This seems to be a good place to bring up a related question: increased
acidity in stored bottles.

A 2001 Zin from Amador grapes started out with luscious fruit and good balance. No
acid was added during vinting. Maybe six months after bottling I finally got a pH meter
and measured it in the 3.5 range. 18 months after bottling, though, a sip of the
wine crashed into my stomach and the pH now measures 3.1. There is no sign
of acetification.

What happened? I don't see anything in the literature about pH dropping so
severely without acetic conversion.


Tom S wrote:
> "Bonaquisti" > wrote in message
> ...
>
>>Hi all,
>>
>>I made some wine from grapes last year (Zin) and fresh juice (San
>
> Giovese). We
>
>>tested them and both were low in acidity, so we added tartaric as per
>>instructions. The wine is clearing nicely, and at every racking, we
>
> tasted
>
>>some, it always tasted very good for such a young wine. I racked again
>>recently, and the wine now tastes very acidic to me, all of the carboys
>
> do!
>
>>My question: Is this a natural chain of events as the wine ages, and will
>
> it
>
>>eventually mellow? or is this how it is going to stay? If so, is there
>>anything that can be done to "soften" the acidity? Cold stabilization?
>
>
> Cold stabilization _might_ help, but I'll bet you over-adjusted the wine.
> You can reduce the acidity by adding potassium carbonate, but be careful you
> don't overshoot _again_! Try a measured adjustment on a small portion of
> the wine. Chill the wine deeply for a week or two to drop out the excess
> potassium bitartrate and taste it. If it seems about right, adjust all the
> wine proportionately and cold stabilize it before bottling. If the
> adjustment was a little too much or too little, you should have an idea of
> what would be right, so you can try that on a second sample.
>
> The right way to do acid additions is to measure the pH of the must/juice
> and add tartaric to bring it to a reasonable starting pH. Bear in mind that
> after ML the pH will be higher than where you set it, so you may want to
> compensate for that by targeting on the low side initially. For example, if
> the starting pH is 3.7, bring it down to 3.4 or so. Then after ML it will
> probably be about 3.5.
>
> Tom S
>
>


--
ernie San Francisco Bay AVA
California, USA
to reply, rack off the lees.