Potassium Metabisulphite

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IOC High Purity Potassium Metabisulphite is commonly used in must and wine for its antioxidant, anti-oxidase and antimicrobial agent.  It increases polyphenols extraction.


10-30 g/hL in must according to grape conditions, 2-5 g/hL in wine, at clarification, racking or after filtration; 10-15g / HL to preserve sweet wines. 1g of Potassium Metabisulphite releases approximately 0.56g of S02.
Warning: For maximum dosages, refer to current applicable laws.

Instructions for Use:

Disolve in a small amount of water, juice or wine and add to the must or wine to be treated.


Sealed Package: keep the product in a fresh, dry well ventilated area.  Opened Package: carefully reseal the package and keep as above indicated.  Hygroscopic product.

Pack and Pack Size:

  • 1Kg net weight plastic bag

Health and Safety Warning:

E 224 Pure Potassium Metabisulphite K2S2O5

C.A.S. number 16731-55-8


  • Causes serious eye damage
  • Wear eye protection / face protection: wear eye glasses with side protection.
  • IF IN EYES: Rinse cautiously with water for several minutes.
  • Remove contact lenses, if present and easy to do.
  • Continue rinsing.
  • Immediately call a doctor / physician.

    Contact with acids liberates toxic gas.

    Used Barrel Storage, Maintenance and Preparation:

    The holding solution is prepared using 1 tsp of citric acid and 1.5 tsp of potassium metabisulfite for each gallon (4 L) of barrel volume. For example, for a 15-gallon (57 L) barrel, use 15 tsp of citric acid and 23 tsp of potassium metabisulfite. (Note: 3 tsp = 1 tbsp) Dissolve these in one gallon of hot water.

    Fill the barrel two-thirds with water, add the holding solution, top up the barrel with cool water, and bung the barrel. Top up the barrel with a holding solution once a month to replace solution lost by evaporation and absorption into the wood. The barrel can be stored indefinitely without the risk of spoilage.

    During storage, rotate the barrel 45° in either direction every time you top up to keep the bung area soaked. This will prevent the bung area from drying out and protect it from spoilage organism growth. Caution: The sulfur-citric holding solution will etch a concrete floor. Rinse the floor with water to prevent this.

    Used barrels require no special preparation beyond a simple water rinse, if desired, when transferring wine out and in immediately. If the barrel has been stored with a holding solution, drain the barrel and rinse it thoroughly with clean water before transferring wine into it.

    Further Reading and information on:

    E 224 Pure Potassium Metabisulphite K2S2O5

    Potassium Metabisulfite (K2S2O5) or E 224, commonly abbreviated KMS, is a powdery, white, strongly sulfurous-smelling (burned match) chemical used in many food and beverage industries, as well as in breweries as an antioxidant. When dissolved in water or beer, KMS releases free sulfite ions, and these are responsible for the antioxidative properties of the compound. KMS is by far the most popular antioxidant used in the brewing industry. Its popularity within some large breweries is because it is highly effective at preventing oxidation and because the added sulfites improve the naturally occurring sulfites produced by the yeast during fermentation. KMS is also active in limiting growth of wild yeasts and bacteria in beer.

    Free sulfite reacts very readily with and thus eliminates free oxygen in foods (including beer), but also with many intermediary chemicals compounds (most important, aldehydes and ketones) that can combine with free oxygen into the stale and papery-tasting compounds so undesirable in beer.

    KMS is allowed by Food Health and Safety authorities in most countries (it has the E-number 224 on the EU positive list of food additives) around the world, but it is not permitted by Germany’s Reinheitsgebot (the German Purity Law, which is not, however, despite its name, an official law). KMS is rarely used by craft brewers anywhere, but it is common in mass-market beers in many countries. In most countries the use of KMS is regulated by specific limits either to the total concentration of sulfites in beer or by maximum allowed dosing rates. The reason for these limitations is that sulfites are known to provoke and worsen certain allergies in humans. For example, in the United States, levels above 10 ppm will require the words “contains sulfites” to be printed on the label.

    KMS is very widely, almost universally, used in the wine industry for the same purposes as in brewing, but in wine KMS is used at concentrations 10–20 times higher than in beer.


    Ilett, D. R.Aspects of the analysis, role, and fate of sulphur dioxide in beer—a review. Master Brewers Association of the Americas Technical Quarterly 32(1995): 213–21.  Anders Brinch Kissmeyer Craft Beer & Brewing Magazine