442 MICROBIOLOGY OF SPECIAL INDUSTRIES. 



HYDROMEL OR MEAD. 



An alcoholic beverage made by the fermentation of honey and water 

 is much used in eastern Europe. 



Honey contains from 65 to 74 per cent of reducing sugars and from 

 2 to 10 per cent of saccharose. It is diluted with water to reduce its 

 concentration to 22 BaL* to 24 Bal. A few yeast cells are usually present 

 in the honey but these are of various kinds and often unsuitable. The 

 use of a good pure yeast is therefore advisable. As honey contains little 

 mineral or nitrogenous yeast food, an addition of nutritive substances is 

 necessary. 



The following formulae are recommended by Kayser and Boullanger 

 to be used in one liter: 



A. Dicalcic phosphate i g. 



Ammonia 2 g. 



Bitartrate of potash 2 g. 



Magnesium sulphate o. i g. 



B. Maltopeptone i . 5 g. 



Bitartrate of potash i . 5 g. 



Ammonium phosphate * o g. 



The same results may be obtained by mixing from 20 to 50 per cent 

 of grape must or apple juice with the diluted honey. 



MISCELLANEOUS FERMENTED BEVERAGES. 



Fermented beverages of some kind are made in practically every part 

 of the world. They are very numerous and varied but fall naturally into 

 three groups; those made from the sweet juices of fruits or other plants in 

 which the methods of manufacture resemble those of wine making; those 

 made from starchy materials in which the methods resemble those of brew- 

 ing; and finally those made from the milk of cows or other mammals 

 which are discussed in Chapter IV, Div. IV. 



Belonging to the first group are numerous beverages made from the 

 juices of sugar cane, various palms, and tropical fruits. The best known of 

 these is the MEXICAN PULQUE made by the spontaneous fermentation of 

 the sweet juice of the agave. Little is known about the microflora con- 



* "Balling" refers to the special hydrometer for determining the specific gravity of fer- 

 mented alcoholic products as beer. Its purpose is to indicate directly the percentage of 

 solids in solution at a temperature of 63.5 F. . <- , 



