Tom, I think John probably had it right when he suggested your sorbate
might be old. Six to eight months after the jar is opened is about
max shelf life for potassium sorbate. Most people don't buy sorbate
in a jar, but rather buy a 1 or 2-ounce supply in a little ZipLoc bag.
The shop owner bought it in a jar and opened it to fill those little
bags. You have no idea when he did that because he didn't (and won't)
date the bag. It might be four months old when you bought it.

I buy my sorbate in jars. The smallest amount I can buy in a jar is
55 grams. I buy 4-6 jars at a time. I never open one unless I have
several carboys and several gallon jugs of wine to treat--the reason
should be obvious. I date the jar when I break the seal and I throw
it out 3/4 full six months later. If I don't do this, I won't be
stabilizing my wine. I've tried using more to make up for the
deterioration, but there is a level at which you can taste it and,
like Tom S., I don't care for the taste.

By the way, how old is your potassium metabisulfite? It too has a
shelf life--about a year. Campden is the same.

If you don't have a spare refrigerator for cold stabilizing your
wines, think about getting one. Tom S. is right on that account.

Finally, Lum, Roberta's article is a classic and ought to be published
at least here at least every six months. Please feel free to do it
whenever appropriate. That's one broken record I can suffer through
for the benefit of those just joining us.

I'm off for to California for the next 3 1/2 weeks. I'll tune in
again in mid-January. Hope you all have personally rewarding
holidays....

Jack Keller, The Winemaking Home Page
http://winemaking.jackkeller.net/