I have had some good advice from this wine group but still remain
confused about when to use sulphite.I have successfully made some
excellent red and white wine from grapes grown in southern England.I
seem to get some very good juice (Brix 19)with a good acid balance.My
good wines were my first attempts a couple of years ago,but I recall
that they were drunk within about 12 months after harvest.My recent
problems have been with longer storage wine which unfortunately has
been without any sulphite.The whites have become somewhat flat and
with a touch of sherry like flavour,and the reds have lost their
fruitiness and also become a little metallic.I am sure that this is
all due to oxidation,and I certainly plan to use a minimal amount of
sulphite for this years winemaking.I thought that I would be making
organic wine,but I have discovered that organic winemakers do use
sulphites or the complete purists do every operation under a CO2
blanket.I certainly do not wish to go down the CO2 route,so I am
resigned to using a minimum amount of sulphites,but I am unclear when
to use the sulphites.

I usually wash and sort my grapes and have been letting them ferment
on the natural yeasts.All of the grapes I have processed so far have
fermented the natural(+added) sugar out completely in a few weeks.As I
understand it,the early addition of sulphite (e.g.50ppm)is used to
kill off any remaining bacteria and suppress the 'bad' yeasts.My
question is whether this sulphite also absorbs oxygen at this early
fermentation stage,and therefore keep the juice fresh?I thought that
the CO2 given off during the fermentation protects the wine from
oxidation,but maybe the oxygen remains to do damage later on.So is
this early sulphite addition important?

The next question is whether to add sulphite at the first racking
stage,say after a couple of months,when the wine is fairly fully
fermented(another 50ppm?).I understand that most of the initial
sulphite (if added) will be used up during the fermentation process,so
maybe this is the most important addition.I probably do not expect an
MLR fermentation as most of my juices are reasonably but not too
acidic.Will this sulphite addition protect the wine (usually stored in
glass demijohns)if I keep it for a couple of years?

So,in summary,I am clearly suffering oxidation problems and plan to
add sulphite either

(i)both immediately after pressing(and then hope the natural yeast
gets going after a delay) and then after first racking or
(ii)just after first racking

I would very much like some advice.

Best regards
Michael