Winemaker Question: Cloudy White

Last week I had a white wine, served direct from the fridge at a fairly cold emperature, that was noticibly cloudy. When I went back to try it 2 hrs later, at room temperature (fairly warm), it was perfectly clear. No signs of cloudiness at all.
Any idea what was going on here??
Tom

I have never seen it in wine but there is something known as chill haze that happens to some homebrew beer. It sounds like the same thing. Cloudy when cold and clear once it warms up. No impact to the taste. Believe in beer it is related to some type of protein in the finished product.

Tom, Hi....

I've encountered this at times with wines that were not cold stabilized. When exposed to refrigerator-range temperature they take on a temporary cloudy-hazy appearance but once they return to a more acceptable temperature that vanishes. As stated above, not a reflection of a fault but do expect such wines to throw tartrate crystals if they continue age. The tartrate crystals are not harmful either - in fact some of the more perverse of my European friends actually enjoy chewing them.

Best
Rogov

Yes, as Rogov says, it sounds like tartaric coming out of solution. Harmless. If you want the wine cold and clear, chill the bottle upright in your fridge for long enough to let them settle on the bottom.

From other responses I've got, I suspect this was merely a protein haze, rather than tartrate/cold stabilization issue. Protein hazing
is most commonly addressed by a light bentonite fining.
Tom

Based on your description, it sounds like tartrate crystals.
From: The Home Winemakers Manual by Lum Eisenman

Bentonite
Bentonite is an extremely fine, clay-like material. It has a negative electrical charge, and it is used to remove positively charged particles from wine. Bentonite is most commonly used to remove excess protein from both white and blush wines. It is also used for clarification fining of white and blush wines, and sometimes bentonite is effective in clearing hazy fruit wines.

A bad protein haze is very unsightly in a bottle of white or blush wine. The protein particles are light and fluffy, and they produce a swirling cloud when the bottle is disturbed. When white or blush wines are subjected to warm storage conditions, protein hazes can form quickly, and all commercial white and blush wines are specifically treated to remove the excess protein before bottling. Winemakers call protein haze hot instability because warm storage conditions trigger the phenomena. A graphic demonstration of hot instability can be easily produced by leaving a bottle of Sauvignon Blanc in a car trunk on a hot summer day.

Tartrate Crystals
Potassium bitartrate has several interesting physical properties. (1) Only small quantities of this material can be dissolved in grape juice. (2) After grape juice ferments and alcohol accumulates, even less potassium bitartrate is soluble in the water-alcohol mixture. (3) The quantity of potassium bitartrate dissolved in wine is strongly dependent upon temperature, and cold wine cannot hold as much potassium bitartrate as warm wine.

In combination, these three properties produce an interesting winemaking problem. Generally, grape juice contains all the potassium bitartrate it can hold when the grapes are picked. Alcohol begins to accumulate when the grapes are fermented. As the alcohol concentration increases, the new wine becomes saturated, and potassium bitartrate precipitates out of the wine. As fermentation continues, more alcohol is produced, and more tartrate is forced to precipitate out of wine. By the end of fermentation, the new wine is over saturated with potassium bitartrate. The tartrate continues to drop out of the solution, but at normal cellar temperatures, tartrate precipitation is very slow. Often the tartrate crystals continue to precipitate for a year or more, so potassium bitartrate causes serious long term stability problems for the wine industry.

The following example illustrates a common tartrate stability problem. A new white wine is clarified and aged for several months. The wine is then filtered with a 0.45 micron membrane and bottled. The newly bottled wine is clear and bright, but the wine is still nearly saturated with potassium bitartrate. Ultimately, a consumer puts a bottle of this wine into a refrigerator for a few hours before it is served. The wine cools rapidly in the refrigerator, and potassium bitartrate precipitates out of the cold wine. (See property number three above).

As tartrate drops out of solution, suspicious looking crystals are formed in the bottle, or dense hazes form. Tartrate hazes are very unsightly, and sometimes the consumer mistakes the tartrate crystals in the bottle for glass particles. In any case, the consumer is unhappy, and the winemaker is embarrassed. All commercial white and blush wines are cold stabilized sometime during the winemaking process to remove the excess tartrate material before the wine is bottled.

Hi Tom,
I agree with Daniel, Peter, and Howie. As mentioned by Howie, usually to induce a protein haze the wine sample is heated then cooled uniformly. To make the sediment much more “firmer” (easier to rack clear) bentonite is used. After the wine got closer to room temperature did you notice sediment at the bottom of the bottle? If not, most likely as the wine warmed acid fell back into solution, (“warmer” wine can hold more acid in solution than “colder” wine).

Salute

Tom, Hi....

I've encountered this at times with wines that were not cold stabilized. When exposed to refrigerator-range temperature they take on a temporary cloudy-hazy appearance but once they return to a more acceptable temperature that vanishes. As stated above, not a reflection of a fault but do expect such wines to throw tartrate crystals if they continue age. The tartrate crystals are not harmful either - in fact some of the more perverse of my European friends actually enjoy chewing them.

Best
Rogov

Daniel, I have had a lot of wines do exactly what you are talking about. But I have had wines do what Tom is talking about too. When the latter happens and I let it settle out, it seems to be a fine powder that settles to the bottom of the bottle, and it is easily stirred again while being poured.It is ugly, but doesn't detract from the flavors, just the appearance.

Again this is from the beer world but seems to be the same thing.

From http://www.howtobrew.com/section1/chapter7-4.html

Rapid cooling also forms the Cold Break. This is composed of another group of proteins that need to be thermally shocked into precipitating out of the wort. Slow cooling will not affect them. Cold break, or rather the lack of it, is the cause of Chill Haze. When a beer is chilled for drinking, these proteins partially precipitate forming a haze. As the beer warms up, the proteins re-dissolve. Only by rapid chilling from near-boiling to room temperature will the Cold Break proteins permanently precipitate and not cause Chill Haze. Chill haze is usually regarded as a cosmetic problem. You cannot taste it. However, chill haze indicates that there is an appreciable level of cold-break-type protein in the beer, which has been linked to long-term stability problems. Hazy beer tends to become stale sooner than non-hazy beer. The following are a few preferred methods for cooling the wort.

And this from http://www.bacchus-barleycorn.com/PDFfiles/LearnMore/Chill%20haze%20prevention.pdf

Chill haze is a result of polyphenols (i.e. tannins extracted from malt and hops) combining with proteins to form particle which are insoluble when the beer is chilled and scatter light making the beer appear cloudy. When the beer is at room temperature these particles are soluble so the beer appears clear.