How much do wine fermentation temperatures matter?

Topic suggested by Chris Rea

A LOT!
 
You may not know it, but the temperature at which your wine is fermented can have a profound impact on your results. Here are four ways that different fermentation temperatures can affect your wine:

1. Yeast Activity

Yeast is responsible for converting the sugar in your grape juice into alcohol. The rate at which yeast can do this is directly affected by temperature. Warmer temperatures will lead to more active yeast and a quicker fermentation, while cooler temperatures will have the opposite effect.

2. Aroma and Flavor

The temperature at which fermentation occurs can also impact your wine’s aroma and flavor. Warmer fermentations tend to produce wines with more fruity aromas and flavors, while cooler fermentations can result in wines that are more floral and mineral driven.

3. Mouthfeel

Another way that fermentation temperature can impact your wine is through mouthfeel. Wines that are fermented at cooler temperatures tend to have a lighter body, while those fermented at warmer temperatures can be fuller-bodied.

4. Alcohol Content

Finally, fermentation temperature can also affect your wine’s alcohol content. Wines fermented at warmer temperatures will have higher alcohol levels, while those fermented at cooler temperatures will have lower alcohol levels.  
 
SOLUTIONS

It is critical to monitor your temperatures throughout the fermentation process. Liquid crystal thermometers are inexpensive and easy to use. Floating thermometers are also a good choice. It is important to note your temperature ranges for reds and whites are different. Reds should ferment between 68-80 F. You can push the window higher or lower but be advised that lower temp’s risk stuck fermentation and higher ones can result in off flavors. For whites, the range is lower between 60-75 F. The low end is also risky for stuck fermentation so if you can maintain the mid-60s, you run less risk and will preserve more floral characteristics.

Sometimes controlling temperature is hard but there are some techniques you can use ranging from simple fixes to more involved endeavors. You can limit fermentation temperatures by placing the fermenter in a cool room, using a cooling jacket, or using a cooling device that goes inside the fermenter. You can also convert a refrigerator with a special thermostat that will give you a very controlled environment. Fermenting on the lower end of the temperature spectrum will give you a higher-quality wine with more complex flavors.

Conversely, if your space is cooler and you want reach higher temperatures, a brew belt is a simple and inexpensive tool to keep your batches warmer. You can also move your fermenter into a corner with a space heater. Even placing your fermenter inside another bucket will help as plastic is a natural insulator. This will give you a more fruit forward result with higher alcohol. 

So, there you have it! Now that you know, be sure to pay attention to the temperature the next time you are making a batch and think about what you like to drink. You can direct your fermentation process to suit your flavor preferences and a few degrees can make a world of difference. Good luck!