3
Acidity often requires adjustment. If wine pH is above 3.45 just after crushing, it should be
corrected with tartaric acid. If grapes have soaked out 24 hours, the target pH is 3.60. A rule of
thumb is to add 2.0 grams of tartaric acid per anticipated gallon of wine for each 0.1 drop in pH
desired. If pH is below 3.45, don’t worry about it at this point. Deacidification may be
considered after fermentation.
The GOliner is a sterile container that permit control of the microbiological processes of
fermentation. It prevents contamination of the must (crushed grapes) from microorganisms
resident in the winery and cross-contamination from spoilage organisms from other batches
where they may have taken hold. However, each lot of grapes carries with it a substantial and
complex collection of mostly alcohol-intolerant wild yeasts and bacteria that sometimes create
undesirable prior to the onset of fermentation by your inoculum of commercial yeast. It is
conventional wisdom to suppress this activity by adding a small amount of sulfur dioxide at
crushing. For sound grapes, use a teaspoon of potassium metabisulfite (KMBS) for each 200
pounds, sprinkled in slowly at the crusher to obtain good mixing. The GOfermentor will do the
rest.
After additions, the exhaust vent is attached and in the inlet port closed. The fermentation will
now proceed and the GOliner will inflate with CO2. The punch schedule can be set and punches
started after 24 to 48 hours. Samples should be taken to determine the end of fermentation
(typically when all the sugar has been consumed). The easiest way to take samples is to use the
GOtemp sampling tube option.
A red wine fermentation proceeds hotter than white wines (next section) and ideally peaks
above 80oF for good extraction and color stability. While cooling is not essential for red wines,
you may find, depending on the room’s temperature and the grape load, that you are running
too hot (more than 90 oF). To control temperature pre-install a GOcooler heat exchanger
plate/control valve option. The GOtemp probe monitors fermentation temperature
automatically regulates the coolant supply valve to maintain the desired temperature setpoint.
The GOcooler plate is installed by placing it under the GOliner in the GOBase prior to filling. You
need to provide a pressurized source of circulating chilled water or glycol.
Pressing:
When the fermentation is complete the clean wine must be pressed out leaving the waste skins
and seeds (pomace) behind. Traditionally pressing is done by transferring the fermented must
to a dedicated press. These presses cost between $ 3000 to $ 20,000. In addition to the cost,
they require tedious cleaning and maintenance. In contrast, The GOfermentor does NOT need
any external press. Pressing is done in the GOliner itself, eliminating the cost of a press and
required labor and washing.
