Topic of the Week 5/17/2019 - Advanced

Odes to the old vines last post by  and . Great reference to the excellent article written by !

This week: Fermentation temperature 

What are the typical ranges for white wines? What about red? What purpose does each range serve?

  • This is a juicy topic! 

    I'm many ways S. cerevisiae are a lot like us in terms of temperature preference. That being said, different yeast strains vary in their optimal temperature range. I like to think of this again as people, some people can't stand cold (me) while others live for it (crazy people). 

    These days, winemakers have a great deal of control in regards to temperature which is one of the most influential aspects of fermentation.

    In general, cooler temperatures around 10-20 ºC bring about a fresh and fruity result as is preferred for many white wine styles. This range can also prolong a fermentation building complexity and increasing fruity esters and flavors. Too cold however and the fermentation may slow to a stop.

    In red wines, temperatures between 24 and 27 ºC are generally considered standard (Jackson). If a wine is fermenting on its skins, as in red wine production, a higher temperature can aid in extracting flavor from these skins. Another thing to consider is the vessel in which the must is fermenting. The larger the vessel, the higher potential temperature increase once fermentation commences. Get a ferment too high and yeast will become stressed producing reductive and off flavors.  

  • White wine range 50 - 68 F

    Reds wine range 77 - 86 F

    There is obviously some variation based on winemaker choices, but the hard lines are 50 and 113 F. Below 50 F and the yeast will work too slowly or not at all, and above 113 F yeasts die.

    The temperatures used for white wines tend to preserve varietal aromas, prevent oxidation and inhibit malolactic fermentation (if desired for more aromatic and lighter bodied whites.) 

    The range for reds helps facilitate extraction of color, flavor compounds and tannins from the skins while still retaining some fruit aromas. 

    However, it is important to note that temperature is just one small factor in fermentation, and all of its effects can be affected by vessel shape and composition, time of fermentation and any type of physical agitation, i.e... pigeage, remontage.

  • Good mention about yeast strains being different. Purely anecdotal, I’ve noticed that a lot of ambient yeast ferments never generate as much heat as commercial, pitched yeast, and can usually tell when one yeast dies off and another (likely commercial yeast that are ambient in the cellar) takes over. The temp and aromas both make a large switch at that point. 

  • I'm surprised no one has mentioned a less sexy aspect of fermentation temperature -- speed.

    The higher the temperature, the faster the fermentation. For many mass-market wines produced in large quantities, timing is extremely important. While I suppose we'd all like to think of wine as a hand-crafted product that the winemaker coddles and coaxes into the best product possible, the reality is that for many wines, the tanks need to be turned. Especially in compressed vintages where the fruit is coming in rapidly, even one extra day in tank can spell disaster for waiting fruit. For example, at Gallo's Livingston facility (largest winery in the world!), they aim for 5-6 day fermentations for most of their reds (the facility is where the bulk -- haha, no pun intended -- of their under $10 wines are produced; think Barefoot and Carlo Rossi). They use flash-detente to rapidly extract phenolics and tannins, then the must goes into tank with selected yeast strains that move quickly. Warmer fermentation temperatures are also a critical piece to getting the wines to ferment dry in this small window of time. To put that in perspective, barrel fermented whites kept in a cool cellar can take several months to go dry.