1 Jaw., 1900.] QUEENSLAND AGRICULTURAL JOURNAL. 33 
TEMPERATURE OF FERMENTATION, 
The temperature at which must ferments into wine exercises as much 
/ influence on the quality of the product as its acidity and other circumstances. 
| Both too low and too high a temperature are hurtful, but the former is hardly 
likely to occur in this colony; the latter, which is far more dangerous, is very 
ossible. 
The best temperature for must to ferment at is between 80 and 90 degrees, 
but up to 95 degrees the germs will still do their work, though more sluggishly ; 
if the temperature mounts higher, the ferment germs become paralysed, and the 
bacteria, which are ever present in fermenting hquids, get to work and more or 
less diminish its quality and soundness. On this point some of last year’s 
remarks are reproduced :— 
“Tet us examine for a moment how a high temperature affects the 
fermenting must. When grapes are crushed, the must is sown with the spores 
not only of the Saccharomyces ellipsoideus adhering to the skins, but also with 
the spores of the Mycoderma (or mildew), and the bacteria of lactic, acetic, and 
other fermentations. These latter may be adherent to the fermenting vats and 
other plant in use, or may be conveyed by the atmosphere. So long as the must 
is kept at a temperature favourable for the development and reproduction of the 
Saccharomyces, the inimical germs are, so to say, crowded out and their functions 
impeded. The sugar is transformed into alcohol and the other products of 
vinuous fermentation, and a good sound wine is the result. But as the tempera- 
ture mounts and the vitality of the Saccharomyces becomes weakened, the 
bacteria, which at first were unable to find room, begin to multiply, especially if 
the must is deficient in acidity. There arrives a point at which the work of the 
Saccharomyces ceases—they are either killed or paralysed: the must ceases to 
ferment. All this time the lactic and other germs, which can live and perform 
their functions in a much higher temperature than the Saccharomyces, are 
converting the sugar into lactic and acetic acids, with a more or less disastrous 
effect upon the quality and keeping powers of the wine. The Saccharomyces 
never properly resume their functions after the wine has cooled down, and it 
remains muddy with a sweet acid taste. Frequently, when too high a 
temperature has caused the collapse of the vinous fermentation, what is known 
as mannitic fermentation commences, which is the work of a bacteria which 
converts the sugar into mannitie and acetic acid. 
* % * % % 
"The cessation of the vinous fermentation, as described above, is known as 
‘stuck’ wine, and prompt measures must be taken if it is to be saved. The 
best way of proceeding is to rack off the wine into two or more vats, and to 
add to it an equal quantity of fresh must, if possible, in a fermenting condition ; 
if the fresh must is not fermenting, put into each vat several gallons of 
fermenting must from another source, so as to restore the vinous fermentation 
as quickly as possible, and not allow time for the lactic or other germs to get 
into play, at the same time cooling the vats as explained later on. 
“The good old proverb, * Prevention is better than cure,’ is applicable to 
many things in life, but to none more than to wine-making ; and if the vigneron 
neglects to bear it in mind, he will have to cogitate on another which says, 
‘What can’t be cured must be endured,’ so instead of having to tackle a 
‘Stuck’ vat, and spoiling wine, with all the attendant hurry scurry and anxiety, 
1t 1s better to take those precautions which will prevent it. 
COOLING ARRANGEMENTS. 
“Tf the weather is very hot, do not gather and crush the grapes during the 
heat of the day, but only in the morning, or, if gathered all day, leave them to 
cool for a night. 
_ “Avoid the use of too large-sized vats; those of 500 gallons capacity are 
quite large enough for a moderate-sized vineyard, and these can be kept cool 
by very simple means. Should the temperature within rise too high, vats of 
sarger size than this will probably require a cooling apparatus, unless in cool, 
c 
