the ]\[aldiu/ of Cider and Pcrrij. 
399 
It is material to notice this increase of the saccharine matter, and 
.the decrease of gluten, or fermentive principle, as the a])ple ad- 
vances to perfect ripeness, as these circumstances exercise a most 
important influence in the manufacture of cider. When apples 
fall from the tree, though ripe in the common acceptation of the 
word, they are not arrived at that maturity necessary to the pro- 
duction of the best quality of cider, or rather of that cider which 
is most generally desired, and which possesses an agreeable com- 
bination of sweetness, acidity, and spirit. If the juice be ex- 
pressed from the fruit out' of contact with the air, it may be kept 
for any length of time in a close-stopped vessel without under- 
going any change ; but as soon as air is admitted the liquor be- 
comes turbid, and begins to ferment.* It is in this way that fer- 
mentation is prevented in the fruit, the air being excluded by the 
comjiact rind of the fruit; but no sooner is this coat and the cells 
of the apple broken by bruising than fermentation commences, 
the lluid l)ecomes brown, and decay of the fruit ensues. 
W hen the juice is expressed from the fruit in the ordinary way 
for making cider, and placed in a tub or cask, exposed to the air 
at an ordinary temperature, it soon becomes turbid, enlarges in 
volume from being full of minute bubbles, which rise to the sur- 
face, bearing with them a scum, while a sediment falls to the 
bottom of the vessel. This is the action of fermentation. The 
change thus going on was commenced by the oxygen of the air 
uniting with the gluten of the juice, which thus becomes a fer- 
ment — that is, o[lulen in a state of change from a soluble to an 
insoluble substance, and is strictly of the same nature as yeast. 
In this state it becomes an exciter of change in the susjar, causine: 
its elements to undergo new arrangements, by which they form 
alcohol, or spirit, which remains in the liquor, and carbonic acid, 
which escapes as gas. This change, if unchecked, will often 
proceed until all the sugar disappears, and the cider becomes 
harsh. If, instead of a deep tub or cask, the juice be placed in 
a shallow vessel, and kept at a low temperature, the gluten is then 
oxydized and precipitated, producing only a modified action on the 
sugar, owing to the low temperature, by which the latter under- 
goes a more gradual change. By the precipitation of the gluten 
thus produced the liquor is prevented from undergoing strong 
fermentation when put into the cask. It is this action of the air 
upon the gluten by which the latter is thrown down, that cider- 
makers avail themselves of when they wish to subdue or prevent 
excessive or violent fermentation. 
If, as soon as they fall, the apples be immediately carried to 
the mill and crushed for cider, the juice drawn from them will be 
VOL. IV. 
* Gay Lussac. 
2d 
