Help understanding "buttery taste"

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Khristyjeff

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The 2nd wine I ever made was an Australian Cab Sauvignon from RJS. It was their high end En Primueur series. For the longest time, even after a year, I thought it had kit taste (of course how would I know since this was only my second wine?). Then over winter it did get a few wine diamonds in the carboy with temps in the mid to upper 50's. Then I described it as tasting buttery--is that malic acid? I'm used to cab sauv's having a little more bite to them--this buttery version was very off-putting.

Now after 2.25 years, it tastes good with just a hint of butter. Still not quite what I'm used to but enjoyable none the less. So, what is this that I've experienced? Is it something you've had happen before? Is there anything I could have done differently for future reference? Or is this simply, "wine tastes weird, let it age until it tastes good" situation?

Thanks for your thoughts.
 

sour_grapes

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Well, clasically, the buttery taste in wine comes not from malic acid, but from the metabolites produced by MLB during MLF. When MLB chew on malic acid, they produce lactic acid, which is creamier and less harsh than malic. When MLB chew on citric acid, they produce diacetyl, which is literally what they (formerly?) used to flavor popcorn with artificial butter flavor.

Of course, one does not typically perform MLF on kit wine...
 

Khristyjeff

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Well, clasically, the buttery taste in wine comes not from malic acid, but from the metabolites produced by MLB during MLF. When MLB chew on malic acid, they produce lactic acid, which is creamier and less harsh than malic. When MLB chew on citric acid, they produce diacetyl, which is literally what they (formerly?) used to flavor popcorn with artificial butter flavor.

Of course, one does not typically perform MLF on kit wine...
Thanks for responding.
Yes. Lactic acid makes much more sense. So under this scenario, MLF happened naturally. lactic acid was produced causing the buttery taste. Then, apparently, aging neutralizes the lactic acid and the wine becomes tasty. Does that sound about right?
 

CDrew

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Thanks for responding.
Yes. Lactic acid makes much more sense. So under this scenario, MLF happened naturally. lactic acid was produced causing the buttery taste. Then, apparently, aging neutralizes the lactic acid and the wine becomes tasty. Does that sound about right?

No, the lactic acid remains lactic acid. There is very little citric acid in wine from grapes, so diacetyl isn't really an issue. But if you are making a kit wine, citric acid or acid blend may have been used to correct the pH, which would supply the substrate for dacetyl production.

Here is a quote from UC Davis:
Malolactic bacteria also have to capacity to metabolize citric acid. Citric acid is only present in small amounts in grapes, unless added. The metabolism of citric acid is not seen in commercial winemaking, but its metabolism can have an important effect on the formation of diacetyl.

The full citation with more than you want to know is here: LINK
 
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