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Looking at this video I had the idea of vacuum sealing yeast that I harvest from my beer batches to better protect it from bacteria/mold.

My plan is to rinse the yeast with boiled (sanitized) water and store it in that water (so it won't produce CO2).

Since I'm not a biologist I'm wondering if that is a good idea, if anyone has done that before and if there are any downsides.

In special, I would like to know if such a setup would make it easier to anaerobic bacteria to infect my harvested yeast (which I would like to avoid).

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  • I don't know the advantages myself, but I would think this is overkill.
    – Scott
    Commented Jul 30, 2013 at 0:55
  • @Scott Why so? The process is the same for regular harvesting + a 10 seconds extra to pump the air out of of the glass container... If that increases the potential storage time I think It could be worth it
    – Cleber Goncalves
    Commented Jul 30, 2013 at 5:55
  • From what I've heard, so long as you take the proper precautions in cleaning your yeast, you shouldn't have much of a concern. The way I think of it is, if there's any bacteria in the minimal quantity of air in the capped mason jar, by the time I could have removed the air, it would have already fallen into the liquid, rendering the whole process useless. I'm sure it can't hurt, but from those who have taken the proper precautions, it seemed uncommon to worry about what little bugs may be in the minimal air-gap in the jars.
    – Scott
    Commented Jul 30, 2013 at 6:03
  • Actually, reading over your comment more, I highly doubt this would have any impact on the shelf life of the yeast. The yeast typically is good for 6 months, before a (larger than normal) massive starter is necessary to compensate, and even then, it may be too old to be of much use. Removing oxygen from the canister will most likely have minimal impact on the preservation of the yeast.
    – Scott
    Commented Jul 30, 2013 at 6:05
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    Are you planning to store this in the freezer with glycerine or just store in the fridge?
    – mdma
    Commented Jul 30, 2013 at 11:32

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I don't think this will make it easier for anaerobic bacteria - they are not really affected by the presence or lack of oxygen, and since there is little food available I doubt they would propagate anyway.

I don't think it will do any harm, but you may want to try harvesting two jars yeast at the same time both with and without a vacuum to see if there really is any improvement in shelf life.

It's possible to have yeast remain uncontaminated for a long time without a vacuum - this brewer states he's stored yeast for 17 months in the fridge without issue - but of course he doesn't mention how many (if any) he's lost to contamination so this is anecdotal at best.

Homebrewing is a highly personal process - if it works for you, no reason not to do it!

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  • How would one homebrewer measure shelf life of yeast in these conditions? Best I can see is a wort split in half, using both jars, one in each batch and measure attenuation. The more attenuative wins for future batches. Is there a more scientific approach?
    – Scott
    Commented Aug 1, 2013 at 3:34
  • I was thinking about spoilage/contamination - mould/bacteria, since that was the specific concern the OP had. Leave both jars (vacuumed and non-vacuumed) in the fridge for 3-4 months and see if there is any noticable pelicle/mould.
    – mdma
    Commented Aug 1, 2013 at 10:37
  • Actually, anaerobic bacteria are defined by their ability to grow in the absence of oxygen. Obligate anaerobes are killed by oxygen. Facultative anaerobes can grow in environments with or without oxygen. Regardless, if there was contamination in the first place the presence or absence of a vacuum would not change that factor but a low oxygen environment would prevent aerobic spoilage organisms from growing.
    – RudyB
    Commented Aug 22, 2013 at 18:39

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