I would agree to some extent,
I have used this pre oxidation step under controlled conditions. It seems to
work well on fruit of sound quality.
Fruit that contains Bortrytis, however I don't believe should ever be
treated like this- laccase, an oxidative enzyme, can take hold and once it
develops can be difficult for the new comer to control.
May I also suggest that you take wine pH into account . In as much as
laccase does enjoy an acid environment at wine pH ( 2.8-3.7) In years where
Bortrytis may be a problem I recommend SO2 additions at the crush even
though laccase can be resistant to SO2 additions and sometimes two additions
are necessary. Laccase is imparted by Bortrytis and is a very strong
oxidant- attacks monophenols, orthodiphenols and even meta and para phenols,
diamines and ascorbic acid.
What does all this mean?- well in my experience, in good vintages where
fruit is sound ,try the pre- oxidation step, it does seem to lower the
susceptibility of further oxidation in wine.
The brown that drops out is merely quinones precipating out after binding
with SO2 (if added) though they will eventually drop out anyway.But this
binding between quinone and S02 does help stabilise the quinone against
further polymerisation. Oh oxidation is not actually prevented here but the
undesirable effects of it are.
Also many people don't realise that the rate of oxidation of wine is about
100 less than that in must anyway. So the comment that wine does not
further oxidise so readily is (not all the time but most) a furfy- some are
sure to disagree.
When fruit is poor consider using SO2 to help protect your juice from enzyme
oxidation and non enzyme oxidation as a scavenger of Hydrogen Peroxide
very oxidative compound). I do
I hope this is clearer to you
>I've been making Chardonnay for over a decade, and never use sulfite at
>crush. Any oxidation that occurs precipitates with the lees, and the
>finished wine is more stable than if the must had been sulfited. Also, the
>malolactic fermentation goes much more easily if no SO2 is present, so add
>SO2 only after ML is complete.