Potassium Metabisulphite - 250g
Potassium metabisulphite is used to introduce sulphur dioxide into wine. Small quantities of sulphur dioxide are used to control wine microbes, and sulphur dioxide also reduces wine oxidation. When sulphite is added to wine, it produces about half its weight in SO2 (about one gram of sulphur dioxide is produced when two grams of sulphite are added to the wine).
Strong sulphite solutions are used to sterilise just about everything in a winery. One teaspoon of sulphite powder and two teaspoons of citric acid in two gallons of water makes an effective solution for sterilising equipment, and some home winemakers use this solution to sterilise bottles just before they are filled with wine. Inert, oak barrels can be stored full of water safely using a sulphite solution. One cup of citric acid and one cup of sulphite crystals are added, and then the barrel is filled with clean water.
Click here for a good article on the use of Potassium Metabisulphite.