Many of the old, traditional wine making books (not that anyone reads books anymore) talk about using sulphite solutions for sanitization. And with popular alternatives like Star San having taken over the world, you might wonder if sulphite solutions can indeed be used as sanitizers, or if this was just old-timey lore.
As it turns out, in fact, sulphite solutions can be used as effective sanitizers for home wine-, cider- and mead making. Sulphite solutions can be made from either potassium metabisulfite or sodium metabisulfite, and both work well to prevent contamination by killing bacteria, wild yeast, and other unwanted microorganisms.
How to Use a Sulphite Solution for Sanitizing
- Prepare the Solution:
- Dissolve 4 tablespoon (50 grams) of potassium metabisulfite or sodium metabisulfite in 1 gallon (3.8 liters) of warm water.
- Sanitize Equipment:
- Thoroughly rinse or submerge all equipment in the sulphite solution. Make sure all surfaces come into contact with the solution.
- Contact Time:
- Allow the equipment to stay in contact with the solution for at least 10 minutes.
- Drain Well:
- Drain the equipment well. No rinsing or air drying is necessary, so you can use the sanitized equipment right away.
Well, if you really want to geek out about things, here’s how sulphite solutions work for sanitizing winemaking equipment: It's all about the SO₂. How many times have I said that? SO₂. I have a tee shirt that reads "It's the SO₂, Dummy!"
- Release of Sulphur Dioxide (SO₂):
- When potassium metabisulfite (K₂S₂O₅) or sodium metabisulfite (Na₂S₂O₅) is dissolved in water, it releases sulphur dioxide (SO₂) gas. This gas is the active sanitizing agent.
- The chemical reaction for potassium metabisulfite in water is:
K2S2O5 + H2O → 2KHSO3
KHSO3 → K+ + HSO3−
HSO3− + H2O → H2SO4 + SO2
- (Damn, Neidermeyer, you're a geek. How 'bout you just give me your lunch money right now so I don't have to kick your ass.)
- Similar reactions occur with sodium metabisulfite, so don't ask me to repeat the chemistry. Plus, I have no more lunch money.
- Antimicrobial Properties:
- Inhibits Microorganisms: SO₂ is highly effective at inhibiting the growth and activity of a wide range of microorganisms, including bacteria, wild yeasts, and molds. It works by disrupting their metabolism and enzyme function, leading to cell death. Hey, they weren't invited to the winemaking party. They knew what they were getting into, so I say let them die.
- Chemical Environment:
- pH Impact: SO₂ is more effective in acidic environments (lower pH), which is typically the case in wine and cider making. The acidic environment enhances the antimicrobial activity of SO₂.
- Residual Protection: Even after initial sanitation, a small amount of residual SO₂ remains on the surfaces of the equipment, providing ongoing protection against microbial contamination.
The Many Benefits of Using a Sulphite Solution
Well, they won't do your taxes or help you save for retirement, but they have other useful applications:
- Effective Broad-Spectrum Sanitizer: I hate to use the term "broad-spectrum" because it reminds me of the crazy stuff I put on my front lawn, but oh, well... Anyway, sulphite solutions are effective against a wide range of unwanted microorganisms, and by wide range, I mean I don't want any of them.
- No Rinsing Required: After sanitizing, there is no need to rinse the equipment with water, as the small amount of residual SO₂ will not harm the wine and will help in preserving it.
- Easy to Prepare and Use: Sulphite solutions are easy to prepare and use. Yeah, well so is Star San, but if it's the zombie apocalypse and I don't have any Star San around, then I'm using my sulphite solution. Just saying.
So now you know how a sulphite solution can effectively sanitize your equipment and reduce the risk of contamination, leading to better quality wine. And after this chemistry demonstration, you'll need plenty of good quality wine to bribe the neighborhood bully not to take your lunch money.