1906.] Alcoholic Fermentation in Cider. 245^ 



It is the presence of these ethers which determines largely the 

 flavour of the mature cider. 



It may be mentioned here that there are a large number of 

 different varieties of yeasts, as distinct from one another in 

 character as are, for example, different varieties of apples. The 

 nature of the fermentations produced by these different kinds 

 varies very considerably, particularly in the amounts of alcohol^ 

 glycerine, acids, and ethers formed. Consequently each kind of 

 yeast produces a characteristic flavour, some pleasant and others 

 unpleasant. It is, therefore, a matter of importance that cider 

 fermentations should be conducted by yeasts of a desirable 

 nature. 



From a purely practical point of view, there are a few points 

 which should be noted in connection with alcoholic fermentation. 

 It has been stated above that as fermentation proceeds, many of 

 the yeast plants become worn out and sink to the bottom of the 

 liquid to form the lees. In course of time a considerable 

 amount of decomposition takes place, and the products of decay 

 are liable to give a taint to the cider. To avoid this, cider 

 should never be allowed to remain on the lees for any consider- 

 able period of time ; it should be racked off carefully into a. 

 clean barrel. Where possible, racking should be done by means 

 of a syphon, for the reason that cider is disturbed less by a 

 syphon than by pumping or drawing-off into pails. Conse- 

 quently, the sediment is not stirred up, and comparatively little 

 of the carbonic acid gas, which is held in solution in the liquor, 

 is lost, since exposure to air is reduced to a minimum. It is 

 important that as much carbonic acid gas as possible should be 

 retained in the cider when active fermentation has ceased, on 

 account of this gas acting as a natural preservative against 

 many kinds of germs, which are extremely liable to produce 

 disorders in the cider. For example, a cider in which fer- 

 mentation has completely stopped, if deprived of carbonic acid 

 gas by filtering or racking with exposure to air, will frequently 

 turn sour owing to the action of the vinegar ferment, even 

 though the cask containing it may be filled to the bung-hole, 

 tightly bunged and comparatively air-tight. Therefore it is 

 best to place the cider in the store-cask shortly before fer- 

 mentation entirely ceases, so that it may become charged with 



