Primary fermentation temperature

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Oct 26, 2007
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Hello to all,

I've been making red wine from fresh crushed grapes for few years and I am now in the process of enhancing my wines taste. I have a question about the primary fermentation temperature of the must.

After crushing the grapes about (850 pound), I leave it all in the vessel for about 6 to 7 days to extract the flavour and colour, before pressing it out and letting it finish fermenting in bulk. Recently, I read that the primary fermentation should be done in a very controlled temperature and not approach or exceed 90F .

Over the last three years I noticed that the fermentation would start at a SG of 1.095 to rapidly reduce to 0.995 in 6 to 7 days (sometimes before pressing the must). After 3-4 days of this rapid fermentation, the temperature of the must would rise to a stunning 90F for a day or two and descend rapidly to about 75F after 6-7 days. For sure the wine keeps fermenting for about 2-3 weeks at a very slow rate and temperature nearing the room temperature (about 72F).

Here is my question; could that rapid primary fermentation over a short period of time be somewhat bad for the wine and affect its taste? The room temperature where it’s fermenting is always kept in the 72-74F range.

Also it is important to mention that I do not use Metabisulfite in the must to later add cultured yeast. I let all the wild yeast do the work. I have never lost a batch of wine (maybe once few gallons out of about 50gal).

Thanks for any input on that.
If your wine is fermenting out in 6 to 7 days that should be fine to extract enough color. I like 7 to 9 days but you can't always control it. The problem with excessive must temperature above 90 degrees is that you can get a stuck fermentation. This means the yeast dies off and your wine stops fermenting. From what I am told, this is how pink zinfandel was created through a stuck fermentation. If you generally have problems with the must temp getting up around 90 degrees, try using a yeast that is more tolerant of higher temps.

As for not using potassium metabisulfite, can I ask why you don't you use it? There are some wine makers that simply prefer to let the wild yeast do its job but the problem is that with wild yeast you can get some undesireable effects. Sometimes the wild yeast is not strong enough to ferment the wine to dryness which can result in a stuck fermentation. Now maybe this isn't a problem if the fermentation stops at a level where the sweetness is desirable but again, that is something beyond control.

I find it best to dose the grapes with some meta (1/8 tsp per 36 lb box) or make a 10% solution of 50 ppm and add it to the must before adding yeast. I should say that you can skip the meta, and add yeast but then the wild yeast and the added yeast compete against each other. If the wild yeast strain is strong it can overwhelm the added yeast.
Thanks for your input Wine Maker!

That would explain why I get second fermentation later in the summer (probably MLF). I got myself a MLF Chromatography test kit this year to measure the acids and residual sugar levels.

As for not using Meta, it's just a personnal decision, as I like to keep the wine as free as possible from "chemical". I know it souds silly and adventurous, but it's a challenge. We are in 2007 now and wine making technique have evolved, but I still like the very old fashion way... and it's much more rewarding when you succeed!

I'll probably take a small batch this or next year and try adding some meta and yeast to compare the taste as an experiment.

Gotta go press that must now - my son is getting impatient! Thanks again!
Weird... I quick replied to Wine Makers' reply and it's not showing!?!? Anyway... like I said in my quick reply;

Thanks for your reply Wine Maker. You input is appreciated.

That is probably why I get a second fermentation in the following summer (probably MLF). This year I purchased a SO2 and MLF Chromatography test kit to measure the SO2 and acids levels to better monitor my wine behaving and anticipate any second fermentation.

As for not using Meta, it's just a question of personnal "taste". I prefer to avoid using "chemical" as much as possible in my wine to keep as natural as possible. I agree with many home wine maker that we are in 2007 and wine making technique had evolved. But I still like making it the old fashion way... and it's much more rewarding when it's a success!!

I just pressed my must today and already measured a SG of 1.000 at 77F only 7 days after crushing the grapes. About the same pattern as previous years. Also this year, for the first time, I destemmed the grapes by hand - quite a challenge. It took me 10 hours. Better be a good wine...!

Thanks again.
I prefer to use the word additive instead of chemicals. In wine making there are several things we do to ensure a proper fermentation, which can include adding yeast, nutirents, cultures, etc. Adding sulfite to wine acts as a preservative to protect against oxidation and bacteria that could otherwise spoil the wine. That being said, I do know wine makers that prefer not to add any sulfite to their wine. Too me, it's a big risk for the investment, not just money but time and effort.

The second fermentation is MLF and can start on its own after the primary fermentation if the wine is at the correct temperature, usually 73-77 degrees. I prefer to start MLF by adding a culture so that I can control when the MLF occurs. If you don't want MLF to occur you can do one of two things: 1) cold stabilize the wine, or 2) add an enzyme called Lysozyme. Lysozyme will prevent MLF or delay it if you want the wine to go through MLF later. The advantage of using the enzyme to prevent MLF is that you can feel comfortable the MLF won't happen after you bottle the wine (which would be a bad thing). Let's say that after primary fermentation you aged your wine in a cool place, let it clear and then bottled it. After it's bottled you move the wine to a warmer place, MLF can occur.

Destemming the grapes is a good practice, the stems can impart to much tannin and bitterness. But as you mentioned, it can be a time consuming effort if done by hand (another reason why you would want to protect the wine with potassium metabisulfite). I have a crusher/destemmer which does it automatically, lucky for me because when I make red wine I crush somewhere around a half ton of grapes.

In your original post you said you "I do not add meta to later add a cultured yeast", does this mean you do add a culture to start MLF?

Sounds like you have the process under control.
I agree with you that meta should be used to “stabilize” the wine for preservation. Not using it is VERY risky. In my case, most of my wine is gone in a year or two to the exception of few bottle that I would let age for fun. But none survived more than 4 years – didn’t put enough aside and had to open to “see” its taste.

But when I work with must and wine, I do wash thoroughly every piece of equipment that comes in contact with wine with a solution of metabisulfite and rinse with water so no meta solution touches the wine.

Following this years wine production (destemmed) I'll probably invest in a crusher/destemmer since I do too process large amount of grapes (and will certainly not destem manually again!)

As for my original post about “…to later add cultured yeast”, I was referring to the step I do not do (crushing, adding meta, yeast and let ferment). I do not add any culture to induce primary, secondary and ML fermentation. MLF starts on its own and it did enhance my last years’ Pinot Noir taste...!

Also I do not bottle my wine. I let it age in bulk in demijohns or oak barrel and transfer it in smaller container as I drink it. That way I reduce oxidation and ensure the taste is uniform in a batch, but could may vary from one vessel to another. I find it also allows MLF to take place “easier” and distribute uniformly the results.

This is the pleasure of making and aging wine; discovering taste and flavour, guided by Mother Nature and… little experimentation!

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