Today’s letter is “F”, so we’ll talk about Fermentation: the magical transformation of the sugar contained in grape and fruit juice into alcohol and carbon dioxide (CO2) by yeasts. Fermentation is generally conducted in tanks or barrels at the winery, and for the home winemaker, 8-gallon buckets.
There’s a trick to fermenting red vs. white wines, especially when you remember that heat is a catalyst. By definition, when it is applied to a chemical reaction or biological process, it speeds things up. The same is true for fermentation. Makes sense, right?
The higher your fermentation temperature is, the faster your yeast will convert sugars into alcohol and carbon dioxide. While this sounds great on the surface, you never really want to rush anything when it comes to making wine. Fast is not better.
Warm fermentation can lack character and change the overall taste of your wine. Cooler fermentation temperatures help preserve the uniqueness of your specific fruit, and helps the character and flavor shine through.
For better or worse, cool fermentation takes longer to complete. This is the beginning of that ‘patience’ you need when making your own wine.
Red wines are recommended to be fermented between 70 and 80 degrees Fahrenheit (20-30 degrees Celsius). You’ll get better color and tannin extraction at the higher end of this spectrum, which is good.
But the caveat is that in this temperature range, fruity flavors and aromas don’t get preserved. That’s good for some red wines, though, especially if you’re going for a dry red.
Because fruity flavors aren’t preserved well at the higher temperature for a red wine, I generally keep it between 60 and 70 degrees Fahrenheit, since I want the fruity flavors to be prominent, especially when I’m making a Blackberry or Cherry version. Remember, I like to make tad bit sweeter and fruitier reds vs. the ultra dry reds.
When you’re making a white wine, the fermentation temperatures should be between 45 and 60 degrees Fahrenheit (7-16 degrees Celsius). The lower temperatures help preserve fruitiness and volatile aromatics, characteristics more in line with a white wine.
Of course for either, when fermenting at a lower temperature, it’s going to take longer. Just stir the must daily and let it do its thing, monitor the temperature and be patient! If you’re fermenting cold (like 45 to 50 degrees F), it could take a couple of months to complete the fermentation.
Here’s where the ‘balance’ comes into play – going beyond ideal fermentation temperatures can cause problems. If you ferment too hot or too cold, your wine will suffer.
Fermentation that gets too hot not only ferments too fast, but it could lead to “cooked” flavors. Your wine will taste like it was boiled on the stove. No one wants that! Plus, yeast can only tolerate certain fermentation temperatures – if you go beyond their maximum temperature tolerance, they’ll die off, which means your wine won’t actually ferment.
Keep in mind that heat is produced as the yeast is doing its work. Even if your wine is stored where the room temperature is within the ideal temperature range, your wine could still over get over heated – which is why you want to keep an eye on the temperature throughout the fermentation process.
At the other extreme, if your wine gets too cold, your yeast will go dormant. This is what is called a ‘stuck fermentation’. The good news here is that when your fermentation temperature rises again, the yeast will likely wake up again and continue fermenting.
And if it doesn’t ‘wake up’, you can pitch more yeast and restart your fermentation, and you don’t have to worry that your wine will be damaged by excessively cold temperatures compared to the damage that can be done with too much heat.
I recently bought a heat belt that’s designed specifically for the fermentation bucket – it’s been chilly in the basement as we wait for winter to fully depart and spring to warm up, so I’m actually taking advantage of the cooler temperatures and fermenting white wine, but if I decide to go ahead to start a batch of red wine, I’m covered with some controlled heat for the fermentation.
You can use a kitchen thermometer to monitor the temperature, or they do make a self-adhesive temperature strip that sticks right to the side of your carboy or fermenting bucket to keep tabs on the temperature. Easy peasy!
Monitoring temperature and maintaining ideal temperature ranges is a very important part of making a great wine. Excesses above or below the ideal range will have a direct impact on your finished wine, including whether or not it finishes at all.
Keeping your wine in the house is often the best option for the amateur wine maker, as we tend to keep our homes within the ideal temperature ranges listed above. Small adjustments may be necessary, but luckily the methods for making those small adjustments are doable.
Winemaking is so much fun – at least for me – and am tickled every time I give the wine as gifts to friends and family who love drinking it as much as I love making it. While we go through this alphabetical series on winemaking, if you have any burning questions, be sure to ask them in the comments below, and I’ll reply there – and maybe even highlight your specific question(s) in a future post!
Thanks for joining me in this fun adventure!