Have an '07 Viognier that (for the second time) is clouding when refrigerating.
I put a one gallon carboy as a test batch into a 35 F refrigerator for
5 days. it s cloudy. The wine is otherwise (not refrigerated, kept at around 59 in the wine cellar) brilliant clear.
No pectic enzyme was used in vinification. Mlf was inhibited with lysozyme. Small bentonite fining some months ago. Free SO2 usually kept around 30 ppm. Wine is otherwise apparently clear, stable, and ready to bottle - but can't do so if it's going to cloud up when refrigerated!
Most references cite protein hazing when wines are raised in temp. Can this happen when a wine is refrigerated? What can i do about it?
I don't see in your message any indication that you cold stabilized your Viogner. Wines that have not been cold stabilized will precipitate tartrate crystals when refrigerated; hence the cloudiness. This cold instability cloudiness is a cosmetic defect; it doesn't affect the taste of the wine.
Cold stabilizing a wine requires chilling it to below 'refrigerator temperature' for an extended time. 27-28 F is ideal, taking 1-2 weeks. Higher temperatures require longer times, perhaps a month or more. This will drop out tartrate crystals, which settle on the walls and bottom of the container. Then test the cold stability of a sample of the wine by putting the sample in a refrigerator for two days or more, warm the sample back to room temperature and look for cloudiness and/or crystalline deposits. If you get those, the wine is not yet cold stable, and you may have to seed the wine by mixing in cream of tartar (about 1-2 gram per gallon) and repeat the cold stabilization process. Once the wine tests OK for cold stability, you rack the wine, leaving the tartrate crystals behind.
Some people combine bentonite fining and cold stabilization steps, adding the bentonite just before chilling the wine. This saves one racking step.
Please note that cold stabilization should be done after any blending (blending two cold stabilized wines can re-introduce cold instability).
Bentonite fining improves heat stability; it doesn't affect cold stability.
I am talking about a cloudiness that has occurred when the wine is placed into cold stabilization. The cloudiness is relatively heavy, and not clearing as the wine precipitates. The wine has been in the low
30's for one week - the cloudiness occurs at temps as high as the mid
30's.
I'm not sure about that in this case, there is no guarantee it's heat stable either. This could be a pectin problem though, why not warm it and add some PE to a small sample?
If that didn't do it would refine with more bentonite, you said it was a light fining. Chill haze can be caused by excess protein, anything that gets rid of excess protein would help if that is the issue. It's easy to test, that is why fining trials are recommended. If it's not cold stable it's probably not heat stable either.
Good points Joe. I will put some PE through a sample, at 'normal' temps, then test both heat and cold stability.
If it was only a cold precipitate issue (potassium tartrate or similar) then it should have been starting to clear and precipitate, or so it seems to me. But the haze is a suspended heavy cloud - giving me cause to think it's a protein hazing. Thanks again.
DrinksForum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.