Avoiding mould in yeast water
Managing headspace, or ullage as it known is the primary job for any winemaker.
The headspace is the perfect environment for mould growth and mould must absolutely have oxygen to grow.
Don't make the mistake in thinking that by simply putting a lid on it, this makes the contents anaerobic. Not so. The air in the headspace is the same air as that outside of the jar. Also the use of a tight enclosure will create a headspace that becomes humid and this further improves the environment for mould growth.
With that in mind here are some ideas:
- Minimise headspace
- Use an air lock
- No airlock? Use a breathable closure to reduce humidity. A cloth and an elastic band will do.
- Weigh down the fruit so that it is kept well away from the surface
- Cover the surface water. Use oil perhaps or a layer of clingfilm.
- Remove the headspace. How about using a balloon?! Inflate it so that completely fills the headspace (see illustration below)
- Stir or shake frequently. This will mix up the liquid and breakup its surface which will inhibit mould from forming in its prime location.
- Use carbonated water. Carbon dioxide will gradually fill the headspace and may help to discourage mould growth.
Not all of these suggestions can be used together and they are just my thinking out loud ideas. Have a go..
Hopefully this might help