I was in piedmont visiting elio grasso and they said that prior to bottling, the wine goes through cold stabilization at close to 0C. In general, it sounds like this raises the pH of the wine, but does anyone know of other impacts on the wine? I imagine this technique wasn’t used until more recently so does this generally affect the ability of the wine to age well? I didn’t ask specifically, but it didn’t look like others in the region were using this technique.
As strange as it sounds, the pH either goes up or goes down as a result of cold stabilization. If the pH of the wine is below 3.65 then the pH drops as the wine is cold stabilized. Otoh, if the pH of the wine is above 3.65, the pH goes up as it’s cold stabilized. The reasons for this involve the chemistry of acids, and probably aren’t interesting enough to bore you with 
The other impact of cold stabilization that I’ve heard about is that it reduces the amount of colloids in solution (colloids are tiny tiny solids that stay in suspension indefinitely in the wine). I’ve heard that the colloids can be reduces by as much as 40%. Colloids generally improve the texture of a wine, so cold stabilizing has the possibility of making the wine texture harder and/or more astringent.
Otoh, cold stabilizing lowers the TA (titratable acidity, generally associated with the tartness of a wine)…maybe the colloid reduction is minimal and the benefit of lowering the TA (i.e. less acid structure in the wine) is a win for them (possibly without losing any aging ability?).
It’d be interesting to hear more about why they’re doing this, if anyone knows.
Thanks Eric - not sure if it’s the main or only reason but they cited one of the purposes was for clarity. They wanted to precipitate out as much as possible. If anyone else has talked to them about it I’d be curious to know more too.
Interesting; I’ve never heard of cold stabilization with red wines.
Eric, I know you’re more educated in these matters than I am, but are you sure cold stabilization reduces colloid content significantly? I don’t remember reading that anywhere. Can you refer me to a source of that information? If you don’t know of one offhand, I’ll pull out a couple of books and start reading.
I wonder if this producer has had issues with tartrates in the past. The main reason white wines are cold stabilized has to do with appearance more than anything else. If not for the fact that wine gets ‘mishandled’ at times and put though tough temperature conditions, most white would not be cold stabilized.
The general consumer seems to get freaked when they find tartrates either floating in suspension or sitting at the bottom of a bottle of white wine. These won’t ‘hurt’ you - they just don’t look very nice.
Curious . . .
Cheers!
Anyone else remember the full page tartrate explainer ads German importer Deinhard used to put in mainstream magazines about “Wine Diamonds, your seal of quality!”?
Eugene,
Are you sure he’s cold stabilizing everything? He might have been talking about the Chardonnay, or the Dolcetto…It’s a very common technique to avoid precipitation in bottle, but usually used for whites and maybe reds bottled young.
The Italian market doesn’t like tartrates, I tell producers that we have more broadminded consumers over here.
It’s a relatively recent paper that I read…I’ll look around to find the article again (my computer crashed before I got a chance to bookmark the page unfortunately).
I tell that story when talking about the technique. It is more or less a sign of quality, or at least a less manipulated wine…
Any wine I decant that throws tartrate sediment immediately draws my attention in a positive way. Unfortunately, the less expensive the wine, the more manipulation usually takes place. It’s rare to run into sediment in daily drinkers and other QPR-like wines.
We recently had a vintage of Sagrantino based Rosato that, when it hit about 45°F, suddenly went cloudy. The tartrates were so small they stayed in suspension and just made the wine look like translucent pink coral. FREAKED some people out but now most people wonder why the new vintage doesn’t do that.
This is interesting! 3.65 is a sort of magic number for the pH. Doesn’t this also imply that as potassium bitartrate precipitates over extended periods of time, the pH will behave in the same way? From the standpoint of aging, the efficacy of SO2 is tied (I believe, but could be wrong) to pH and not TA.
A wine with pH below 3.65 then would lower its pH, lower its TA, and maintain effective antioxidant and antimicrobial buffer even if SO2 drops over extended aging. That sounds like a nice mechanism for softening a wine while maintaining structure and longevity. On the other hand, a wine with pH above 3.65 would become more flabby–both in terms of TA and pH–while losing protection against oxidation and microbes as it ages. This seems like an inherently riskier aging trajectory, though it shouldn’t be the only factor in aging capacity.
Here’s an explanation of what Eric said, plus a revision of the tipping point to 3.9 pH.
http://www.moundtop.com/pdf/Winemaking-TartrateInstability-rev2.pdf
What I was thinking when I saw this post was simply that because Nebbiolo has less malic acid than most other grapes, which is why ML has less effect, they are trying to compensate by reducing the higher tartaric to raise the pH. But, that’s apparently not the whole story.
Thanks for the link Wes, didn’t (obviously) realize the tipping point is 3.9pH…great to hear, and always nice to have a bit more leeway to work with.
Unfortunately, I haven’t yet found the article that talked about cold stabilization reducing colloids.
Why would any producer want to raise the pH of a wine? I suppose in certain situations I can see lowering the TA, but why raise the pH?
I still rather doubt they’re doing this with Barolo, in any case.
Thanks for the info guys.
@Oliver - I was trying not to dig too much since I was there with another couple, but it sounded to me like they were doing it with all their wines. Is there a reason to do it with a Dolcetto or a Barbera and not a Nebbiolo based wine? I was also of the mind that this was only done w/ whites for clarity, but if you’re doing it to other reds, sounds like you could apply the same to barolo.
Eugene,
As I understand it, not being a winemaker myself, the classic elevage (two years in barrel) of a ‘big wine’ like Barolo goes some way towards naturally stabilizing the wines, and I’ve never heard of a wine like Barolo being cold-stabilized. Gianluca does produce several wines that would be more normal candidates for the technique, such as the Chardonnay, Dolcetto, and Langhe Nebbiolo.