Controlling Temperature for a White Fermentation

05/09/2012

Fermentation Temperature

Every winemaker has a theory on what temperature to ferment at.  We have seen great wine fermented from a variety of different temperature schedules. You should pay attention to the temperature. It's definitely a good habit to note the temperature of the must each time you stir the wine (a good way to do this is to use a fermometer (MT410)) for future reference. The act of fermentation produces heat and can cause the must to be 10°-15° F higher than the ambient temperature.  

A Typical Temperature Schedule  

If you have control over fermentation temperatures, a recommended white wine schedule is to start slowly and inoculate at slightly warmer temperatures, such as the low 60s. Then, once activity starts, gradually allow the must to cool down to the desired temperature as the fermentation gets underway (such as the mid to upper 50s). 

Yeast create different compounds at different temperatures. The general rule of thumb is that more esters are produced at higher temps, while more clarity of the fruit will be had at lower temps. However, this can also be strain dependent and there are no hard and fast rules. We encourage you to experiment with fermentation temperatures, but we do recommend staying within the tried-and-true 55°- 65° F range.
 
Controlling Temperature 

For white winemaking, the best ways to control fermentation temperatures are to either ferment in a space that already has cool ambient temps (a basement or cellar), or use some form of refrigeration to create cold (air conditioner or glycol system). Each option has advantages and  disadvantages:

1. Ambient cooling: Naturally occurring cool ambient temperatures as found in basements and cellars are great because they are free! However, you have no direct control over the temperature of the fermentation. If the fermentation temperatures start to run hot, you can make an ice bath for a smaller vessel.  For larger tanks, there is really nothing you can do about it.
   
   Watch out that the ice bath doesn't become too cold or you risk shocking the yeast and causing a stuck fermentation and H2S and VA production!
    
2. Air Conditioned Rooms: This is basically an ambient cooling system that you pay for. Air conditioning is a low-cost way to help keep fermentation temperatures low but you still have the same lack of temperature control at each fermenter if fermentation temperatures start to run away on you. As with any ambient cooling situation, air conditioning is more effective with smaller fermentation vessels.  
    
3. Refrigerator: If you are making a small amount of wine, a refrigerator or chest freezer can be used with a temperature controller (FE610) with great success. The nice thing about this set-up is that you can also cold-stabilize the wine, then set the temp back to maintain cellar temps for year round storage. The only downside is that you can only fit a small amount of wine into a fridge!
    
4. Glycol System: The most serious home hobbyist purchases a small glycol cooling system such as our GLY100 which can precisely dial in temperatures. They work by circulating cold water or water/glycol mix through a jacket around the tank or a cooling snake/cooling plate submerged in the fermenting must.  They are the best way to achieve total control over your fermentation temperatures. The only downside with these systems is that they're relatively expensive.

               
Note: In addition to perfectly controlling fermentation temperatures, the same glycol set-up can be used to cold stabilize wines! What's more, with the addition of a fan unit, you can use it as an air conditioner to maintain cellar temps throughout the year. How's that for getting the most out of your investment!

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