Cold stabilisation

Is acid removed? I thought the crystals were potassium tartrates - does their removal affect the relative acidity of the wine?

Tartrate crystals will form at any temperature. In the old days they were called "wine glass"

the colder you get it the faster it will form though. Although the crystals can partially redissolve if the temperature is raised this is fairly inconsequential, most of them will stay behind.

Potassium tartrate is formed wihen potassium ions react with tartaric acid and form a buffer salt. Removine that salt will raise your ph (if above 3.5 or so) or lower your pH (if below 3.5). Removal of tartrates (calcium tatrtate is also formed) will always reduce your TA, so this is a usefull method of making a wine taste LESS acidic.

Tartrate crystals will form at any temperature. In the old days they were called "wine glass"

the colder you get it the faster it will form though. Although the crystals can partially redissolve if the temperature is raised this is fairly inconsequential, most of them will stay behind.

Potassium tartrate is formed wihen potassium ions react with tartaric acid and form a buffer salt. Removine that salt will raise your ph (if above 3.5 or so) or lower your pH (if below 3.5). Removal of tartrates (calcium tatrtate is also formed) will always reduce your TA, so this is a usefull method of making a wine taste LESS acidic.

I've read that the ideal temperature is 28 F. In practice, anything under 40 F will do the job. Chill the wine and keep it there for at least a week, preferrably 2 or even longer Then rack the wine BEFORE it warms up, to keep the crystals from dissolving.

I rack before it warms usually but most of the acid that came out stays out even if the wine warms before racking. The crystals don't re-disolve in my experience. I rack cold too; but cold wine is more susceptible to oxidation so rack gently if you do it cold. Mine usaully drop at least a g/l. I use two racking canes, one in each carboy. I sulfite the fresh carboy first also. The wine fills gently from the bottom with no turbulence to speak of that way.

Joe

That slightly misrepresents the effect. Gases in general (and particularly oxygen in this case) are more soluble in cold wine than warm, but the reactivity (of oxygen) is actually lower in cold wine. The increased oxidation occurs when the wine returns to room temperature after having picked up extra oxygen while cold.

Tom S

Tom - this raises an interesting question I've never considered before; while potential for dissolved oxygen increases with lowered temperature, is it DO that is the issue when discussing oxidation of wine, or is it 'free' oxygen? Or both? The point being; if is is strictly DO, then your comment about oxidation increasing at higher temps would be counter-intuitive. But if free oxygen is the issue, then increased temp affecting oxidation would seem to make more sense.

Ok, I will give it a try. I would like to try to keep a watermelon wine that the recipe I used called for more acid blend than it should. I would like to try something that will take out acid before I try putting in something to neutralize it.

Thanks,

Roy

What makes you think they are not one and the same?

Tom S

At the risk of this becoming a sketch from Monty Python, I'll try again; dissolved oxygen and fee oxygen are avaulablee, chemically and biologically, in different ways (to verify, ask a fish). I was just curious if there was different effect on wine oxidation. Does anyone take DO readings of wine as an indicator of oxidation potential?

Somebody may, but I don't. I just make sure the free SO2 is where it needs to be prior to bottling.

Tom S