it is the molecular sulphur dioxide content of free sulphide dioxide that
protects wine from oxidation and microbial attack. the content of molecular
sulphur dioxide in the free sulphur dioxide depends on the pH of the wine
with lower pH's having the higher content. eg. pH 3.0 = 6% , pH 4.0 = 0.6%
therefore it would seem to me if u r using metabisulphite as a sanitising
agent for equipment and bottles it is useless unless the water used is
acidified to at least below a pH of 4.0.
any comment?
neil