Comparing E223 - Sodium metabisulphite vs E228 - Potassium bisulphite
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Popular questions
Is sodium metabisulfite bad for you?
For most people it isn’t “bad” at the low levels used in foods, but sulfite‑sensitive individuals (including some asthmatics) can have reactions such as wheezing, hives, or headaches. Regulators set a group ADI for sulfites of 0–0.7 mg SO2 equivalents per kg body weight per day.
Is sodium metabisulfite safe?
Yes—E223 is an approved preservative/antioxidant when used within regulated limits, though sulfites must be declared on labels and can trigger adverse reactions in sensitive people and some asthmatics.
Is sodium metabisulfite gluten free?
Yes. It’s a synthetic inorganic salt and contains no gluten; any gluten risk would come from other ingredients or cross-contact, not the additive itself.
What is sodium metabisulfite used for?
It’s used as an antioxidant and preservative to prevent browning and microbial spoilage in foods and drinks (e.g., wine, cider, dried fruits, seafood, potato products), and as a sanitizing agent for winemaking/brewing equipment.
How much sodium metabisulfite per gallon of wine?
To add about 50 mg/L (ppm) SO2 to 1 US gallon, use roughly 0.28 g sodium metabisulfite (about half a sodium Campden tablet); winemakers typically target 25–50 ppm free SO2 depending on pH and often use potassium metabisulfite instead.
How are bisulfite ions generated in the iodine clock reaction potassium iodate and sodium sulfite?
Bisulfite (HSO3−) comes either directly from dissolving potassium bisulfite (KHSO3 → K+ + HSO3−) or by protonation of sulfite from sodium sulfite in acidic solution (SO3^2− + H+ → HSO3−), which is the pH range used in the iodine clock.
How does sodium bisulfite and potassium iodate react to make iodine reaction with starch?
In acid, iodate (IO3−) oxidizes bisulfite (HSO3−) to sulfate while being reduced to iodide; once bisulfite is depleted, remaining iodate oxidizes iodide to iodine (I2), which then forms the blue complex with starch.
How does sodium bisulfite and potassium iodate react to make iodine reaction with starch equations?
Key steps (acidic medium): IO3− + 3 HSO3− → I− + 3 SO4^2− + 3 H+; then IO3− + 5 I− + 6 H+ → 3 I2 + 3 H2O; and while bisulfite remains, it removes iodine: I2 + HSO3− + H2O → 2 I− + HSO4− + 2 H+.
How long is potassium bisulfite good for?
Stored airtight in a cool, dry place, solid potassium bisulfite is typically usable for about 1–2 years; in solution it loses strength much faster (weeks to a few months) as it oxidizes to sulfate.
How most potassium bisulfite or metab?
Potassium metabisulfite (E224) is more commonly used because it’s more stable, but both it and potassium bisulfite (E228) release SO2; for dosing, KHSO3 is ~53% SO2 by weight and K2S2O5 is ~58%, so slightly less metabisulfite is needed to achieve the same SO2 level.