I started my first cider yesterday. I am concerned that, because I haven't pasteurised I am running the risk of getting 12 litres of vinegar.
Is there I anything I can do, now fermentation has started, to prevent that and how can I keep tabs on progress during the fermentation?
Topic vinegar contamination fermentation cider homebrew
Category Mac
I believe Acetobacter will spoil your product only if there is an oxygen present. So, to prevent that, good airlock would be enough. Once fermentation is in progress, there should be enough CO2 to push the air out, even if airlock is poor.
As fermentation slows down, CO2 will be produced in smaller quantities and demands to airlock qualities became higher. I generally fill my airlocks with some sulfite solution to prevent oxygen diffusion and I believe this is enough.
The test for acetobacter is simple: smell whatever's coming out of the airlock on your fermenter. If it smells like vinegar, you've got bacterial contamination ["an infection"] :).
For a fermentation in progress, there's only a couple of options. You could pasteurize the whole batch, which would kill off bacteria as well as the yeast, so you'd have to repitch your yeast.
Another possibility is to dissolve some campden tablets into your cider. If you pitched a quality, healthy yeast, they won't be affected by the increased sulfite concentration but it will inhibit bacteria and wild yeast growth. If you take this route and find fermentation stops, just give it some time and repitch, as the sulfites from the campden will dissipate with time. Campden tabs are used all the time in wine and cider making to prevent infection without having to boil/pasteurize.
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