In brewing, we always tell you to sterilise equipment before use to make sure your brew does not become contaminated. But what can contaminate your brew? 3 things really. Yeast, bacteria and mould.
Mould is easily dealt with and can be killed using a chlorine based steriliser, but it's usually a sign that you have put your equipment away wet or have been keeping it somewhere damp.
There are thousands of strains of yeast and some of them can create unwanted flavours or mouth feel. So to be sure you get the brew you want, you need to stop these yeast from taking hold and potentially ruining your brew. So it’s best to kill or subdue these until your chosen yeast becomes the prominent sugar muncher in the brew.
Who knows how many types of bacteria they are in the world, but unless you are making a sour beer, or something funky, then they aren’t normally wanted when brewing. So it’s best to stop them at the beginning. Once there is approx 0.5% alcohol in your beer or wine, that’s usually enough alcohol to kill most bacteria. However there are a few strains of bacteria that love alcohol. So you need to be careful not to get these into your beer or wine as you’ll soon have vinegar. This is why you need to sterilise all equipment that is going to come into contact with your brew including hydrometers, spoons and siphon to name a few.
So now you know why we are sterilising, the next thing you need to think about is which type of steriliser you are going to use. There are various types, and the all have their advantages. We can put them in to 4 main categories: Chlorine Based; Acid Based; Sodium Metabisulphite; Sodium Percarbonate. So now a little bit more info on each..
But, before we continue, a word of caution. These chemicals should be used as directed on their labels and this is a guide only. Never be tempted to use a stronger concentration than directed. These are chemicals that can be harmful, toxic and even fatal if not used correctly so follow the instructions on the container.
Chlorine Based – These are usually called Cleaner & Steriliser and contain chlorine that kills the bacteria and also bleaches the surface so makes brewing buckets brilliant white and bottles sparkle.
- For bleaching, items have to be immersed in the solution for at least 10 minutes and up to 24 hours.
- For sterilising, you have to make up the solution, then coat all surfaces with the liquid, which you then leave for 10 minutes. Items do not have to be submersed in the liquid, but the surfaces must be wetted by the solution.
Chlorine can taint and cause off flavours when brewing beer and wine, so items need to be rinsed with cold tap water or a weak Sodium Metabisulphite solution.
Acid Based - No Rinse – These use acid to kill the bacteria. They are normally in liquid form (but can come in powder form) that you have to dilute with water – use as directed. Do not be tempted to make a stronger solution.
They are convenient as it can be put into a spray bottle and you can spray the surface that you want sterilised and you don’t need to rinse it off either.
If you live in a hard water area (if you have lots of lime scale in your kettle), then you will need to buy distilled water or soft water to dilute the acid or the calcium in the water can neutralise the acid.
For sterilising, spray or coat the surface of the item needing to be sterilised, then leave to fully dry. Items have to be left to fully dry before use.
Sodium Metabisulphite – This has been used for many years by home brewers. This technically does not kill yeast, but prevents them from multiplying.
At the same time it is a deoxidiser, so helps prevent oxygen from discolouring fruit and prevents beer from going brown.
It is also used to protect wine and beer from infection by airborne bacteria as it creates a layer of Sulphur Dioxide above the wine or beer. This gas, when it comes into contact with a mucus membrane, turns to sulphuric acid and this is what kills any bacteria trying to get into your brew. Bear this in mind when using, as this should be used in a well ventilated area or you too will suffer the effects of the sulphur dioxide in your lungs and it will make you cough a lot.
Campden tablets are a prescribed amount of sodium metabisulphite in a tablet form, which means it is very easy to get the perfect dosage when adding to 4.5 litres (1 UK gallon). Recipes usually say to add a campden tablet to the fruit juice (or must or wort) and leave for 24 hours. Sodium metabisulphite subdues any natural yeasts, prevents bacteria from multiplying, removes the oxygen and creates a protective layer of gas on top of the liquid. You can then pitch your commercial yeast which gets to work, multiplying and then eating the sugar and making alcohol with the flavours that you want to create. By the time the alcohol content is 0.5% ABV, this is usually enough to kill bacteria that would be bad for your brew. This also lets the natural yeasts do their funky thing in the background adding their flavours and characteristics to your brew, but with your choice of yeast to do the hard work. If you just pitch your yeast without the campden tablet, bacteria can get to work on your liquid before the ABV is high enough to kill them. The bacteria can start to add an unwanted sourness to your wine or beer.
- For Sterilising, use 1 tsp Sodium Metabisulphite (or 10 crushed campden tablets) to 1 pint of water. Stir to dissolve, then use the solution, to coat all surfaces with the liquid, which you then leave for 10 minutes. Items do not have to be submersed in the liquid, but the surfaces must be wetted by the solution. After 10 minutes, rinse the items with cold tap water.
- Using as a deoxidiser, use 1 crushed campden tablet to 4.5 litres of must / wort. You must leave it for 24 hours to do it’s thing. Do not pitch your yeast until after the 24 hours, of your yeast will be subjected to the effects of it too.
Sodium Percarbonate – No Rinse – Usually in a water soluble powder, you need to make up the solution, then coat the surface of the item needing to be sterilised, then leave to fully dry. This can take up to 1 hour and in that time it breaks down in to non toxic substances. The Sodium Percarbonate breaks down into hydrogen peroxide and Sodium Carbonate. The hydrogen peroxide, which acts as a bleaching agent and kills the bacteria, further breaks down to water and oxygen, so is no toxic, so no rinsing is required. However the sodium carbonate can look like a white film on the inside of clear bottles, so some users of this type of steriliser still like to rinse in off. Items have to be left to fully dry before use.
So in summary, which do you use and when?
I would suggest having 3 types in your brewing tool kit.
1 - Sodium Metabisulphite is great to use to sterilise clean buckets, spoons, hydrometers etc before you start brewing as you just have to make up a small amount to coat all the surfaces, leave for 10 mins, rinse and you are ready to go.
2 - Chlorine based sterilisers are great to clean and sterilise your buckets after you have used them, so they are ready to go on your next brew. Even if you are planning to put them into storage for a while, it’s best to put them away clean. Using the cleaner & steriliser will help prevent the build up of a bio-film. To do this you will need to make up enough solution for fill your vessel, so can use a lot of cleaner & steriliser. A bio-film is where bad bacteria can survive with no moisture for years and this will help prevent your next brew becoming contaminated right from the start. Sometimes that bio-film can be a real pain to clear and sometimes, the only way is a new fermenting vessel.
These are also good to sterilise your equipment before use, as you can wet all surfaces and leave for 10 minutes too, then remember to then use Sodium Metabisulphate to get rid of the chlorine taint. And then rinse.
3 - Acid based sterilisers are amazing when you are bottling a large amount of bottles. Make up a solution and put it into a bottle rinser (like the spin vinator). Squirt the liquid up into the bottles and leave upside down on a draining rack to dry naturally, then bottle your beer, wine or cider with no worries of contamination.
Also great if you have time on your hands to let items dry before using them, or your equipment is large or difficult to reach spaces due to the fact you can use a spray bottle to administer it.
Final Note...
A final note on using other sterilisers that you find in the supermarket such as Milton Sterilising Tablets, that were not designed for use in homebrew, more for sterilising baby bottles in cold water.
Some of these may contain chemicals (or concentrations) that interact with others in your brew. These can create some unwanted off flavours. People that use Milton as a steriliser in homebrew regularly report their brew has a chlorine like smell, or a soapy flavour.
In my opinion, it is best to use a cleaner & steriliser designed for brewing and then follow the instructions as per the container.