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Acid washing yeast?

Hey folks,
I’m in the process of growing yeast from a Unibroue ‘La Fin du Monde’ bottle. It’s growing well, but today when I took a peek under the microscope(when I’m not brewing, I’m a Veterinarian) there are plenty of yeast but also plenty of bacteria. Smells and looks OK so far, but…
So, I’ve seen posts about acid washing yeast to decrease bacterial contamination, but haven’t found a technique. I also see that our host has Chlorine Dioxide tabs for sale that are labeled to decrease bacterial contamination.
Has anyone used either? Have a technique you’d care to share?
Thanks a bunch!

https://www.google.com/search?q=How+to+ ... =firefox-a

The first 3 links look very informative.

Thanks Nighthawk!
I’m laughing at myself :lol: because while I searched here and on HBT fairly extensively, I didn’t even think of googling the topic.
Oh well, I guess I AM getting old after all…

Just finished looking at the links. The article by birko lab on using Chlorine Dioxide is perfect- just what I was looking for.
I’ve used ClO2 for disinfecting water on backcountry hiking trips, and just happen to be going to an outdoor supply store tomorrow before heading out on a weekend trip. So I’ll pick up some, and post my results after I use it.
Thanks again Nighthawk.

You’re welcome. Sometimes we miss the easy searches.

FWIW my understanding of acid-washing (usually phosphoric I think?) yeast is to kill off/smite the mother cells that have significant bud-scarring from reproduction/division(the scars don’t stand up to the acid), thereby increasing ‘viability’ (fertility?) of the yeast population.

Its all very genocidal if you think about it. :mrgreen:

Interested to know how your chlorine dioxide works out, please post back!

Acid washing is mainly to reduce contaminants, i.e. bacteria.

How much bacteria are you seeing? You would probably be better off isolating and starting a new culture.

Ok here’s the report:
The Acid washing looked too complicated, I didn’t have any phosphoric acid, and it looked like you were supposed to use the yeast right after washing and I wanted to store it. So Acid Washing was out.
Chlorine Dioxide I found easily in a Camping store. It’s called Aqua Mira, and consists of two bottles- the Chlorine Dioxide and an activator(phosphoric acid ironically enough). You mix 7 drops of both together, wait 5 minutes, then add to the water(or in my case yeast culture). Wait 1/2 hour, and you’re done.
I was going camping, so on Friday I coldcrashed the culture in the frig. decanted the supernatant and replaced it with cooled, boiled water.
Today, I took a sample pretreatment, then treated her as above, then took another sample.
Microscope report- there was still bacteria pretreatment, but it looked like fewer, probably because of the water wash. Bacteria is mostly gone post-treatment, and yeast still look viable. I replaced the water again with cooled, boiled water, and she is sitting in my frig.
Now my plan is to wait until Thanksgiving, finish off the two bottles of ‘La Fin du Monde’ I have sitting in the frig, and try to grow another culture. Then I’ll combine the two in a starter, do a saison or patersbier first, then brew the Belgian Triple as my New Year’s special.

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