53° MICROBIOLOGY OF SPECIAL INDUSTEIES 



MISCELLANEOUS ALCOHOLIC BEVERAGES 

 CiDEK AND Perry 



These beverages are made by the alcoholic fermentation of the 

 juices of apples and pears respectively and come next to wine and beer 

 in the quantities produced. 



The composition of the fruit varies very much according to the 

 variety, especially in the matters of acidity, tannin and pectic sub- 

 stances. The following analysis is that of a good cider apple: 



Sugar 167 . o g. per liter. 



Tannin 2 .4 g. per liter. 



Acidity (as sulphuric) i ■ 6 g. per liter. 



The pectic matters vary from 2 g. to 25 g. per liter but should not 

 be too high. Pears contain usually about the same amount of sugar 

 as apples, more tannin and much less pectic substances. 



The microorganisms occurring naturally on the surface of the fruit 

 are similar to those occurring on grapes, but special forms of Sac- 

 charomyces are found. Pure cultures of wine yeast are used success- 

 fully in cider making where a perfectly dry cider is wanted. Where a 

 small remnant of unfermented sugar is desired, the difficulties of using 

 pure cultures have not yet been overcome. The wild yeasts occurring 

 on the fruit in large quantities usually take precedence. 



Attempts to sterilize the juice by heating have not been successful 

 owing to the production of a persistent cloudiness. Sulphurous acid 

 is even more effective than in grape juice in delaying or preventing the 

 action of the microorganisms. Its use must therefore always be 

 supplemented by a starter of pure yeast. 



The principles of the control of the microorganisms, good and 

 bad, are the same as in wine making. The same care in gathering 

 and keeping the fruit and in extracting and handUng the juice are 

 necessary. 



, The fermentation is similar to that of wine, but the cider should be 

 taken off the yeast sooner in order to promote clarification and the 

 retention of a httle unfermented sugar. 



Cider is subject to the same bacterial alterations as wine and requires 

 the same treatment. It is more difficult to keep when made in the 

 ordinary way and is usually consumed during the first year. It is 



