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Potassium Metabisulfite 1 kg (35oz)#CH-10-3061 $18.95 |
Potassium Metabisulfite is a common additive used to preserve and stabilize wines, ciders, and occasionally beers. When added to wine or must, it forms sulfur dioxide gas (SO2). This prevents most wild microorganisms from growing and acts as a potent antioxidant, protecting both the color and delicate flavors of wine. Potassium Metabisulfite solutions are also used as sanitizing rinses for winemaking equipment.
Recommended
Usage
Dosage varies when used to kill wild bacteria in must, halt fermentation, or preserve finished wines against oxidation. The addition of ¼ teaspoon of potassium metabisulfite to 5 gallons contributes approximately 50 ppm of free SO2.
To make a sanitizing rinse for equipment, dissolve 8 teaspoons of potassium metabisulfite into 1 gallon of water. High concentrations of sulfur dioxide gas are irritating and toxic, so use in a well ventilated area. After applying the solution to your equipment, the items must be rinsed with clean, cold water.
Do not use to clean stainless steel !
Short effort to help clarify wine SO2 additions:
In the winery we target a "molecular" S02 threshold based on pH but also the alcohol level of the wine. The goal is to have sufficient free S02 in a molecular nonbound state to prevent spoilage from wild yeasts and bacteria such as S. cerevisiae and Brettanomyces. S. cerevisiae is inhibited at 0.8 PPM Molecular SO2 (measured in PPM against pH). Bacteria and Brett are inhibited at 0.4 PPM Molecular SO2 (again measured in PPM against pH).
Only this form of nonbound molecular S02 actually kills unwanted bacteria and non-Saccharomyces yeasts. The Molecular level is directly dependant on the pH of the wine. A pH of 4.0 takes 10 times higher concentrations of S02 to attain a .8ppm molecularity then a wine with a pH of 3.0. To confuse things more the molecularity needed is also influenced by Alcohol levels. Higher the alcohol the lower the molecular S02 need to achieve the desired outcome.
One tool I use regularly is the on line sulfite calculator from WineMaker Magazine. It allows the user to change the molecular target and calculate the amount of S02 need for a given wine. You just need to know the pH, wine volume, and it will tell you the targeted ppm given the molecular number you've selected.
Link to Winemaker Mag's online calculator:
http://winemakermag.com/1301-sulfite-calculator
We target .8 Molecular for low alcohol, white/rose, and/or sweet wines. We target .5 Molecular for higher alcohol ( < 14% ) red wines.
Your S02 calculations should not be a mystery regardless of the artistic license taken at harvest with Brix, TA, and pH selections.
Cheers!
