Does fermentation naturally raise must temperature?

[Ron0126]

Currently have a Fontana Chardonnay kit in primary with French oak chips in my underground basement. Yeast is EC-1118, pH is 3.2, ambient temp is 68 but must temp has risen steadily and now stands at 80. I haven't measured TA.

5/24 -- temp = 74
5/25 -- temp = 72
5/26 -- temp = 78
5/27 -- temp = 80

Is this normal? Fermentation is going strong (which I'd expect at 80) but the basement about 10 degrees cooler than the must. Will a fermentation naturally raise temps?

All three other carboys (white grape concentrate, strawberry, and apple) are in secondary and perfectly match the ambient air temperature.

 

[sour_grapes]

Is this normal? ... Will a fermentation naturally raise temps?

Yes! Fermentation is an exothermic process. The yeasty beasties are busily liberating the chemical energy stored in your sugar. Although they use some of this energy to create other biomolecules, much of the energy is "wasted" and heats up the must. Just like when you and 100 of your friends stand in a crowded room, the room gets hot!

 

[Ron0126]

Yes! Fermentation is an exothermic process. The yeasty beasties are busily liberating the chemical energy stored in your sugar. Although they use some of this energy to create other biomolecules, much of the energy is "wasted" and heats up the must. Just like when you and 100 of your friends stand in a crowded room, the room gets hot!

Ok, whew! Thanks! I was beginning to wonder if I'd inadvertently done something wrong.

I appreciate your quick response!

 

[Scooter68]

If the temps start edging over 100 you might want to consider evacuating the premises. :<



Just kidding - That's one of the things about the process. If the fermentation raises temps above the limit of the yeast, the process will kill itself off. So the real concern would be to know the limits of the yeast and keep it in it's "happy zone." From the numbers you give your yeast beasts are VERY happy

 

[balatonwine]

80°F is okay for red wines, but is a bit high for a white wine like Chardonnay in primary. More likely to loose volatile aroma compounds, which are more important with white wines. During ML then 80°F is okay, but at the upper limit for a white. If this is the primary, I would try to cool it down if possible.

 

[JohnT]

The optimal fermentation temperature depends on exactly what you are trying to achieve.

A "hot" fermentation tends to "burn*" a lot of the fruit flavors off. Slow/low fermentations are regularly preferred for wines like a Riesling, where the winemaker desires a "fruity" aspect in the wine's flavor.

*burn - for lack of a long explanation, let's just say "burn".

A white wine like chardonnay, however, is routinely fermented "hot". Chardonnay is an odd duck in the white wine world. It is more complex, has a more tannins, and is regularly barrel aged (unlike a fruity whites).

I normally track the temperature during fermentation. There is a distinct "curve" in the temp with a "peak" during the height of fermentation.

A Riesling, I will try to keep in the mid 60's to 70 degrees. Fermentation can take as long as 3 weeks.

For a chardonnay I like a peak of 85 or slightly above. For my reds, I like a peak of 89 to 90 degrees. In these cases, fermentation usually takes 6 days with a peak happening on day 3 or 4.