Several of my reds have pH's around 3.5 or so and TA's from 6.5 to
7.5g/l. They are 10 months old and have not yet been cold stabilized. Tastes are tart but OK with the exception of the amarone (TA 7.5) which is tart like a lemon. I'd like to reduce both TA and pH in all of these reds.
Should I just cold stabilize or reduce acids with KHCO3 for example and then cold stab?
Also, different sources suggest different ideal TA's for finished dry reds. Pambianchi on page 83 suggests 4.0-5.5g/l. Don Buchan's excellent FAQ site
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suggests 6.5g/l. I know taste is the ultimate authority but what should I be aiming for here?
How does one reduce both TA and pH simultaneously?
First off, those sound like pretty reasonable numbers for a red wine, but I'm confused. If you reduce the pH the wine will become even _more_ tart.
Your best bet is to do a bench trial on a small sample before touching the main lot. Put some in a small plastic soda bottle (not completely full), squeeze all the air out and cap it tightly. Put it into the freezer overnight and then let it sit in the refrigerator until it thaws. That'll precipitate the excess tartrates. Decant the wine from the sediment and taste it after it comes to room temperature.
Don't worry about the numbers; concentrate on what it _tastes_ like. If it's still too acidic, try adding a little carbonate, shaking to release the CO2 and repeating the above.
Forget the numbers. Make it _taste_ good.
Oddly enough, this is accomplished by _adding_ acid (tartaric) and removing the excess as bitartrate by chilling it out.
I don't proclaim to be an expert winemaker BUT I don't see any problems with what you got. I'd give it some time and let the bitterness fade away amd trust me, it will. If your in a hurry then cold stabilize but I think your ok . If you want, take 1 gallon and cold stabilize it and see what you think. IMO, taste is everything so go by that. You'll be surprised to see how accurate your taste instincts are.
I'm concerned about the pH being too high from a stability point of view. I'd like to age the wines if I can get the chemistry right. Pambianchi suggests pH closer to 3.1 or 3.2. Ideally I need to lower pH a little and TA even more (I think).
So, basic procedure(?): add tartaric to lower pH and then chill (with or without a reducing agent like KHCO3)?
As long as your pH is below 3.65 or so, you will drop both TA and pH when you cold stabilize. The trick is for you would be to add KHCO3 to lower (wtih cold stabilization) acidity, but not so muchtat you raise your pH above 3.65.
But what Tom said is exactly right--get it so that it TASTES right. Wine with a pH of 3.5 is absolutely stable. I'm happy with anything below 3.6 or so, and there are people who go much higher. Most reds will not have pH's anywhere near 3.1 or 3.2, and really, they don't need to.
Dave
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Red wine at pH 3.2 is pretty user-unfriendly. Sure, it'll be _stable_, but nobody will want to drink it!
As David said, pH 3.5 (and even higher) is perfectly acceptable for red wines. Actually, that's about where my Chardonnay usually ends up, and I've had no stability problems with it. The level of free SO2 is a bit higher, but 50 ppm free isn't all that high anyway.
I've had some very fine Cabernets in the range of pH 3.8.
FWIW, wine judges tend to prefer high pH wines over lower pH wines of equal quality.
Now Tom, let's not be all California-centric! Just 'cause you hot-climate folks have high pH's as a matter of course, it doesn't mean *everyone* does. There are lots and lots of lovely Rieslings (German, Austrian, New York!) whose pH's are in the pH 3.00 range.
:-)
Dave
**************************************************************************** Dave Breeden snipped-for-privacy@lightlink.com
This is not necessarily true. The TA is quite a bit more impactive on the organoleptic qualities of the wine than pH will ever be. If you can succeed in lowering both, the wine can become considerbly less tart.
As David pointed out, cold stabilization of this wine will lower both. If the pH is above 3.65, the pH will raise from tartrate precipitation. How much of a change is highly dependent on the specific concentrations of the various acids of the wine and is therefore unpredictable. With that said, I've had TA's drop as much as a gram per liter from tartrate precipitation. pH may drop by 0.15 a best. The level of pH when tartrates are forming is a factor for how much it will change. The further away from the wines pKa (typcially around 3.65) the more dramatic the change.
Making wine at high pH is a dicey proposition at best. This is the first thing Clark Smith will say when lecturing on the subject. (I just sat through another of his lectures a couple weeks ago). Even when conditions are proper, there can be premature browning of the wine. And where hybrids are concerned, it's no-man's land, as more than likely, there are not substantial tannin levels to have the wine keep for very long at all. Sulfites at these elevated pH's is virtually useless.
Red wines with TA in the 6.5 range should not be terribly tart. If they are, then I'd have to question the measurements accuracy.
This would help considerbly. Also, you don't mention whether or not the wines are ML pos. Depending on the malate content, this could take the pH above confortable levels for sulfite use.
I like my reds in the 5.0 to 6.5 range, but you've got the right idea that the taste is the ultimate tell tale.
Hi, Clyde - On another NG we had a similar discussion on the effect of cold stabilizing wines. IIRC, the pKa for potassium bitartrate mentioned was a lot lower than 3.65. It was more like 3.2 - and this data was from an organic chemist, who certainly should be a reliable source.
I wouldn't go so far as to say that, but it's true that it takes a good deal more free SO2 to maintain 0.8 ppm molecular SO2 at pH 3.8 than it does at
You know that I'm no chemist, but the way I understand this, the pKa of KHTa is not the issue here, but rather the pKa of tartaric acid in wine. Tartaric acid has a pKa of 3.5 in water, but because of the buffering effects of wine (created by the various acids and salts present) the pKa for tartaric in wine is slightly higher, usually around 3.65, depending on the grape variety, growing season, location, etc.
You differ from Clark Smith, who states that levels of 20 to 30 ppm is all that should be maintained in wines of higher pH, and that the purpose is only to bind acetaldehyde; not as a microbial disinfectant. I don't go there, so cannot say from experience; just hearsay!!
More for this discussion. Several years ago I cold stabilized a Vidal wine. There was a dramatic drop in pH. Ed Goist, who used to post valuable information here, sent me the response given below. Pretty neat stuff.
Bill Frazier Olathe, Kansas USA
From Ed Goist, February 2001 In wines with 11 to 13% alcohol cold stabilization will affect pH as follows;
start pH pH change due to cold stabilization 3.20 or less noticeable, substantial decrease in pH 3.21-3.40 slight decrease in pH 3.41-3.60 very minimal change in pH 3.61-3.75 slight increase in pH 3.76 or more noticeable, substantial increase in pH
This is because of the pKa for potassium bitartrate of 3.55 bitartrates are effectively an alkaline substance for a wine with an overall pH of 3.5 or lower, and they are effectively an acid substance for a wine with an overall pH of 3.6 or higher.
When tartrates are removed from wine with a very low pH, an alkaline constituent is effectively being removed and a greater proportion of acid constituents overall will be dissociated. This will cause the pH to decrease.
When tartrates are removed from a wine with a very high pH, an acidic constituent is effectively being removed and a smaller proportion of acid constituents overall will be dissociated. This will cause the pH to increase.
Hi Clyde - I'm not so sure we actually differ much on that topic. I wasn't necessarily _advocating_ maintaining 0.8 ppm molecular SO2 in a high pH wine; only pointing out that it's possible. However, I suspect that 80 ppm free SO2 might cause sulfite sensitive folks some problems as that high pH wine hits their stomach and the molecular free goes through the roof in that pH 3.0 environment!
For that matter, it seems to be fairly common practice to maintain molecular SO2 at 0.5 - 0.6 ppm in red wines.
I don't think I'd risk free SO2 as low as Clark Smith recommends for high pH wines though. I'd probably opt for an arbitrary maximum of ~50 ppm free and leave it at that.
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