Antioxidant (and anti-bacterial) Highly recommended. 

It has been used in wine making since early Egyptian and Roman times.

Potassium Metabisulfite: an anti-oxidant and anti-bacterial additive. The recommended rate is 20 to 40 OR 50 ppm, the lesser amount for reds (as it has bleaching characteristics) or wines you want to undergo a malolactic fermentation.  “Meta” is added at racking. It can also be used for cleaning and chasing chlorine rinses.

Red wine is dosed with meta at the rate of 1/8 teaspoon per 5 gallons for 20 PPM.

White wine is dosed with ¼ teaspoon per 5 gallons for 40 ppm.

CALCULATING SO2 ADDITIONS  (POTASSIUM METABISULFITE) 576% (0.576) OF POTASSIUM METABISULFITE IS ‘ACTIVE’
Example: to add 50 ppm to 100 L
Desired addition (g/L)* volume (L)/0.576=grams of Meta to add
50 ppm = 50 mg/L = 0.050g/L
0.050*100 (liters)/0.576=8.6 grams of meta to add to 100L for 50ppm

100 Liters is 26.42 gallons

The LEGAL (USA) limit is 350 ppm.  You are safer using it than drinking contaminated wine. 


Do NOT use if planning a malolactic fermentation. The sulfur level must be 10-20 ppm or less for malolactic bacteria to survive. If you are planning a malolactic fermentation and are comfortable without its use, then go without.

Campden Tablets are a tablet form of Sodium or Potassium Metabisulfite for use in small lots. One tablet is 75-120 ppm in 1 gallon. We have seen ratings using both numbers. It makes us wary. Read the  label.

To further prevent oxidation, keep your fermenting vessel topped up to minimize the air space as much as possible.  Keep it topped up, using wine, not water.

Use an airlock, keep the water level in it high enough.  Check that the bung and airlock unit have not been knocked off.

 

IF your wine is oxidized, fine it with pvpp: polylact or polyclar.  This fining agent reduces browning and enhances flavor.