The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Avoiding mould in yeast water

mwilson's picture
mwilson

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

DanAyo's picture
DanAyo
  1. Minimise headspace - fill container to the top with fruit and water
  2. Use an air lock - the only issue with that is the increased over all height that makes the unit too high for a proofer, but there are some work arounds for this
  3. No airlock? Use a breathable closure to reduce humidity. A cloth and an elastic band will do. - I don’t understand how a breathable material will keep oxygen out of the head space
  4. Weigh down the fruit so that is kept well away from the surface - good idea, how could this best be done
  5. Cover the surface water. Use oil perhaps or a layer of clingfilm. - would a 1/4” of vegetable oil work? I guess enough to cover the surface, including the raisins that might bulge through the surface. The fermentation gas would bubble up and pass through the oil barrier and vent into the atmospher. The YW could be siphoned off from below the level of the oil. Cling film sounds easy and good
  6. Remove the headspace. How about using a balloon?! Inflate it so that completely fills the headspace. - balloon sounds viable, but concerned about the balloon as the YW ferments and produces lots of gas.

__________________________________

My best idea and current method

Use a small jar so the the fruit and water are 1/4” from the top. PlaCe a laatex glove over the jar and then depress the glove and at the same time vent the glove so that excess oxygen is purged. Once complete the glove will be sucked into the jar. With this method the glove is able to expand greatly as the fermentation produces gas.

Any thoughts, pro or con about any or all of the above?   

   

Danny

By the away - I checked the PH on all 4 of my test YW aNd they tested 3.5-4 with unreliable (full range 14 step) litmus paper. Can’t find my 3-5 PH test strips :(

JBT's picture
JBT

Thank you for this! I've already implemented some of these ideas.

Mini Oven's picture
Mini Oven

rotating the surface fruit under several times a day.  This seems to do the trick for me.

dsb66's picture
dsb66

Use a fermentation system like "The Easy Fermenter" (https://nourishedessentials.com/products/the-easy-fermenter). It has a very simple airlock lid, and the included pump allows removing air from the jar. I haven't tried it with raisins, but it works well for sauerkraut.