Sodium Metabisulphite: What It Is & How to Use It in Home Brewing
Share
Sodium metabisulphite is one of the most useful chemicals in home winemaking. It's the active ingredient in Campden tablets, and in powder form it's a cheap, versatile way to protect wine, treat water and rinse equipment.
What Is Sodium Metabisulphite?
It's a white powder that releases sulphur dioxide (SO₂) when dissolved. SO₂ does two jobs:
- Antimicrobial: suppresses wild yeast and spoilage bacteria
- Antioxidant: protects wine from oxidation, which causes browning and stale, sherry-like flavours
Campden tablets are simply pre-measured tablets of the same chemical, with one tablet dosing one gallon. The powder is better value for larger batches and for making up rinse solutions. For more on the tablets, see Should I Use Campden Tablets?
What It's Used For
1. Preparing fruit must
Added to crushed fruit or juice before fermentation, it knocks back wild yeast and bacteria so your chosen yeast can take over. Wait 24 hours before adding yeast, or the SO₂ will inhibit it.
2. Protecting finished wine
A small dose at racking and before bottling helps prevent oxidation and spoilage. Before back-sweetening, use it with potassium sorbate.
3. Removing chlorine from water
It neutralises chlorine and chloramine in tap water, which otherwise cause medicinal off-flavours in beer. See our brewing water guide.
4. Rinsing equipment
Winemakers traditionally use a sulphite solution to rinse equipment. It's useful, but weaker than modern sanitisers, so use it alongside a proper sanitiser rather than instead of one. Compare options in our sanitiser guide.
How Much to Use
Doses vary by job and product, so always follow the instructions on the pack. A little goes a long way: too much can leave a sulphurous smell and taste.
Safety
- Don't breathe in the fumes when mixing solutions; SO₂ is sharp and irritating, particularly for people with asthma.
- Sulphites are a recognised allergen, so bear that in mind if giving wine to friends.
- Never mix with chlorine-based products or acids in concentrated form.
- Keep the container sealed and dry, and out of reach of children.
Which Product to Buy
- Campden Tablets (100) – pre-measured, one per gallon
- Sodium Metabisulphite 100g
- BrewCo Sodium Metabisulphite 100g or 500g
- Handcraft Supplies Sodium Metabisulphite 100g
Frequently Asked Questions
What is sodium metabisulphite used for in wine making?
To suppress wild yeast and bacteria in fruit must, protect finished wine from oxidation and spoilage, remove chlorine from water, and rinse equipment.
Is sodium metabisulphite the same as Campden tablets?
Campden tablets are pre-measured tablets of metabisulphite. The powder is the same chemical, measured by weight.
How long should I wait before adding yeast?
About 24 hours after adding it to must, so the SO₂ level drops enough for your yeast to start.
Can I use it to sterilise equipment?
It's a useful traditional rinse for wine equipment, but weaker than modern sanitisers. Use it alongside one rather than instead.
Is sodium metabisulphite safe?
Yes, at winemaking doses. Avoid breathing in the fumes when mixing, and note that sulphites are an allergen.