Home winemaking strategies for keeping white ferments cool

There is general agreement that white juice should be fermented at cool temperatures, taking several weeks to complete the process rather than the several days common with red must.

Keeping white ferments cool is particularly applicable for the aromatic style. The cooler ferments can yield better varietal fruit flavor. 10-15ºC is usually the target (check the recommendation for your yeast), but some members report fermenting at close to 5ºC (at least part of the time), with ice in their airlocks! Yeast cells can’t do much at 5ºC but they won’t die either. Commercial wineries can use jacket-cooled tanks to achieve the desire temperature. Here are some of the strategies of Club members for the home winemaker.

No matter how cool you do most of your ferment, it is wise to bring it back to about 20ºC to finish the fermentation. You make this adjustment at a specific gravity close to 1.000.

Some cooling options used by club members

1. Wait for cooler outdoor temperatures and ferment outside in the shade or in an uninsulated room. The problem is that outdoor temperatures are variable, but this is a cost-effective strategy and can be used in conjunction with ice packs (see number 3).
2. Use a cold water bath. Keep your fermenter in a larger vessel in which you circulate cooler water. One club member circulates a stream of steady-temperature well water around his fermenter, with the well water then moving to a cistern for later reuse. You could also run a clean (and alcohol resistant) length of garden hose in coils through the ferment.
3. Use ice packs. Keep a selection of ice packs (you can use 1L and 2L pop bottles, with paper and markings removed) in your freezer. Regularly add one to the ferment to keep the temperature down.
4. Use an old fridge or cooler. Make sure the thermostat will manage the temperature range you want.
5. Build a small room with its own air conditioner and rig a thermostat. This is the most elegant and adaptable solution. Ambient room air temperature will need to be less than your desired fermentation temperature.

WARNING: CO₂ will build up inside any small room or cooler user for fermentation. Be careful.