Just curious if anyone does this when harvesting yeast? It seems like a cheap, easy way to help get the cleanest slurry possible. Here's the link from the NB catalog http://www.northernbrewer.com/shop/chlorine-dioxide-tablets-20-ct.html
That's great! Did you use Potable-Aqua tablets from Northern Brewer? At less that 50c a wash that sure beats buying new yeast! I've been working on comparing various washing techniques for some blog posts. Do you mind if I cite your results?
Will be trying this on my next brew day which is going to be this weekend.
You can pickup those tablets at almost any sporting goods store. I have a liquid form called aqua mira.
My plan is to decant off my starter to the 300 ml level and add two tablets. That should give me roughly 25-30 ppm. You let this mix for 15 minutes and then pitch the yeast into your wort.
Very interesting.
Would you not need to mix the tabs with water to get the desired 25-30 ppm before adding the yeast to the solution? Could just adding tablets to the starter result in localised high concentrations before tablets dissolve and mix thoroughly and that might harm the yeast?
Just a quick update....It seems like washing the yeast with chlorine dioxide was a success! I used some yeast that I knew was slightly contaminated. WoodlandBrew was kind enough to run some test on my yeast before the "wash"...http://woodlandbrew.blogspot.com/search/label/lab report I used the WL002 for a Brown Porter. Racked into the kegs and it tasted great. No sourness at all. Just to confirm my results I will send him some of my "washed" yeast for comparison.
Just another update...the Brown Porter with the "washed" yeast scored a 41.5 in the first round of the NHC. A guy in my homebrew club looked at my washed yeast in the microscope. He couldn't find any evidence of contamination.
A guy in my home brew club looked at my washed yeast in the microscope. He couldn't find any evidence of contamination.
I LOVE this test that you're doing and don't want to get you down, but that's definitely not a valid way to test for bacterial infection; you'd need to add some of your slurry / wort to an lmda culture plate and see what grows after a few days. --You're looking for a needle in a haystack.
Having said all that I DEFINITELY agree that using chlorine dioxide to "wash" yeast is a great way to go, I'd love to see us get the dosage and other parameters locked in. -What if you perform yeast "rinsing" and you have highly carbonate water, would this increase the ph enough that you'd need to increase the dosage of cl dioxide / it wouldn't be effective?
-What happens to the chlorine when you pitch it into your beer? -Do we really want chlorine dioxide in our beer? Can we not add distilled water and decant off most of this stuff?
Will the chlorine react with stainless to cause pitting over time? -Should the washing be performed in glass or plastic for this reason?
Adam
Accord to the ASBC Methods of Analysis it is the accepted way to detect presence of bacteria in the section Yeast 2B:
Dilute yeast, view under at least 600X and count at least 1,500 yeast cells
and report number of rods and cocci per 100 yeast cells. They do go on to say that this does not distinguish between viable and nonviable bacteria and one should go onto plating for that.
This subject came up during a Brewing Micro course at UC Davis. While Chlorine Dioxide is very effective against bacteria, it will kill the yeast given enough contact time. This should not be done for stored yeast.
The Chlorine Dioxide should only be used for washing fresh slurry that will be immediately repitched. This is true for acid washing also. I know many people acid wash, then store yeast but that is not what acid washing was developed for.
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