The cold hard truth about rinsing yeast with boiled water

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EarlyAmateurZymurgist

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Let's start by defining the word "sterile." Boiled water is not sterile. It's more like hyper-sanitary. Sterile means that everything is dead, and moist 212F/100C heat does not kill spores. Water has to be raised to 250F/121C and held there for 15 minutes in order to render it completely sterile. As water boils at 212F/100C at normal atmospheric pressure (less at elevation), boiling isn't going to get the job done. We have to raise the pressure under which water is boiled to 15 pounds per square (psi) inch above normal atmospheric pressure in order to delay boiling until 250F/121C is reached. This process is known as "autoclaving." An autoclave is just a lab-grade pressure cooker. Most high-quality pressure cookers are capable of 250F/121C @ 15 psi above normal atmospheric pressure operation.

Yeast cells have two metabolic pathways. In the presence of oxygen and glucose concentration levels below the Crabtree threshold, yeast cells respire. During respiration, yeast cells consume a carbon source (e.g., sugar) and produce water and carbon dioxide gas. Above the Crabtree threshold, yeast cells switch into fermentation mode, regardless of dissolved oxygen level. During fermentation, yeast cells consume a carbon source and produce ethanol and carbon dioxide gas. Yeast cells take in dissolved oxygen while in fermentation mode via the respirative metabolic pathway; however, it is shunted towards the biosynthesis of sterols and unsaturated fatty acids necessary to make their cell membranes more pliable. Yeast cells obtain nutrients and expel waste products via their cell walls; therefore, a pliable cell membrane is critical to yeast cell health.

Let's discuss how a yeast culture goes about "owning" a batch of wort. In preparation for fermentation and fermentative growth, the pitched yeast cells rapidly consume dissolved oxygen, which prevents aerobic microflora from reproducing. The pitched yeast cells also lower the pH of the solution to between 4.1 and 4.2. Most types of bacteria are pH sensitive; therefore, they will not grow in an acidic medium. Finally, yeast cells produce ethanol as a waste product. Ethanol is toxic to most microflora. Brewing yeast strains have been domesticated to tolerate much higher ethanol levels than wild microflora.

Why is washing yeast with boiled tap water a bad idea? Well, as mentioned above, boiled tap water is not sterile. It also has a near neutral to alkaline pH, which raises the pH of the culture. Finally, boiled water does not possess the antiseptic qualities of ethanol. In essence, we strip away the force field that the culture built for itself and introduce a source of infection when we replace green beer with boiled water. Contrary to what many amateur brewers believe, a culture rinsed with and stored under boiled tap water does not go dormant. The culture remains in the stationary phase where it starves to death and cell autolysis provides an abundant source of nitrogen on which germinated spores can feast.

Is boiled wort is absolutely sterile? No, boiled wort is not absolutely sterile. However, it has an important quality that boiled tap water does not; namely, an acidic pH (usually around 5.2). As mentioned above, most bacteria are pH sensitive; therefore, spores that survive the boil will find less than hospitable conditions after the wort cools. Add in the fact that brewers usually pitch a mass of yeast cells that is large enough to make quick work of consuming dissolved oxygen, lowering the pH even further, and producing ethanol, and it will be difficult for any spore that survived the boil to germinate.

When it comes to yeast management, less is more. The best way to reuse yeast is to just crop and repitch. Commercial breweries reuse yeast this way every day. If one is trub and hop sensitive (this organic matter does not hurt the culture), the best way that I have found to bottom-crop a relatively clean yeast culture while leaving the culture's ecosystem intact is to leave enough green beer behind while racking to be able to swirl the solids into suspension after racking is complete. One should wait a few minutes to allow the heaviest particulate matter to drop out of suspension before carefully decanting about 250 to 300ml of the lightest fraction of the slurry into a sanitized 500ml Erlenmeyer flask or other suitable container. It is easier to perform this procedure when cropping from a transparent carboy than an opaque bucket. The culture can be stored in a refrigerator for up to a month without feeding (the culture should be vented); however, I would not go beyond that point without decanting the green beer and replacing it with fresh bitter wort because the culture will rapidly start to lose its viability.


With that said, one should always keep in mind that cropping is not an effective way to "bank" cultures. The most foolproof way to maintain a bank of cultures in a home brewery is on solid media in the form of agar slants. Yeast stored on slant can live up to two years without being subcultured onto new blank slants. I kept several difficult to obtain cultures alive for ten years using this method. I would still have those cultures today had I not taken an extended hiatus from the hobby. Anyone who is willing to put forth the effort can learn how to slant yeast and propagate yeast cultures from slants.
 
...the best way that I have found to bottom-crop a relatively clean yeast culture while leaving the culture's ecosystem intact is to leave enough green beer behind while racking to be able to swirl the solids into suspension after racking is complete. One should wait a few minutes to allow the heaviest particulate matter to drop out of solution before carefully decanting about 250 to 300ml of the lightest fraction of the slurry into a sanitized 500ml Erlenmeyer flask or other suitable container. It is easier to perform this procedure when cropping from a transparent carboy than an opaque bucket. The culture can be stored in a refrigerator for up to a month without feeding (the culture should be vented); however, I would not go beyond that point without decanting the green beer and replacing it with fresh bitter wort because the culture will rapidly start to lose its viability...

From you post in another thread (can't remember which one now) I have repitch yeast into a second batch with pretty much this method. Except I was suing clean and sanitised baby food jars and capped them - only to find they leaked some beer after a few days. Was wondering if that was due to Desolved CO2 in the beer escaping or something else (didn't think it would be from new CO2)?
Doing it the way you describe is a win-win, no more hassle of preparing cooled boil water in mason jars ready to go at bottling time and better for the yeast at the end of the day.
I had no issue grabbing the yeast from a bucket, just swirl, wait 5 mins, then pour slowly.

Cheers :mug:
 
Pictures! I need pictures!

Seriously, thanks for the in depth explanation.
 
From you post in another thread (can't remember which one now) I have repitch yeast into a second batch with pretty much this method. Except I was suing clean and sanitised baby food jars and capped them - only to find they leaked some beer after a few days. Was wondering if that was due to Desolved CO2 in the beer escaping or something else (didn't think it would be from new CO2)?


It's best to keep a cropped culture in a container than can be vented. I keep my cropped cultures in 500ml Erlenmeyer flasks with drilled #7 stoppers and air locks. As lab glassware goes, 500ml Erlenmeyer flasks are relatively cheap. One can usually pick up a six pack of 500ml Corning 4980s for around $30.00 shipped. If properly cared for, 4980s last a long time. I still have the first 4980-500 that I purchased back in 1993 for yeast culturing.

http://www.amazon.com/dp/B001424QKS/?tag=skimlinks_replacement-20


Doing it the way you describe is a win-win, no more hassle of preparing cooled boil water in mason jars ready to go at bottling time and better for the yeast at the end of the day. I had no issue grabbing the yeast from a bucket, just swirl, wait 5 mins, then pour slowly.

I am a firm believer in the KISS principle. While I plate, slant, and propagate my own yeast, I try to keep each step of the process as simple as possible without risking contamination.
 
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I've been doing it this way for years. Seems a waste of effort to wash yeast only to throw most of it away. Most papers I have read say yeast is keep best in the beer anyway.

I usually collect 3 pint mason jars from 7 gallon batch, store in fridge, and vent occasionally. I'll use one for a new brew, sometimes I'll use all 3 jars in separate brews, but usually throw out more than I use.

I partial mash/partial boil, so I have to add make-up water. I don't make a starter with the yeast, doesn't seem necessary if used within a month. I use some of the make-up water to wash the yeast on brew day, getting rid of most of the trub and dead yeast before pitching. My beers are usually chugging away within 8 to 14 hours.
 
I think the yeast washing illustrated thread needs the sticky removed. It's really not a good practice...

Sure, it works (usually) but there are lots of homebrewing techniques that work that really shouldn't be practiced.

I mean seriously, ~4oz yeast stored under a few tablespoons of beer, or 1-2oz of yeast stored under ~10+oz of water?

img_20140106_205840_954-61783.jpg
 
What would happen if you added citric acid to lower the ph of the wort to below 4.6? It would kill spores then. Would that be more favorable than using boiled water with a ph of 7? Obviously that has to be pressure canned, but wort is so close to the 4.6.

If the yeast temporarily lowers the ph to 41.-4.2, they would be able to survive in something 4.5. If you are decanting off said beer before pitching, or even if not if you have a small amount, I can't imagine the miniscule amount of citric acid would matter much. It couldn't be worse than using acidulated malt to adjust mash ph, could it?

I'm just thinking, why not adjust the starter wort to 4.5 before the boil and call it good. Same goes for the techniques of canning wort. Why not get it to 4.5 and hot water can it, just to be used for starters. I have a big old pressure cooker for canning, but many don't, and you could still hot water can much more efficiently in the time it takes to run the pressure canner once.

Edited: To avoid double post.
 
You make some good points here. Still, while there are some advantages to what you are recommending, I don't think yeast rinsing, as it is commonly described, is altogether a bad thing.

Zainasheff and White, in their book "Yeast" never seem to make your points in their discussion of yeast harvesting and they recommend that harvested yeast be rinsed. It is true that in their description of rinsing, they use the word "sterile" in reference to the rinse water. However, I don't think this is a significant concern. While boiled water is not technically sterile, neither is your fermented wort, carboy, storage vessel, or the air to which you expose your harvested yeast and wort during transfer. I doubt there would be significantly more contamination in boiled water than you would get otherwise during harvesting.

Of course, their recommendations should be viewed in context of their recommendation to reuse yeast very quickly, setting an outside bound of 2 weeks on storage. I'm guessing that your suggestion may be better if storing yeast for more than a few days.

If desired, pH could be easily adjusted before storage as well.

It has surprised me a bit how much of brewing science is still based on experience and conjecture, with different and sometimes contradictory recommendations given by respected authorities.
 
You make some good points here. Still, while there are some advantages to what you are recommending, I don't think yeast rinsing, as it is commonly described, is altogether a bad thing.

Zainasheff and White, in their book "Yeast" never seem to make your points in their discussion of yeast harvesting and they recommend that harvested yeast be rinsed. It is true that in their description of rinsing, they use the word "sterile" in reference to the rinse water. However, I don't think this is a significant concern. While boiled water is not technically sterile, neither is your fermented wort, carboy, storage vessel, or the air to which you expose your harvested yeast and wort during transfer. I doubt there would be significantly more contamination in boiled water than you would get otherwise during harvesting.

Of course, their recommendations should be viewed in context of their recommendation to reuse yeast very quickly, setting an outside bound of 2 weeks on storage. I'm guessing that your suggestion may be better if storing yeast for more than a few days.

If desired, pH could be easily adjusted before storage as well.

It has surprised me a bit how much of brewing science is still based on experience and conjecture, with different and sometimes contradictory recommendations given by respected authorities.

It is funny. I work as an orthopedic sales rep and everything. I mean everything is studied and published in peer reviewed articles. Granted, it's different than brewing, but brewing has been around a lot longer than total joint replacements. Considering Jamil's book was written back in 2010, and Kai came up with a different stir plate model 2 years ago and was presented at last years NHC, it's just funny this stuff is just really being studied.

I'm going to post a link to an article from a PhD that is relative to this topic. Within a week I'll be washing and storing 3 pints of WL810 and pitching one using kai's stirplate math. It makes sense to me and this other article seems to support it. My target is 250 billion and I'll have 4 pints of 275 billion.

I'm debating freezing those with vegetable glycerol since I have a few other batches planned before doing another California Common, or that yeast.. But, I'm confused now based on some of these points. I'm not a microbiologist..

http://www.maltosefalcons.com/tech/yeast-propagation-and-maintenance-principles-and-practices

This girl is a microbiologist and used to teach at UCLA. Her charts seem to support kai's methodology for yeast growth chart, which is linear to a certain point then drops off. Jamil and White's stir plate method is not linear and is the same growth curve as a non aerated starter, with a higher factor. But, Kai and this study seem to contradict that.

I digress, but I often have the same thought that you do. For how long brewing has been around and the fact that there are bachelor's you can get in fermentation sciences, you'd think someone would have nailed this stuff down by now.
 
Nice write-up EAZy. Just food for thought...
I have heard of using BMC (Bud/Miller/Coors) lite products as your wash water in place of boiled water. This eases the process of washing a bit, and has all the benefits of keeping the yeast under beer. Open a glass bottle (or 2) of Miller Lite, flame the opening, dump into bucket/carboy, swirl...&so on. What do you think of this method?

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I think that is an awesome idea to be honest... It's certainly more shelf stable than any homebrew. It's pasteurized after packaging, which is all you are doing by boiling wort anyway, unless you do it under 15 psi. I would even say to use the cheapest stuff you can get, even in a clear bottle. I don't think beer being lighstruck matters for growing yeast, especially if decanting it off.
 
Wow. Interesting read. I stopped washing yeast a while back, but only because of time constraints. This might just bring me back into the habit.
 
Nice write-up EAZy. Just food for thought...
I have heard of using BMC (Bud/Miller/Coors) lite products as your wash water in place of boiled water. This eases the process of washing a bit, and has all the benefits of keeping the yeast under beer. Open a glass bottle (or 2) of Miller Lite, flame the opening, dump into bucket/carboy, swirl...&so on. What do you think of this method?

Sent from my Nexus 7 using Home Brew mobile app

Always the problem remains - the alcohol is not good for the yeast. The idea you suggested made me wonder if de-alcholized beer might work better instead? They are relatively inexpensive, contain wort, and have a minimal alcohol content.
 
With that said, one should always keep in mind that cropping is not an effective way to "bank" cultures. The most foolproof way to maintain a bank of cultures in a home brewery is on solid media in the form of agar slants. Yeast stored on slant can live up to two years without being subcultured onto new blank slants. I kept several difficult to obtain cultures alive for ten years using this method. I would still have those cultures today had I not taken an extended hiatus from the hobby. Anyone who is willing to put forth the effort can learn how to slant yeast and propagate yeast cultures from slants.

EAZ, what is your take on freezing cultures rather than slanting them, in a manner similar to described in this thread? Keeping cultures in small vials in the freezer is more conducive to my circumstances than is messing around with agar agar and such. Just curious what you think of that approach. I've been using it for a couple months with several cultures and so far so good.
 
It is funny. I work as an orthopedic sales rep and everything. I mean everything is studied and published in peer reviewed articles. Granted, it's different than brewing, but brewing has been around a lot longer than total joint replacements. Considering Jamil's book was written back in 2010, and Kai came up with a different stir plate model 2 years ago and was presented at last years NHC, it's just funny this stuff is just really being studied.

Yes, this is funny and we could easily branch off into a more general discussion, but let's take this topic for an example. We are discussing adding no water and storing the harvested yeast with quite a bit of trub under beer versus rinsing with boiled water, both of which are popular with homebrewers. It really wouldn't be that hard for a guy with some fairly simple equipment to find out which culture turns out to be more viable or to have less undesired organisms after various lengths of storage. Maybe Kai will try it soon. Funny thing is, some of the best science of this kind out there is from Kai, at least so far as I've been able to find, but he's got a very small, low budget operation there.

One reason we encounter this kind of situation is that the topic of this thread is of little practical interest to professional breweries. They use their conicals to harvest low-trub yeast samples for reuse and if they get really serious, they can have a serious lab to cultivate pure cultures. Brewing great beer developed slowly over centuries by trial and error. You have beer styles suited to brewing water all over the world without the developers of these styles having any clue about what was actually going on with their local water. So it seems that a purely pragmatic approach is simply a tradition in brewing and there isn't a lot of desire for certainty.

This could seem very strange to me because I'm a math professor. There's a lot of research going on in math, mostly at universities, and almost all of it is purely motivated by curiosity with no practical application in mind. So, why shouldn't interesting questions like this be good topics for biology professors or something? There are a lot of homebrewers out there so I think there is plenty of interest to justify research for curiosity rather than big bucks.
 
Always the problem remains - the alcohol is not good for the yeast. The idea you suggested made me wonder if de-alcholized beer might work better instead? They are relatively inexpensive, contain wort, and have a minimal alcohol content.

Who's saying that the alcohol is not good for the yeast - it stops a lot of other organism from being able to set up shop.
 
i like the idea of keeping it simple which is why the no wash method appeals to me. if i can use a jar of slurry and not have to make a starter, why would i wash yeast to get a smaller amount of yeast? to my mind it's working backwards; wash a bunch of good yeast down the drain then work to build the population back up later.
 
i like the idea of keeping it simple which is why the no wash method appeals to me. if i can use a jar of slurry and not have to make a starter, why would i wash yeast to get a smaller amount of yeast? to my mind it's working backwards; wash a bunch of good yeast down the drain then work to build the population back up later.

But the issue is the dead cells, the protein break material, the hops and the rest of the trub that builds up in time. This is likely not much of an issue during the first collection of slurry, but after collecting it several times in subsequent batches, the dead yeast cells and other trub builds up. You just collect more and more trub each time you pitch and collect, with no removal of any of it each time.
 
Who's saying that the alcohol is not good for the yeast - it stops a lot of other organism from being able to set up shop.

I can't recall where I read that, but I recall reading that alcohol weakens yeast and affects their vitality. This is partly why boiled water is added - to reduce the alcohol concentration.
 
But the issue is the dead cells, the protein break material, the hops and the rest of the trub that builds up in time. This is likely not much of an issue during the first collection of slurry, but after collecting it several times in subsequent batches, the dead yeast cells and other trub builds up. You just collect more and more trub each time you pitch and collect, with no removal of any of it each time.

i don't think that is an issue at all, the amounts are too small and the beer is not adversely affected in any event. have you watched a brewery reuse yeast? they pump it straight from the cone into the next fermentor, no washing. i am totally ready to change my practices and publicly admit i was wrong if i saw any evidence of trub, dead yeast, or break material causing any harmful changes to my beer, but so far i have not. i would love to see any evidence to the contrary, not for the sake of being right or wrong but because it would be very interesting.
 
i don't think that is an issue at all, the amounts are too small and the beer is not adversely affected in any event. have you watched a brewery reuse yeast? they pump it straight from the cone into the next fermentor, no washing. i am totally ready to change my practices and publicly admit i was wrong if i saw any evidence of trub, dead yeast, or break material causing any harmful changes to my beer, but so far i have not. i would love to see any evidence to the contrary, not for the sake of being right or wrong but because it would be very interesting.

But again, the test would have to include repeated use, not just the first collection. For example, if you were to reuse the yeast slurry, say after 7 or 8 times in subsequent brews, one would expect a considerable amount of dead, weak and mutated yeast cells as an accumulation of all those collections. Don't forget that if all the slurry is collected each time, then it would contain almost ALL of the trub associated with every previous slurry. Thus any test should represent repeated use, not just the first slurry.
 
I can't recall where I read that, but I recall reading that alcohol weakens yeast and affects their vitality. This is partly why boiled water is added - to reduce the alcohol concentration.

Here's a Wyeast source that stresses the use of LOW alcohol content:

Keys to Successful Yeast Storage:

Keep the yeast cold, 34°F (1°C).
Store in sterile, vented stainless steel container.
Store under a 3 to 4 inch layer of low alcohol, low hop beer.
Store yeast from only lower alcohol beers.
Minimize trub.
Minimize exposure to oxygen.
Store under a blanket of CO2 with minimal positive pressure.
Use as soon as possible, preferably within 3 to 4 days.
Test for viability, cell count, and contamination prior to pitching.

Source:
http://www.wyeastlab.com/com-yeast-storage.cfm

John
 
I agree with eastoak, there is very little reason to wash yeast, and saving portions of slurry saves a lot of time and effort vs. Washing. That said, there is a good portion of the trub that contains hop material, and bitterness could be carried over to the next batch. I admit it would be minimal, and the yeast itself carries over a small amount of bitterness itself too. If one was to go from a hoppy beer (IPA) to something like a blonde with low bitterness you might consider it, but it would be better to plan your new batches of so you progressively increase in bitterness and alcohol.

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What if you boiled the beer? You would get the benefits of the beer while evaporating some or most of the alcohol off. A 15-minute boil willl leave you with roughly 40% of the original alcohol, so a 5.5 Bud would end up at 2.2

Is that too much? What would be the negatives with this method?
 
But again, the test would have to include repeated use, not just the first collection. For example, if you were to reuse the yeast slurry, say after 7 or 8 times in subsequent brews, one would expect a considerable amount of dead, weak and mutated yeast cells as an accumulation of all those collections. Don't forget that if all the slurry is collected each time, then it would contain almost ALL of the trub associated with every previous slurry. Thus any test should represent repeated use, not just the first slurry.

out of a given yeast cake you are only using a cup, more or less, so you would not have all of the trub. the next cake would give up a cup and so on. i you are pitching the whole cake each time you would have all of the trub but i don't think you are suggesting that.
 
If one was to go from a hoppy beer (IPA) to something like a blonde with low bitterness you might consider it, but it would be better to plan your new batches of so you progressively increase in bitterness and alcohol.

I guess you expressed my concern. I basically only brew lagers, which are very susceptible to off-tastes. So any test should also include light ales and/or lagers.
 
out of a given yeast cake you are only using a cup, more or less, so you would not have all of the trub. the next cake would give up a cup and so on. i you are pitching the whole cake each time you would have all of the trub but i don't think you are suggesting that.

That would be true for ales. But I basically only brew lagers, which require at least two or three times as much slurry. Also, I brew 10 gallons at a time, which means double that amount. So, yes I usually use all of the slurry from a 5 gallon batch (and save the slurry from the other 5 gallon carboy).
 
What if you boiled the beer? You would get the benefits of the beer while evaporating some or most of the alcohol off. A 15-minute boil willl leave you with roughly 40% of the original alcohol, so a 5.5 Bud would end up at 2.2

Is that too much? What would be the negatives with this method?

That sounds reasonable to me.
 
Here's a Wyeast source that stresses the use of LOW alcohol content:

Keys to Successful Yeast Storage:

Keep the yeast cold, 34°F (1°C).
Store in sterile, vented stainless steel container.
Store under a 3 to 4 inch layer of low alcohol, low hop beer.
Store yeast from only lower alcohol beers.
Minimize trub.
Minimize exposure to oxygen.
Store under a blanket of CO2 with minimal positive pressure.
Use as soon as possible, preferably within 3 to 4 days.
Test for viability, cell count, and contamination prior to pitching.

Source:
http://www.wyeastlab.com/com-yeast-storage.cfm

John

But they don't state what "low alcohol" beer is. And i would expect that they are meaning more reusing yeast from a 10% beer is not a great idea, rather than 5% beer. Most yeast is ok up to 9-10% (IIRC) so 5% should be in their comfort zone.
 
That would be true for ales. But I basically only brew lagers, which require at least two or three times as much slurry. Also, I brew 10 gallons at a time, which means double that amount. So, yes I usually use all of the slurry from a 5 gallon batch (and save the slurry from the other 5 gallon carboy).

But what is being suggest is basically taking the same approach as washing the yeast but instead of racking all the beer off the yeast and then adding some water back, the process is to leave some beer in the fermenter and "wash" the yeast with that. You are washing with basically the same amount of liquid, the only difference is one is boiled water adn the other beer.
You could still do the multi satge "washing" if you wish - take the yeast that you get from the intial swirl/sit/decant, let that sit a bit more and then decant into a smaller jar.
As far as the going from least - most flavour beers, this is suggest for washing as well.
And your argument that you need more because you brew 10 gallon batches is not that valid since you will be pitch the greater volume into the larger volume - the ratio will be the same independant of batch size.
 
But what is being suggest is basically taking the same approach as washing the yeast but instead of racking all the beer off the yeast and then adding some water back, the process is to leave some beer in the fermenter and "wash" the yeast with that. You are washing with basically the same amount of liquid, the only difference is one is boiled water adn the other beer.
You could still do the multi satge "washing" if you wish - take the yeast that you get from the intial swirl/sit/decant, let that sit a bit more and then decant into a smaller jar.
As far as the going from least - most flavour beers, this is suggest for washing as well.
And your argument that you need more because you brew 10 gallon batches is not that valid since you will be pitch the greater volume into the larger volume - the ratio will be the same independant of batch size.

Yes, but I was under the assumption that the extra water would dilute the alcohol content, especially if the beer was strong - thus you would save less of the beer in your carboy. But if one is making low alcohol beer (e.g. 5% or less), then I can see using just the beer rather than adding some water.

Regarding my argument re: the 10 gallon batch, perhaps I wasn't very clear. Although I mash and boil ten gallons all at once, I subsequently split it into two separate five-gallon carboys for fermenting and kegging. Thus I use ALL of the slurry from a previous five-gallon carboy and split it between the two five-gallon carboys. I keep the slurry from the other previous five-gallon carboy to split between the two five gallon carboys resulting from my next ten gallon batch.
 
But they don't state what "low alcohol" beer is. And i would expect that they are meaning more reusing yeast from a 10% beer is not a great idea, rather than 5% beer. Most yeast is ok up to 9-10% (IIRC) so 5% should be in their comfort zone.

I agree - that's likely one of the reasons why the proportions of DME and water used in a yeast starter results in a low alcohol starter. The other reason pertains to an optimization of yeast growth and vitality depending on the concentration of yeast in the Erlenmeyer flask.
 
Nice write-up EAZy. Just food for thought...
I have heard of using BMC (Bud/Miller/Coors) lite products as your wash water in place of boiled water. This eases the process of washing a bit, and has all the benefits of keeping the yeast under beer. Open a glass bottle (or 2) of Miller Lite, flame the opening, dump into bucket/carboy, swirl...&so on. What do you think of this method?

Sent from my Nexus 7 using Home Brew mobile app

There a a few cans of BMC Lite sitting in the back of the fridge, hidden by the homebrew that I just can't force myself to drink.

Thanks to you 05m50dan, they now have a purpose in life.

I'll put it to practice this W/E,
'da Kid
 
i don't think that is an issue at all, the amounts are too small and the beer is not adversely affected in any event. have you watched a brewery reuse yeast? they pump it straight from the cone into the next fermentor, no washing. i am totally ready to change my practices and publicly admit i was wrong if i saw any evidence of trub, dead yeast, or break material causing any harmful changes to my beer, but so far i have not. i would love to see any evidence to the contrary, not for the sake of being right or wrong but because it would be very interesting.

They also pull the trub out of the conical early in fermentation. Then they pump the middle yeast slurry for re use. There are still yeast in the fermenting beer. They don't wait for full fermentation and then do it. So, they have less alcohol and no trub in what they pump out. Also, it has been proven that any hops affects yeast reproduction negitavely. Hops are worse than the hot break proteins, and if you get a cold break, that's yeast food.

The idea of NA beer is interesting.. It would be easy to pour one at room temp.. Boiling beer would simply introduce it to more bacteria. If we are talking about sterility, that's just one more step.

The way I'm going, I'm harvesting my yeast off my starters. That's why I got a 5L flask. However, I am inclined to decant the spent wort and use NA beer to wash it and store in the fridge. At least the ph is lower than water and it has no oxygen. Freezing with vegetable glycol has been well established.
 
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