Chem 101

[cuz]

Can someone explain the different uses and terms of all the SO2.Is all this stuff SO2

potassium metabisulfite
Potassium Sorbate
sulfites
sorbates
SO2

Which is used for sterilization
Which is used for killing wild yeast
which is used for killing bacteria in the wine. When should this be used. (Read something about every 3 months of bulk aging.)
which is used to stabilize the wine and prevent a further fermentation.

 

[Ajmassa]

This really is a great question. It's not always spelled out in a way for someone starting out to understand easily.

Potassium sorbate or 'sorbates' is the one used to stabilize thenwine preventing further fermentation. ----this is the only use for potassium sorbate in winemaking. (No need for it if you ferment all the way dry leaving no residual sugar and are not sweetening later)

Everything else mentioned is pottassium metabisulphite/sulfite/So2/k-meta --all the same thing.
Larger quantities (2-3 oz. per gallon of water is used for sanitizing (not sterilizing--nothing is really needed to be sterilized ever. Just sanitized)
Smaller amounts added to wine kills bacteria and protects the wine. Many people check the level of So2 to maintain the proper amount which dissipates over time.
Therefore you are correct in making a sulfite addition every 3 months to make sure the wine is protected. About 1/4 tsp per 6 gal. (A bag of pottassium metabisulphite also has these 2 ratios printed right on the bag. One to kill wild yeast/bacteria/protection. And the other for sanitizing )

Easily confusing to just about anyone starting out.

 

[cuz]

Thank you

That simplifies things

 

[richmke]

to add to what AJ wrote:

Sorbate keeps the yeast from multiplying. It doesn't do anything to yeast/bacteria already there. If you let a wine ferment to dry, and do not back sweeten, then you don't need Sorbate (nothing to allow yeast to grow).

SO2, in high enough concentrations, will kill yeast (killing wild yeast prior to fermentation). SO2 will also "protect" the wine from oxidation by binding with free O2.