A question about "reduction"

Cellar Rats (ITB)
1

Anyone who drinks any amount of red burgundy knows that wine in barrel or in bottle can have some sort of sulpur smell that we can “reduction”. What form of sulphur is that and at what stage does it get into the wine?

Ive notice that the majority of the wine I make at home (from concentrate or fresh jucie) has varying amounts of sulfide smell from distressed yeast. Is this the source of the reduction sulphur chemicals? Something that comes from the stressed fermenting yeast? If not, what is the process and source?

Thanks for reading!

2

Here is an excellent exposition.

http://nanaimowinemakers.org/Steps/H2S_Issues.htm

P Hickner

3

More oxygen, at the right time, or more N, of the correct source, & timing (don’t go overboard with DAP).

Doing a YAN pre-ferment on grapes or must is helpful.

Have been mostly lucky myself, but I drive the sprayer, too. [wink.gif]

Link looks pretty good, except for one thing I noticed.

As far as I know, Mercaptans cannot be removed with copper treatment.

[cheers.gif]

4

Mercaptans can be removed with copper…Disulfides however cannot be removed with copper. Mercaptans can turn into Disulfides via oxidation…so that’s where the confusion may come from. As far as I know, the only thing to do with a wine with a disulfide problem is to get it into a reductive state (adding ascorbic acid is one way) and giving the wine enough time for the disufides to turn back to mercaptans…then you can remove the mercaptans with copper. Not getting disulfides in the first place in the better option :slight_smile:

Reductive compounds (thiols) can be formed either as a result of fermentation issues (h2s) or from the lees (or wine, but I think this is primarily a lees issue) in the barrel. It’s my impression that the current tendency of burgundies to have reduction issues is mainly from the lees…lots of reductive winemaking in burgundy (no, or less, racking of barrels means less oxygen in the wine) can lead to sticky lees…but sometimes there’s good things formed in those stinky lees (more often times bad things are formed tho).