Author Topic: Just say "no" to yeast rinsing  (Read 16706 times)

Offline klickitat jim

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Re: Just say "no" to yeast rinsing
« Reply #45 on: July 16, 2014, 03:42:26 PM »
I went back and re listened to Brew strong episode on yeast rinsing because I started wondering why a guy who knows so much about it that he wrote the yeast book, would do rinsing... in the middle somewhere, JZ does mention that he racks the beer, tyen swirls the yeast into suspension in the remaining beer, flames the carboy opening, then transfers the yeast to a sanitary vessel. He stores it like that, on the beer. He then rinses prior to pitching.

I missed that part when I was rinsing. I would rinse on racking day and store in the rising water. In any even, I never noticed a marked improvement in my final product from rinsing so I quit doing it. I also limit my re pitching to about 3 generations.

On this subject im doing the denny method and calling it good enuff for me.

S. cerevisiae

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Re: Just say "no" to yeast rinsing
« Reply #46 on: July 16, 2014, 08:10:14 PM »
I use 91% and 70% isopropyl alcohol.  I use 91% isopropyl alcohol when culturing because it burns much better than 70% isopropyl alcohol (I use borosilicate glassware almost exclusively).  I use 70% isopropyl alcohol to wipe down the table that I use when conducting aseptic transfers because it is much cheaper than 91% isopropyl alcohol.


I do not know if this study is dated, but it appears to be interesting research related to the subject. 

http://www.ncbi.nlm.nih.gov/pubmed/9801287


"Surgical hand disinfection with alcohols at various concentrations: parallel experiments using the new proposed European standards method.
Rotter ML1, Simpson RA, Koller W.
Author information
Abstract
OBJECTIVES:

To establish the concentration of isopropanol that exerts the same immediate and sustained effects as n-propanol 60% v/v in surgical scrubbing, and to assess the performance of the test method proposed as the European standard in parallel experiments.
DESIGN:

Isopropanol at concentrations of 70%, 80%, and 90% v/v was tested in comparison with n-propanol 60%, the proposed reference preparation, in the draft method proposed by the European standard. A Latin square design was used with four balanced blocks of five volunteers each in four experimental runs that were spaced by intervals of 1 week each. Volunteers were allotted randomly to one of the four blocks. Independently, the volunteers' right and left hands also were randomized into two groups for the assessment of either immediate or sustained effects.
SETTING:

Two laboratories supervised by two investigators, one from Vienna, Austria, and one from London, The United Kingdom.
METHOD:

The release of skin flora from the fingertips of clean hands was assessed before and after treatment by immediate sampling from one hand and by sampling of the other, gloved hand after 3 hours. The mean log10 reductions (RF) of bacterial release achieved by rubbing the alcoholic preparations for 3 minutes onto the hands were established.
RESULTS:

For both experiments, the immediate effects of isopropanol 70% (RF, 2.0 and 2.1, respectively) were significantly smaller than those of the reference n-propanol 60% (RF, 2.4 and 2.6, respectively). This also was found with the sustained effects (RF, 0.7 and 1.1 vs 1.0 and 1.6, respectively). At 90%, isopropanol equalled the immediate effect of n-propanol 60%, whereas at 80% it proved slightly (although not significantly) less active. There were no significant differences in the results of both investigators. The sustained effects of isopropanol 80% and 90% were both larger than the reference in Vienna but were found smaller by the London investigator; none of the differences were significant. Mean RFs were significantly different between Vienna and London with n-propanol 60% and isopropanol 70%, but not with isopropanol at 80% or 90%.
CONCLUSIONS:

At 90%, isopropanol is as effective as n-propanol 60%, which was proposed by the European Committee for Standardization as a reference in testing products for surgical hand disinfection. It could, therefore, serve as an alternative if the proposed agent is undesirable for any reason. In parallel experiments by two investigators, the proposed test method proved well workable; the results were very similar and the conclusions identical.
"

« Last Edit: July 16, 2014, 08:40:22 PM by S. cerevisiae »

S. cerevisiae

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Re: Just say "no" to yeast rinsing
« Reply #47 on: July 16, 2014, 08:16:36 PM »
He then rinses prior to pitching.

If a brewer is going to rinse, the time to do it is right before pitching, as the yeast culture does not spend a long period of time in a nutrient-free, high-pH solution.

By the way, I believe that Jamil only wrote the more applied parts of Yeast.

Quote
On this subject im doing the denny method and calling it good enuff for me.

It's the not the Denny method.  I use basically the same method (see paragraph number 4 of the original post in this thread), and so does every other experienced brewer that I now.
« Last Edit: July 16, 2014, 08:41:34 PM by S. cerevisiae »

Offline klickitat jim

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Re: Just say "no" to yeast rinsing
« Reply #48 on: July 16, 2014, 08:33:44 PM »
For several months I've been doing it that way. Now I know that Denny also does it that way. Hopefully when I refer to it as the Denny method, no one loses any royalties.

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Re: Just say "no" to yeast rinsing
« Reply #49 on: July 16, 2014, 08:40:06 PM »
The idea is that the water is required for protein denaturation. High concentration alcohol is extremely hygroscopic (i.e., it draws water out of solution, the air, etc.). The end result is that it could potentially dry out the cell membrane, preventing its ability to enter the cell. The quoted range of concentrations where alcohol is generally considered most effective is in the 60-80% range, and effectiveness falls off rapidly below 50%.

You brought up an important concept that we can tie to fermentation.  The reason why we oxygenate wort at the beginning of fermentation is that yeast cells use oxygen in the production of ergosterol and unsaturated fatty acids (UFA).  Ergosterol and UFAs make yeast cell membranes more pliable.  As yeast cells take in nutrients and expel waste through their cell membranes, a pliable cell membrane is critical to cell health.  It is also critical to alcohol tolerance.  Yeast cells stop fermenting beyond a certain percentage of alcohol because of what you mentioned; namely, the hygroscopic nature of ethanol.   Basically, yeast cells are unable to pass nutrients and waste through their cell membranes because they become dehydrated.

Offline tommymorris

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Re: Just say "no" to yeast rinsing
« Reply #50 on: July 16, 2014, 09:52:00 PM »

For several months I've been doing it that way. Now I know that Denny also does it that way. Hopefully when I refer to it as the Denny method, no one loses any royalties.

Now I am confused. Where do I send my check?


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Offline erockrph

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Re: Just say "no" to yeast rinsing
« Reply #51 on: December 14, 2014, 06:40:05 PM »
This thread has been referenced so often that we should consider making it a sticky.
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Offline bboy9000

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Re: Just say "no" to yeast rinsing
« Reply #52 on: December 15, 2014, 04:23:55 AM »

Can you define your entire process for us S?  Ill try it, the only reason i was rinsing is because it was the most used method i could find instructions for.


One habit that all brewers should get into is the habit of wiping all pouring surfaces with a cotton ball soaked with 95% ethanol

So just spraying the surfaces with Star San isn't good enough? 
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Offline morticaixavier

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Re: Just say "no" to yeast rinsing
« Reply #53 on: December 15, 2014, 03:56:51 PM »

Can you define your entire process for us S?  Ill try it, the only reason i was rinsing is because it was the most used method i could find instructions for.


One habit that all brewers should get into is the habit of wiping all pouring surfaces with a cotton ball soaked with 95% ethanol

So just spraying the surfaces with Star San isn't good enough?

not for yeast ranching. If you're just repitching once or twice it's not a big deal but if you are going to be culturing from a couple million cells it becomes more important to get as close to sterile as possible and star san doesn't do that.
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Offline erockrph

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Re: Just say "no" to yeast rinsing
« Reply #54 on: December 15, 2014, 04:09:41 PM »

Can you define your entire process for us S?  Ill try it, the only reason i was rinsing is because it was the most used method i could find instructions for.


One habit that all brewers should get into is the habit of wiping all pouring surfaces with a cotton ball soaked with 95% ethanol

So just spraying the surfaces with Star San isn't good enough?

not for yeast ranching. If you're just repitching once or twice it's not a big deal but if you are going to be culturing from a couple million cells it becomes more important to get as close to sterile as possible and star san doesn't do that.
+1 - It mainly depends on your definition of "good enough". If you're going to be pitching right into another batch in a day or two, then it's probably good enough. But any miniscule contamination will increase over time. When you're talking about long-term storage or smaller culture sizes, then contamination can take over much more easily. Alcohol will sterilize, while Star-San will not guarantee sterility.
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Offline Jimmy K

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Re: Just say "no" to yeast rinsing
« Reply #55 on: December 15, 2014, 05:07:12 PM »

One habit that all brewers should get into is the habit of wiping all pouring surfaces with a cotton ball soaked with 95% ethanol
I'm a biologist, but not a microbiologist. I heard several years ago that 70% ethanol sterilizes better than 95% ethanol because the water helps denature cell proteins. I don't remember where I heard this, so any idea if it's true?
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Offline HoosierBrew

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Re: Just say "no" to yeast rinsing
« Reply #56 on: December 15, 2014, 05:14:28 PM »

One habit that all brewers should get into is the habit of wiping all pouring surfaces with a cotton ball soaked with 95% ethanol
I'm a biologist, but not a microbiologist. I heard several years ago that 70% ethanol sterilizes better than 95% ethanol because the water helps denature cell proteins. I don't remember where I heard this, so any idea if it's true?

I read the same from a few sources several years back (don't remember the source).  I remember references to the 70% causing more disruption to the cell walls. Maybe it does that by interaction with the proteins (?).
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Offline erockrph

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Re: Just say "no" to yeast rinsing
« Reply #57 on: December 15, 2014, 06:02:54 PM »

One habit that all brewers should get into is the habit of wiping all pouring surfaces with a cotton ball soaked with 95% ethanol
I'm a biologist, but not a microbiologist. I heard several years ago that 70% ethanol sterilizes better than 95% ethanol because the water helps denature cell proteins. I don't remember where I heard this, so any idea if it's true?

That's the theory. The idea is that 95% ethanol is so hygroscopic that it could potentially dehydrate the cell membrane before the ethanol can pass into the cell. I've never seen any experimental data proving this, however. Still, if I were to start yeast ranching in earnest, I would probably use 70% ethanol, or maybe 151-proof rum as my sterilization agent.
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Re: Just say "no" to yeast rinsing
« Reply #58 on: December 15, 2014, 06:51:47 PM »
I use 70% to wipe down my work surface.  I use 91% isopropyl or 95% grain alcohol for wiping any surface that will be flamed.  I also keep my loop immersed in 91% isopropyl or 95% grain alcohol between inoculations while subculturing or plating (I use a culture tube filled with alcohol).   I usually start a culturing session by flaming the loop until it is red hot.  From that point forward, I merely pull the loop out of the culture tube that is filled with alcohol, ignite the alcohol, and then perform the transfer as soon as the alcohol burns off.  The process results in sterile loop that requires much less time to cool to a temperature where it no longer fries the cells on contact.

Offline bboy9000

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Re: Just say "no" to yeast rinsing
« Reply #59 on: December 15, 2014, 10:13:17 PM »
So the mason jar of Pacman stored under a beer layer that's been in my fridge for 4 months may not be good?  That stuff is hard to get here in Missouri now that BrewCraft has opened the east coast warehouse.  They don't carry Pacman but that's the warehouse that ships to KC.
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