At what temperature does tartaric acid precipitate out of wine?

Cellar Rats (ITB)
1

At what temperature does tartaric acid precipitate out of wine? I figure it must be somewhere above the wine’s freezing point, no?

2

Tartaric acid doesn’t. Potassium Bitartrate does. If you bite the crystals they don’t taste acidic.
As the temperature of a liquid decreases so does the solubility of things dissolved in it, so if the concentrations are high enough they begin to precipitate out. This can happen at room temperature, but it’s a very slow process. The colder you can get it, the quicker and more completely precipitation will occur.

3

ok … let me rephrase then: At what temperature does Potassium Bitartrate precipitate out of wine? I realize the answer might be a range, depending on various concentrations, but I’m basically trying to figure out the coldest temperature at which one can store wine (long term) without such precipitation happening. Let me know if my question needs further refining, and I’ll do my best to do so. [basic-smile.gif]

4

Typically around 55-60 degrees they are minimized, especially for short periods of time, but if you were to stick a wine that wasnt cold stabilized in the back of your refrigerator for a week, you will find some crystalline deposits on the bottom/side of the bottle. so the colder the temp and longer at the colder temp the greater chance of bitartrate fallout.

hope that helps
smig

5

Did you read all my post or just the first line?
Temperature only affects the rate of precipitation.
It happens more rapidly at lower temperatures
but can occur at any temperature over the long term.

6

OK boys. Let’s chill. No pun intended. neener
Brian, I’m sure you have seen red wine with tartrates in the bottom. As was stated above, it can happen at any temp. How cold were you wanting to store?

7

Unless those things are gases. Not relevant to the question, but…

8

ok … my post here was spurred by this post on the CT forum by another user:

Anyone have any authoritative insight into the potential to dramatically slow or even freeze a bottled wine’s development so aging can effectively be extended or put off far into the future? Seems that with proper isolation, reasonably low temparatures and other environmental factors (cork augmentation sealing?) it should be possible without adversely affecting the wine. Suspended animation of sorts for wine is the general idea.

my gut reaction to that post was to not store the wine at temperatures too cold b/c it would cause the precipitation of tartaric acid (now I know that said precipitation is of potassium bitartrate, not tartaric acid … although, I must say, someone I trust very much regarding matters such as this did once tell me that this precipitation was tartaric acid – I trust you guys that that individual was incorrect). Now I know that said precipitation will occur at any (or many) temperature(s). I believe the person who is the author of the CT post is hoping to literally “suspend” the aging process, or come as close to that as possible.

9

The equilibria as to “why” are escaping my memory at the moment, but red wines can really never be cold-stable. They are inherently tartrate-unstable. The colder you keep them, the faster it will go.

White wines can be stable to a point. Depends on the wine and the winery as to how cold-stable they will be, as some are aggressive in making them so while some are passive (and others don’t do it at all). Generally, 28-31 is the holding temperature, meaning that storing them in that range should be OK.

The freezing point of wine can vary, but is generally ~15-23 degrees F. If you are storing bottles in a cooler, of course, all these bets are off, as vibration and jostling from the compressor will aid in making the wines more unstable.

10

You can effectively stop aging by storing the wine in the 40F range. The wine ages so slowly that, relative to a person’s lifespan, it’s effectively suspended. Obviously, colder will be closer to true suspension, but you don’t need really cold temps to make an wine age so slowly that it’s hard to notice.

11

Hadn’t heard that before. I always understood that once your potassium drops below a certain level (1000?), then tartaric wouldn’t bind up with potassium and the wine was basically stable regardless of temp. Learn something new everyday- if you find a link, I’d love to read it.

12

It was something I remember Roger Boulton briefly touching on once…basically, polyhenolics and other “stuff” in red wine forms complexes with K+ and tartaric acid.

As the bitartrate forms, the equilibria for free K+ and tartaric changes, such that some of the complexes lose the K+ and HTA to freedom in solution, causing more precipitation and so on.

As I recall, polyphenolics also hinder nucleation of the crystals.

So, unless you want to remove your polyphenols to make a red cold stable (cutting off your nose to spite your face) it will be very difficult if next to impossible to get a red cold-stable in the traditional way in a reasonable amount of time.

At least that’s how I remember it.

13

I don’t know about all red wines, but I have worked with some that would have been considered “technically” stable. In 2005, when I was still in school, I worked at a bulk winery in the south valley. I was working at a winery, but technically was employed by an enzyme company that had developed an enzyme to aid in heat stability (and subsequently found that it also aided in cold stability). It was a protease that chewed up proteins into bite sized pieces and got them out of the way faster, but also this helped with cold stab. I think this would be more of a utility for large wineries that have to do overseas shipping, but we had many reds that were both heat and cold stable according to this wineries parameters.

14

Just noticed this thread. I have some low-sulfur Morgon (Marcel Lapierre) that they recommend be kept below 64F. If I were to leave it in the fridge (40F) for a few months over the summer , is that likely to damage it? The problem is that as it is now, the cellar will gets up to 70F during the summer. Thanks.

15

My God. Women who know chemistry are just so sexy divine chocolate…

pepsi

16

I just had a bottle of rather delicate several years old Sonoma Cab in the fridge for probably 6+ months and it was just fine. In fact, it seemed to be one of the favorite WOTN.

17

Thanks, L–ah, you live well [wink.gif] !

18

I emailed Lapierre about it, and they said that the “only” problem from fridge storage for a few months (at 40F) would be that the cold might precipitate a deposit of bitartrate. So I assume from that answer and from what you said, that if I get a precipitate it won’t change the taste. Is that right?

19

It depends on your starting pH. Now, in the aforementioned Cab I saw no tartrates. But generally, when you are cold stabilizing a wine, if your initial pH is about 3.65 or lower, you can actually see the pH drop as much as 0.2 due to the gain of an H+ atom for each molecule of KHT precipitated. If your starting pH is above 3.65 the opposite can happen. This happens due to the removal of one proton for each tartrate anion precipitated. But remember, as stated above, this takes a long time at refridgerator temps, generally. When we cold stabilize in the winery I generally set my take thermostat at 28F.



Yes Mark, I’m talking chemistry again. flirtysmile

20

I once tasted a bottle that had precipitated quite profusely – in my notes for that wine I noted a lack of acidity. When I later tasted another bottle of the same wine (that hadn’t precipitated) it had noticeably greater sense of acid. It was an ‘05 or ‘06 Paso Zin – a big wine, to say the least — I’d be surprised if the pH on that wine was less than 3.65.