On 29 Jan, 06:41, wrote:
The use of suphite for the protection of your wine is all dependant on
the style and future consumption of your wine. If you want a wine to
last longer in bottle you are going to require an addition of sulphite
to protect your wine. When to add sulphite it depends on pH and the
use of indigenous yeasts. THe lower the pH the less likely you will
suffer oxidation issues. The lower the temperature of storage the less
oxidation issues you will have. The less ullage in your filled bottles
the less oxidation you will have. Ullage is the amount of airspace in
your bottle. Use a combination of these when storing your wine and it
will last longer.
Because you are not using a foregien yeast i would not reccomend using
sulphites before fermentation because this will limit your sucess
during fermentation. However it is very important that you use
sulphites immediately after fermentation finishes or just before the
end of ferment if you want to retain some residual sugar. This is the
most important time to protect your wine from oxidation and thus
prevent future oxidation. It is essential you know your sulphur levels
so the sulphur kit is also good advice. At bottling i reccomend at
leat 15-20ppm of free SO2. Maybe a little higher because your probably
not bottling with an inert gas cover. Its ok to oxidise before
fermentation even hyper oxidation has shown to have merits but after
primary fermentation especilly if you not going through Malo you must
use sufficient quantities of Sulphites to protect your wine and
monitor its progression, ie if you rack you will lose some free SO2
thus making your wine more susceptible to oxidation, good luck and
great wine,
SDH
Bachelor of Viticulture and Oenology

Thanks for that very clear piece of advice.I probably will continue to
wash the grapes,ferment on natural yeast and add sulphite after the
fermentation has finished,just as you describe.I tend not to bottle
but rack the wine into 1 gallon demijohns-at this point I intend to
sulphite.One final point.When you say add 15-20ppm of free SO2,is that
very approximately 0.5 Campden tablet/gallon or 0.1g of metabisulphite/
gallon?I am a little confused after reading all the science about
molecular SO2,free SO2,total SO2,bound SO2.
Thanks again
Michael