µBrews – Episode 8

Using an adequate pitch rates is critical to ensuring a healthy fermentation, while for some styles of beer, lower pitch rates are needed to ensure the yeast produce the desired flavour profile. Ensuring a correct pitch rate requires the ability to accurately determine the concentration of yeast in a yeast sample. This is done by counting yeast, using a specialized slide called a hemocytometer.

In this video I will explain what a hemocytometer is, how it works, demonstrate its correct usage, and walk you through how to calculate the concentration of yeast in a yeast pitch from hemocytometer counts. At the end of the video I will demonstrate how a hemocytometer can be combined with viability staining (trypan blue staining), thus allowing you to quickly and easily determine both the number of living yeast in your sample and your samples overall viability.

This is part of a video series on using microscopy in the home or craft brewery. A full list of published episodes can be found on my µBrews YouTube playlist, or on my blog.

6 thoughts on “µBrews – Episode 8

  • July 2, 2021 at 5:12 am
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    Hi Bryan

    Hope you can and have time to help me with a yeast counting problem. I might not be the only one with that problem.

    I think my cell counting number is too small, so I decided to test it using an known sample.
    I bought a yeast packet from Whitelabs WLP013 London ale. From https://yeastman.com/info I got the exact count for the sample 2.15*10E9 cells/ml
    As expected my count was less than half 96x10E7 (480x200x10000)

    I am using an hemocytometer Neubauer depth 0.1mm area 0.0025mm2
    Dilute the sample 200 times (1ml yeast slurry to 9ml water, and 1ml from first step to 9ml water, and 1ml from second step to 1ml methylene blue)
    Then I count the 25 squares in the center square and got close to 500 cells. I did that severel times with same result.
    I take precautions to be very accurate in taking the sample, dilute and counting.

    What might be wrong?

    Regards Michael

    Reply
    • July 6, 2021 at 7:02 am
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      Your count is likely correct. The number of yeast in yeast suppliers packets can vary greatly, and typically the actual amount is within 1-log (e.g. +/- 10x) what it states on the package. Having half the stated amount is pretty consistent, and you probably have done the counts correctly. Also, keep in mind that when diluting as much as you are, even small mis-measurements can lead to a large mis-count, as the serial dilution “amplifies” any errors.

      Reply
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  • February 27, 2020 at 5:45 am
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    Bryan,
    Thanks for teaching.

    I think you misspoke in section 4.41~ (actually 4.48 ~ 4.51) where you say “zero point five” I think you wanted to say “point zero five”.

    the math works better that way i think

    Reply
    • February 27, 2020 at 1:16 pm
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      Yep, that was an error. I’ve added a pinned comment to the video pointing out the correct value.

      Reply

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