Clear or milky white liquid with a sulfurous odor.
Sodium bisulfite is used in almost all commercial wines, to prevent
oxidation and preserve flavor.
Sodium bisulfite releases
sulfur dioxide gas when added to
water or products containing water. The sulfur dioxide kills yeasts,
fungi, and bacteria in the grape juice before fermentation. When
the sulfur dioxide levels have subsided (about 24 hours),
fresh yeast is added for fermentation.
Sodium bisulfite (usually with an acid like
citric acid to make it produce gas
faster) is used to sterilize winemaking equipment.
It is later added to bottled wine to prevent oxidation (which makes
vinegar), and to protect the color of the wine from oxidation,
which causes browning. The sulfur dioxide displaces oxygen in the
bottle and dissolved in the wine. Oxidized wine can turn orange or
brown, and taste like raisins or cough syrup.
In fruit canning, sodium bisulfite is used to prevent browning
(caused by oxidation) and to kill microbes.
sodium bisulfite: InChI=1/Na.H2O3S/c;1-4(2)3/h;(H2,1,2,3)/q+1;/p-2/fNa.O3S/qm;-2 sulfur dioxide: InChI=1/O2S/c1-3-2
By Simon Quellen Field