Identify the End of Primary Fermentation

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Jan 24, 2010
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What is the ideal end point for primary fermentation? Is there a PA or SG that typically works well? I just started started a basic batch of concorde grape juice wine 3 days ago. (5 gal) I used premier cuvee yeast and fermented in my garage at 60 degrees in a 6.5 gal plastic fermenter with airlock. The initial PA reading was 15.25%. Three days later after some serious bubbling and foaming for the first two days, I'm measuring PA 5.75%. Is this possible? The bubbling has subsided significantly but there is still noticeable activity. When should I rack? A target PA would be helpful. Thanks!
60 degrees sounds really low, should be 70-75. From what Ive read, alot of people have trouble even getting the must to start fermenting below 65. And colder temps usally leads to slower fermentation... I normally rack to the secondary at a SG of 1.02
After fermenting a few days you aren't dealing with PA anymore because a percentage is already alcohol :p

What is your SG? on most kits you are looking to get under 1.000. So give your initial and your current SG :)
Concur with Atribune

SG will determine when the primary fermentation is complete. Typically, this occurs when a SG is at 1.000 or less. This is considered ferment to dry. Some kits will have you rack the wine when the SG is at 1.010. This is referred to as racking to the secondary....reality... its a continuation of primary fermentation until the must reaches 1.000 or below.

Below is some info on PA or what I think you mean is TA or Total Acidity:


In the U.S., the total acidity (TA) of a wine is measured assuming all the acid is tartaric. This allows one to determine a value for total acidity that is consistent. A high TA is 1.0%. Most people would find this level of acidity too tart and too sour for consumption. A low TA, say 0.4%, results in flat tasting wine that is more susceptible to infection and spoilage by microorganisms. Most red table wines are about 0.6% total acid. White wines are usually a little higher.


pH is a measure of a solutions acidity and is analogous to the Richter scale used to measure the intensity of earthquakes, since both scales are logarithmic. For example, wine with a pH of 3 is 10 times more acidic than a wine with a pH of 4. The thing to remember about pH is that the higher the pH, the lower the acidity, and the lower the pH, the higher the acidity. So a wine with a pH of 4.0 is LESS acidic that one with a pH of 3.6. Although total acid and pH are related, they represent different ways of measuring acidity of wine.


hope this helps
By transferring to a secondary fermenter at SG 1.015-10.10 you're attempting to continue the fermentation process under an air lock until fermentation is complete. By doing this you will insure a CO2 blanket that insulates the wine from harmful oxygen.
There is no fixed point at when you should transfer from primary to secondary. It depends on the ingredients and on the opinion of the winemaker.

If the fruit is full of tannin you should transfer way much earlier as when there is no tannin in it.

If the colour is dark enough, and there is enough tannin extracted (see above) then you rack.

In many somewhat older winebooks it is recommended that the wine is transferred when the cap breaks down.

There is even a method called extended maceration in which the pulp is left in the wine for weeks when fermentation has stopped.

Use your own judgement and let it not depend on a meaningless figure like 1.020 or something like that.
Take a small sample, look at colour, taste for tannin and go from that.


Use the SG scale not the PA Scale.

The initial PA reading was 15.25%. Three days later after some serious bubbling and foaming for the first two days, I'm measuring PA 5.75%.

If he's using the PA scale on the hydrometer then that converts to approx 1.15 or so on the SG scale. If his second reading was 5.75 on the PA scale that would be around 1.044 or so on the SG scale.


I'd say he's just looking at the PA scale instead of SG.

All in all sounds like it's dropping appropriately.
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I really appreciate all the useful information. Yesterday I measured the PA again and it was at 1.0%. (SG 1.013 - I'll begin using SG in the future.) I read that Premier Cuvee yeast ferments very fast and can ferment in temps as low as 45. I'm just surprised that at 60 degrees it dropped from 15.25% PA to 1.0% PA in 6 days. Nobody seems alarmed at this so I'll go ahead and rack it.

By the way, I tasted it and the flavor was somewhere between sour baby diaper and dog vomit. Please tell me this is normal too.
I don't know about those flavors as I have licked neither, but I have tasted all of my batches at every point and straight from the fermentation bucket they can be horrible. I was really worried about my Black Cherry Shiraz because it was nasty, but the finished product was great! The wine will go through a bunch of different taste as time goes on. Clean sanitize and rack it!
Oops, I just plainly missed the word: grape juice...........

Thought you were fermenting on the skins...........


Thanks Luc,
The batch I was asking about is nothing fancy... just 70% concorde grape juice, 30% real black cherry juice. I do have a batch of blueberry wine going which is made from real fruit. I'm using montrachet yeast and fermenting at 70 degrees. Your advice should be very helpful. Thanks again.

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