One of our regular requests for help in both winemaking and beer brewing, are queries on infections.
Most of the time, a simple photo shows us that it's just a foam on the top or some yeast clumps floating about.
Other times it’s an off smell, usually when someone is making cider. They complain of it smelling of a sulphur, eggy smell. That’s quite normal. It’s usually because the yeast are a little stressed, but the yeast will consume the compounds making those aromas and transform them into something a lot more palatable.
Another regular concern is due to the lid has being lifted too many times (by curious eyes) once the fermentation is near it's end, and the oxygen that has been allowed to enter the fermenter has allowed a pellicile to form. A thin layer of a type of bacteria that forms connections on the surface called a bio film. The bubbles are trapped CO2 from the fermentation.
Again, nothing to really worry about, just syphon off the wine and use a syphon sock to prevent the scum being sucked up. Then hit the wine with some campden tablets (1 tablet for each gallon (4.5 litres) of wine) and leave for 24 hours before moving to the next stage in the winemaking process. And next time, try not to lift the lid and let the fermentation do it's thing.
Infections are rare, but, the one that causes most distress and hard to rectify, is usually found when making wine. Suddenly during the fermentation, the wine froths up uncontrollably and spills out everywhere in a thick gloopy foam. Once the foam settles down, the wine is thick, gloopy, with slimy, snot like veins running through it. Everyone always tells us that they have sterilised everything thoroughly. So how could it have been infected?
Well we know the likely cause. It’s either a dishcloth used to get the steriliser on all parts of the equipment, or it’s a tea towel they have used to dry everything. Not thinking that the dishcloth and tea towel could be heavily infected with bacteria.
Yes, the sterilisers are good at doing their job, but if you have something like a used tea towel that has been hanging around in the kitchen for a few days, being used to wipe down the counter, wipe up a dish and even to dry hands, that tea towel can be heavily colonised with bacteria. Too many germs for the steriliser to work in such a short time to kill them all.
The wine gets infected before the yeast can start fermenting. The bacteria (Pediococcus) work fast and start forming long chain polymers. When the yeast eventually get going, creating CO2, it gets trapped by these polymers and the wine starts to foam. The alcohol the yeast create now subdues the bacteria, but the damage has already been done. An infected wine.
You can add campden tablets (Sodium Metabisulphite) to break down these polymers to make the finished wine more palatable, but it will have a buttery flavour and extra viscosity.
The best way to prevent an infection if you are using a cloth, is to use disposable cloths. We use a new one for each fermentation. It can then be used in the kitchen afterwards if you want to give it a longer life. Just make sure you use a fresh one if you are going to use a cloth when brewing.
Available in all supermarkets, these should be in everyone’s brewing cupboard in a sealed container to prevent contamination.
And there should not be a need to dry anything with a tea towel and if you have to, then use disposable paper kitchen towels.
So remember, sanitising is great, but if you use something like a cloth that has been used before, even if it looks clean, might not be. And sanitising might not kill all the germs on that cloth.
If you want to use a cloth from the kitchen, boil it first in some sterilising solution.
This also goes for straining bags, if you are using them. Boil them for a minute in some sterilising solution, rinse under cold tap water and use straight away.
Infections in beer happen a lot where a brewers has used a straining bag to dry hop a beer.
Anyway hope this helps article saves some wine and beer from being thrown away or worse, spilled over a living room carpet.
Cheers & Happy Brewing.