Acids in wine
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nicklepickles
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false. acids wont change, unless you do a malolactic fermentation, where the malic acid gets broken into lactic acid
There are a couple of yeast strains that are well known to reduce malic acid levels during fermentation. 71B (Norbonne) is one, and there are several others. One strain, I believe G-something, is said to reduce malic acid levels by 30%.
Twerp129
Well-Known Member
Acids definitely change during fermentation, but it depends on a variety of things. PH shifts can vary wildly from vintage to vintage even.
gratus fermentatio
Well-Known Member
Some acids WILL change, it just depends on the type of acid. Malic can be metabolized by some yeast strains & eventually it becomes alcohol. Malic can also be metabolized by bacteria as a malo-lactic fermentation (MLF). Ascorbic acid will age out over time. Under certain conditions, tartaric can actually precipitate out of solution as small crystals that fall to the bottom.
This might explain the various acids better than I can:
http://www.grapestomper.com/wineacids.html
Regards, GF.
This might explain the various acids better than I can:
http://www.grapestomper.com/wineacids.html
Regards, GF.
Jacob_Marley
Well-Known Member
Citric is metabolized during Malolactic Fermentation ... this is not by yeast but by lactic acid bacteria. The result is an increase in diacetyl (and on the way to it, acetic acid) ... particularly at higher pH. This however is not a suitable method to try to lower citric acid content in wine. Too much diacetyl is generally a fault in wine and while one could leave the wine on the lees to then try to reduce the diacetyl, all this is not a worthwhile pursuit. Further, the acetic acid produced is vinegar.
There is no particularly good way to reduce citric acid content in wine other than blending with a wine of less acidity ... or if it got there because you added it - then not adding so much to begin with ... or if in fruit wine production - then starting with juice that does not have so much of it.
You can not precipitate citric out with acidex or anything else. Citric is just too soluble.
With citric it *is* possible to modify the hydrogen ions by use of things like calcium carbonate and shift the pH upward a bit, and while pH does influence the acid taste in wine ... the shift is slow to do so with citric and by the time you had much effect the wine would have off-flavors. Not worth it.
Malic ... yes. As Yooper said.
There is no particularly good way to reduce citric acid content in wine other than blending with a wine of less acidity ... or if it got there because you added it - then not adding so much to begin with ... or if in fruit wine production - then starting with juice that does not have so much of it.
You can not precipitate citric out with acidex or anything else. Citric is just too soluble.
With citric it *is* possible to modify the hydrogen ions by use of things like calcium carbonate and shift the pH upward a bit, and while pH does influence the acid taste in wine ... the shift is slow to do so with citric and by the time you had much effect the wine would have off-flavors. Not worth it.
Malic ... yes. As Yooper said.
