mutualistic relation- 

 ship. The drink resulting from the fermentation of saccharine solution 

 is acid and effervescing. The so-called "ginger beer plant" which is 

 simply a mass or matrix of the active organisms is used to start a new 

 fermentation. 



6. Cider Making 



Acetic-acid fermentation in wine cider and other fermented alcoholic 

 substances is initiated by the Mycoderma aceti, collectively known as 

 " mother of vinegar." This is no doubt a mixed growth, representing 

 several species or varieties of acetic-acid forming organisms. While 

 it is true that nature invariably inoculates the substances named, re- 

 sulting in the production of vinegar, it is customary to use the top skin 

 or pellicle (mother of vinegar) on vinegar already formed, adding it to 

 new wine or cider in order to hasten the fermentation. As stated, this 

 is not a pure culture representing a single species. In fact, the tests 

 with what were pure species have proven unsatisfactory. The vinegar 

 organisms require an abundance of oyxgen. To supply the necessary 

 oxygen (of the air) it is customary to have the fermentation barrels or 

 casks only about two-thirds or three-fourths full and to leave the bunghole 

 open (generally with a plug of cotton). In Germany a quickened 

 method is much in vogue. The wine or cider is allowed to trickle slowly 

 through a cask filled with wood shavings which are moistened with old 

 vinegar. The wood shavings offer a maximum surface exposure and 

 fermentation is as a result very much hastened. 



