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Absolute yeast filtration of kombucha

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  • Absolute yeast filtration of kombucha

    Hi,
    I am a very small scale commercial kombucha brewer. 1000L per month, batch size 250L. Gradually upscaling.
    My kombucha is pure tea, no 2F. I would like to create ambient shelf stable product hence need to remove all yeast (with minimal impact on flavour and colour) prior to carbonation and bottling.
    I currently rely on CO2 passing kombucha between corny kegs using a 1 micron depth filter.
    Can anyone recommend the best solution for filtration? Next upscale will give batch size of 500L and then 2000L. Plan is to rely on CO2 and corny kegs for the time being until growth allows for brite tanks, etc.
    Many thanks
    Jo

  • #2
    Look at the Buon Vino Super Jet (not the mini jet). It ought to be just about perfect for your needs. I think they run about $350-400 USD.

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    • #3
      Thanks UnFermentable.
      I'm reading on-line that only up to 80% of yeast is removed using sterile pad 3. This would leave me with a potentially unstable product.
      Do you know of other options that would remove ALL yeast?
      As I am based in a hot climate with poor chilled distribution and storage I need to do my utmost to create a stable product.
      Many thanks
      Last edited by theaveragejo; 04-06-2020, 02:09 AM.

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      • #4
        The average size of a Saccharomyces cell is about 3-5 microns in size. Brettanomyces can be even smaller. A sterile filtration will be around .45 microns. Anything claiming sterile filtration should be able to remove all yeast (and eukaryotes) at least, or it is not sterile.

        Bacteria can be as small as .2 microns, meaning even “sterile” filtration does not completely guarantee it’s removal. Very few bacteria and cysts are smaller than .45 microns making that the shelf for “sterile” filtration.

        Filter media is often rated as absolute or nominal. Absolute will “guarantee” you pull nothing larger than the rated micron size, while nominal cannot “guarantee” all particulate below the micron rating will be removed.

        You Kombucha makers are using a combination of yeasts and bacteria. Micro-stability is dependent on the level of micro organisms present (CFU’s) and the level of metabolic activity those organisms are allowed to achieve (food & environment). Reducing log factors should be step one (filtering is great), but there are other methods for stabilization as well such as pasteurization or sulphites that should strongly be considered if you expect a long shelf life and extreme stability.

        Ultimately you will need to perform your own stability tests for your product after you implement your program . No manufacturer is going to promise you stability.

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        • #5
          Thanks UnFermentable,
          Can you please clarify what 'reducing log factors' means?

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          • #6
            Log reduction is the measure of living organisms that have been eliminated by disinfection, sanitation, pasteurization,
            etc. This is referring to the ratio of Colony Forming Units (CFU) both before and after your given procedures.

            A 1 log reduction is equivalent to eliminating 90% of CFU’s. A 2 log
            reduction would be 99%, and so on.

            In light of the current situation, a specific example might be “disinfecting” your silverware. (Off memory), I believe you need something like a 6 log reduction in less than 10 minutes to meet EPA guidelines for disinfection? Someone may be able to add more.

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            • #7
              Thank you for clarifying this

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