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
Washing Yeast with Chlorine Dioxide?
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So I did some research and the research shows that you want a 20-40 ppm concentration to kill any bacteria. At that concentration it will only kill bacteria and NOT yeast. The water purification tabs are good for 4ppm in 1L. 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. Apparently this method is becoming popular in the pro brewing world as an alternative to acid washing.
oldstyle69
Well-Known Member
let us know how it goes. sounds like a decent plan.
WoodlandBrew
Well-Known Member
very interesting! Acid washing is another reasonable way to clean 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.
Here is a what a brewing supplier says....
WASHING OF YEAST SLURRY WITH OXINE: Stabilized ClO2 (Oxine) will effectively kill unwanted bacteria in yeast at 20 to 40 ppm, while leaving the culture yeast unharmed. Because of stabilized ClO2's unique action, it does not have the drawbacks of phosphoric acid. It does not form chlorophenols (which contribute to a much feared medicinal character in products) in the presence of organic materials.
YEAST WASHING METHOD: Normally, an initial washing at 20 to 40 ppm (20 ppm for homogenous yeast, 40 ppm for "clumpy" or highly flocculant strains) is effective against most Lactobacilli and Pediococci species. This "wash" is done by adding stabilized ClO2 directly to yeast slurry on a volume/ppm basis. It does not need to be activated as the pH of the yeast slurry is low enough to convert to ClO2.
Stabilized ClO2 is supplied at a concentration of 20,000 ppm or 2% Chlorine Dioxide when activated. Therefore, on a volume basis, one could essentially make up with one gallon of stabilized ClO2 concentrate, one thousand gallons of solution at 20 ppm. By this method, we can also assume with one gallon of concentrate to make up one thousand gallons of yeast slurry at 20 ppm. It is impractical to measure the concentration of ClO2 in the presence of yeast, so the dilution must be made based on the strength of the concentrate (20,000 ppm).
Yeast slurry should be thin enough to allow for homogeneous mixing, usually 20 to 40% solids. The killing action of stabilized ClO2 is very fast compared to the traditional phosphoric acid wash. Only 15 to 30 minutes need be allowed for effective bactericidal effect of stabilized ClO2, with no resultant stress on yeast cells.
YEAST WASHING DOSING RATE: For regular washing of homogenous recycled brewers yeast, a 20 to 40 ppm wash for a minimum 30 minutes to 5 hours prior to pitching. Mix 1 to 2 ml of stabilized ClO2 concentrate with each liter of yeast slurry. Agitate thoroughly during the process.
Here is a what a brewing supplier says....
WASHING OF YEAST SLURRY WITH OXINE: Stabilized ClO2 (Oxine) will effectively kill unwanted bacteria in yeast at 20 to 40 ppm, while leaving the culture yeast unharmed. Because of stabilized ClO2's unique action, it does not have the drawbacks of phosphoric acid. It does not form chlorophenols (which contribute to a much feared medicinal character in products) in the presence of organic materials.
YEAST WASHING METHOD: Normally, an initial washing at 20 to 40 ppm (20 ppm for homogenous yeast, 40 ppm for "clumpy" or highly flocculant strains) is effective against most Lactobacilli and Pediococci species. This "wash" is done by adding stabilized ClO2 directly to yeast slurry on a volume/ppm basis. It does not need to be activated as the pH of the yeast slurry is low enough to convert to ClO2.
Stabilized ClO2 is supplied at a concentration of 20,000 ppm or 2% Chlorine Dioxide when activated. Therefore, on a volume basis, one could essentially make up with one gallon of stabilized ClO2 concentrate, one thousand gallons of solution at 20 ppm. By this method, we can also assume with one gallon of concentrate to make up one thousand gallons of yeast slurry at 20 ppm. It is impractical to measure the concentration of ClO2 in the presence of yeast, so the dilution must be made based on the strength of the concentrate (20,000 ppm).
Yeast slurry should be thin enough to allow for homogeneous mixing, usually 20 to 40% solids. The killing action of stabilized ClO2 is very fast compared to the traditional phosphoric acid wash. Only 15 to 30 minutes need be allowed for effective bactericidal effect of stabilized ClO2, with no resultant stress on yeast cells.
YEAST WASHING DOSING RATE: For regular washing of homogenous recycled brewers yeast, a 20 to 40 ppm wash for a minimum 30 minutes to 5 hours prior to pitching. Mix 1 to 2 ml of stabilized ClO2 concentrate with each liter of yeast slurry. Agitate thoroughly during the process.
WoodlandBrew
Well-Known Member
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?
smakudwn
Well-Known Member
After washing with the ClO2 could you then store said yeast for a couple of months?
That is exactly what I used!! I still have some vials of the "contaminated" yeast. I will grow them up and "wash" them in the same manner and let you see the difference. I am excited to see the difference!
zmad2000
Well-Known Member
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.
You can pickup those tablets at almost any sporting goods store. I have a liquid form called aqua mira.
Just make sure that the tablets are chlorine dioxide and NOT iodine. They have both types. I almost picked up the wrong ones.
As far as long term storage of yeast.....I don't know. I think the safest way to go is to use the tablets 30 minutes- 4 hours before pitching the yeast.
zmad2000
Well-Known Member
Yeah i think doing it at the start of the brew day and then pitching it at the end would be fine.
dbals
Well-Known Member
Curious on any updates..... Could one treat their yeast and freeze, using glycerin?
zmad2000
Well-Known Member
It worked out well for me. No off flavor or anything.
If you going to treat yeast for freezing then make sure that the chlorine dioxide is very weak. It is meant to kill micro organisms so if the yeast are exposed too long to it they will die.
If you going to treat yeast for freezing then make sure that the chlorine dioxide is very weak. It is meant to kill micro organisms so if the yeast are exposed too long to it they will die.
I just washed some more yeast with Chlorine Dioxide right before pitching into a Double IPA. I went up to 50 ppm(roughly). It seemed a little slower to start.....12 hours vs. my normal 8 hours. Happily fermenting away right now......
WoodlandBrew
Well-Known Member
I washed some yeast with star sans recently and saw a longer lag that without, but they both attenuated the same.
Just a quick update.....I had some of my harvested yeast that was "washed" with the chlorine dioxide tested for viability. It had been sitting in a vial for 5 weeks. There was no noticeable decrease in viability....other than might be expected from it being 5 weeks old and no visible contamination. I will continue to use the tabs whenever I wash my yeast as a cheap way to keep the yeast contamination free.
BigdogMark
Well-Known Member
I washed five yeast pitches this past Saturday before throwing into fermentors. I was using half-pint jars, and each had 100 ml of densely packed yeast plus water to the top. I put one crushed tablet in each jar. All five batches showed evidence of fermentation after 12 hours and very active after 24. The yeast was a rinsed harvest from about 4 weeks ago stored in the fridge. I had another harvest go bad with a definite off smell over the same period. This one seemed fine but did the treatment anyway. I should know in week or so if the brews turn out good.
el_caro
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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?
I don't think so. When I add the tabs there is some liquid present...in fact you want some liquid(beer) because it helps keep the ph low. The tabs dissolve pretty quickly plus I have mine on a stir plate.
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.
Another update on my washed yeast with chlorine dioxide......Pulled some 002 out of the fridge that had been washed with chlorine dioxide and then stored for 4 months. I made a starter and after 36 hours on the stirplate I have gotten ZERO attenuation.....nothing. The chlorine dioxide must have been toxic to the yeast....at least for that length of time. Still a viable option though as long as you use it right before pitching.
biertourist
Well-Known Member
I just read the "yeast care" page of the Brewing Science Institute and they state VERY SPECIFICALLY that they find chlorine dioxide as the IDEAL way to "wash" yeast of all bacterial infection; they clearly state that it is both better at killing bacteria AND leaves behind more healthy yeast than acid washing.
http://www.brewingscience.com/yeast_care.htm
Adam
http://www.brewingscience.com/yeast_care.htm
Adam
biertourist
Well-Known Member
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
dstar26t
If it's worth doing, it's worth overdoing
I'm researching using Chlorine Dioxide for yeast washing and stumbled upon this post. Here's another reference for those doing the same. Trying to come up with a SOP that I am comfortable with. Crushing up the tablet by hand and adding it to the slurry doesn't sit well with me. Also, it appears that ClO2 boils at 11ºC (52ºF) so keeping everything cooler seems necessary. I might try making a super concentrated solution with sterile water and then dose the decanted slurry with the correct volume to reach 20-40 ppm while keeping it all under boiling point.
dbals
Well-Known Member
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.
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.
biertourist
Well-Known Member
Wow, I stand corrected. Thanks for posting this.
Still seems insanely labor intense, though. But I guess you don't have to wait for things to grow on a plate, though.
Adam
balauru_327
Active Member
Hello,
I know i`m off topic, but do you consider "washing " with etilic alchool 90%? What i mean is to add alchool to obtain a 10% ABV in the slurry, or washed yeast. I tryed recently, and i had great results. I will try to infect a yeast, and see how it goes.
I know i`m off topic, but do you consider "washing " with etilic alchool 90%? What i mean is to add alchool to obtain a 10% ABV in the slurry, or washed yeast. I tryed recently, and i had great results. I will try to infect a yeast, and see how it goes.
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.
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.
fantomlord
Well-Known Member
so it sounds like you would add 20-40 ppm ClO2 to your starter a few hours prior to pitching? Doest the ClO2 need to be a certain temp to kill the bacteria? Or can I throw it in, and then cold crash for a few hours prior to pitching? Or throw it in at room temp for a few hours, then cold crash, decant, and pitch?
Also, is it necessary/helpful to wash your starter with plain water (boiled and cooled, of course) prior to pitching to remove the ClO2, or does the gas evolution during fermentation carry it out?
I'm dealing with lacto in my wild captured yeast, and I'd really like to save it.
Thanks!
The Experimenter
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This is an older thread, so I'm not sure if anyone will see this, but I have a question on this topic. I know the OP was about using Aquatabs to wash harvested yeast, but could you use water purification chemicals like those in Aquatabs or Potable Aqua to kill yeast IN a brew, such as to stop a fermentation early or to just make it drinkable (without cold crashing, pasteurizing, or using other chemicals like metabisulfite or sorbates)?
I normally just cold crash my brews to force the yeast into a state of dormancy because a couple of people in my family are really sensitive to the yeast, so if they drink a non-cold crashed brew they get upset stomachs. I have pasteurized before, but that takes a lot of prep time and careful monitoring of temperature. I have also used metabisulfite and sorbates, and while they are pretty reliable, they don't actually kill the yeast but instead prevent them from reproducing and there is always a chance that they could come back (it's rare in my experience, but it can happen).
Then, one day while prepping my 1-liter nalgene bottle and a few Chlorine Dioxide Potable Aqua tablets for a backpacking trip, it dawned on me... If these tablets are used for purifying drinking water of bacteria, viruses, and fungi, could I just toss a couple of them into the fermenter to kill off the yeast prior to bottling?
I normally just cold crash my brews to force the yeast into a state of dormancy because a couple of people in my family are really sensitive to the yeast, so if they drink a non-cold crashed brew they get upset stomachs. I have pasteurized before, but that takes a lot of prep time and careful monitoring of temperature. I have also used metabisulfite and sorbates, and while they are pretty reliable, they don't actually kill the yeast but instead prevent them from reproducing and there is always a chance that they could come back (it's rare in my experience, but it can happen).
Then, one day while prepping my 1-liter nalgene bottle and a few Chlorine Dioxide Potable Aqua tablets for a backpacking trip, it dawned on me... If these tablets are used for purifying drinking water of bacteria, viruses, and fungi, could I just toss a couple of them into the fermenter to kill off the yeast prior to bottling?
- According to Potable Aqua, their Chlorine Dioxide tablets improve the taste and odor of water (not sure what that "improvement" would do to a brew though). While Chlorine Dioxide is supposed to be a broader spectrum kill than their normal PA tablets, from what I understand it actually is not that effective against yeast unless given long exposure time.
- These things considered, Potable Aqua's PA tablets would probably be better. They supposedly don't affect the taste or odor of water assuming you use the PA+ tablets afterwards and the chemicals in the PA tablets (which are mostly Iodine) CAN kill yeast, supposedly more effectively than Chlorine Dioxide according to what I've read.
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