Yeast Harvesting

When I initially started tinkering with the idea of harvesting yeast from starters, I was unable to find references to anyone else using a similar method. Since I wrote about it, I’ve heard from a number of folks who had been using a similar process, hence I take no credit for developing this method and appreciate all the feedback I’ve received.

Matt from wrote a relevant article on Yeast Viability Over Time that seems to suggest yeast retain viability for longer than many of us believe. I strongly recommend you give it and his other great articles a read!

Here is the most updated version of how I harvest yeast from starters.

Make your starter at least 24-36 hours before you plan to pitch, I’ve learned that older strains tend to take a bit more time than more recently harvested yeast, so plan accordingly. Using a good yeast calculator, overbuild your starter by 100 billion cells. BrewUnited’s Overbuild Harvest function makes this so incredibly easy, you can even download a spreadsheet version. Usually, the extra amount will be less than or right about 1 liter.


After at least 24 hours on the stir plate (longer if shaken or using older yeast), you can harvest the yeast. Since I like to crash and decant, I always harvest my yeast the night before I brew. To do this, sanitize an appropriately sized Mason/Ball jar using whatever sanitizer you prefer, remove your flask of starter from the stir plate, secure the stir bar using a magnet, and fill the sanitized jar with the proper amount of slurry. I usually give the flask a good swirl before transferring to ensure homogeneity. Loosely cover the jar with a sanitized lid and place it in the fridge for 24+ hours. This is also the point I’ll move my flask to the cold ferm chamber to crash overnight.


Place the jar in the fridge and pull it out a few hours before you make your next starter. That’s basically it!

Previously, I encouraged people to replace the beer on top of the yeast with pre-boiled and chilled water if they planned to store it for longer than a couple weeks. However, I’ve recently been made aware of some fairly convincing evidence suggesting this is both unnecessary and potentially harmful to the yeast. I started leaving the starter beer on top of the harvested cake and I’ve experienced no noticeably negative impact. For these reasons, I no longer plan to replace the beer with boiled water and recommend others follow suit.

After some time in the fridge, a nice layer of creamy yeast will be sitting at the bottom of the jar.


How many generations of yeast can be harvested before it goes bad?
I’ve only anecdotal evidence, so keep that in mind. At the writing of this article, I have two strains of yeast, WLP090 San Diego Super Yeast and WLP002 English Ale Yeast, both have been harvested 13 times. The 12th beer each fermented tasted great with no noticeable differences compared to the original vial. I’ve used this method successfully with ale, hybrid, and lager strains.

What makes this method any better than rinsing (“washing”) yeast?
To start with, I personally think it is much easier and far less time consuming. Additionally, the yeast fermented a wort of ~1.040 OG that had no hops in it, so it is arguably less stressed and ultimately cleaner. I also like that I’m only harvesting a single jar of yeast as opposed to multiple jars that would eventually end up in the trash.

How much yeast is actually being harvested using this method?
I don’t know. I wish I knew, but I’ve yet to find anyone with the know-how to do an official count. As I mentioned before, I’ve been assuming 100 billion cells, though I fully accept this number is likely way off. Still, it has worked great for me.

If you have any more questions or comments, please do not hesitate to ask. Cheers!

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    1. If your beer is tasting good, who cares what that looks like. That is one of the lessons of this website. Don’t worry about things that don’t matter. Taste the beer!

      1. I think he’s referring to his starter, maybe not. I’m admittedly vain when it comes to my beer, I pine for the crystal clarity expected from the finest commercial ale. But that’s just me, I’m all for people doing what they like!!

      1. I usually know if the starter is a problem when I smell it prior to pitching. Just tossed another bad flask of WLP029 this weekend because it smelled phenolic 🙁

    2. I had that a couple times too. I’m pretty sure that’s burnt DME that didn’t dissolve in the flask. Once I started REALLY making sure the DME was dissolved before I put the flask on the heat, I stopped getting the black stuff.

      1. I’ve been doing this for a few years now and roughly every 6 months I take all my jars out of the fridge, decant off the liquid, then make a large starter with DME and add it to all my jars to regrow all my yeast (I leave then on the counter with loose caps for a few days). Its been working for me so far and Ive never had a strain go bad.

  1. Is there an advantage to overbuilding your starter and harvesting the excess yeast as opposed to just building the original starter with half of the pack and dumping the other half in a sanitized vial?

    1. I have done this twice using 1098 – British Ale with no noticeable negative impact to the lag phase or quality of the finished beer. If I remember correctly, I only had the foil wrapped jar stored in the fridge for 1 month before using it though. So I can’t speak about the shelf life of this practice. I have since switched to storing dry yeast in small sterile vials, wrapping them in foil and storing in the crisper drawer of my fridge. Dry yeast has come a long ways, IMO, and it is far cheaper than smack packs. I recently brewed 2 batches with my vials of Nottingham that had been stored for 11 months. My starter cultures took off in 6-8 hours so I can assume the viability was/is still fairly high given that storage condition. Both beers turned out great. Keep it simple and do whatever works.

  2. If using a full vial of white labs in 1.5L of 1.035 wort, according to the brewunited calc I will have ~262B cells, which is about 100B more than I need. If I save 500ml in a mason jar, is it safe to assume that it would contain 87B cells and that would be enough to make another starter in a few weeks?

    If I split the 500ml in to two jars, would each jar be sufficient to create a starter?

    1. I don’t believe that’s ever been found to be the case, at least not at the rates most home stir plates spin, but truthfully I’m not certain.

      1. So according to this post speed does improve growth:

        I’ve not done this before but just this weekend switched my recipe enough to need a lot less yeast (lower OG), and so improvised and kind of did a reverse of this — pitched 2/3rds of my starter, left the rest, and dumped some starter word on top for another batch this coming weekend. I thought of this post, which was very helpful.

        One thing I’m finding continually challenging the more I read and experiment with starters, though, is the issue of determining your actual cell count. Just the variables in the initial starter: bar speed, temperature, temperature _change_, age of yeast package (and quick tangent here: BF says a 70 day old yeast package is at 50% viability, I emailed WL direct once about an old packet and they told me I had “at least” 50% viability in a 7+ month old packet), any extremes the yeast faced during shipping, ph of starter wort, yeast variety even, other things I’m sure…

        Anyway, part of the fun I guess, but seems like even if you’re just pitching with most of those controlled, you can end up with wildly different yeast counts. My retrospective opinion is that the main advantage is yeast health, and that’s why I continue do it, but man it would be great to know count too!

  3. Just wanted to share my current practice;

    I don’t wash my yeast or pitch onto a cake. Instead, I swirl the cake up, pour directly into sanitized mason jars, and cap until pitch time. I don’t (currently) make starters.

    I forget where I initially read about this, but the post seemed very well informed, and recommended that one mason jar of the trub was roughly the right pitching rate for a medium gravity beer, while two mason jars where the right amount for high gravity beers and lagers (although your recent experiment about lager yeast temperatures has me thinking that by fermenting at higher temps, the need for a larger portion of lager yeast compared to ale yeasts becomes unnecessary).

    I’m on the fourth lager now using this method, but so far I’ve experienced no issues. The article I read (sorry, I can’t seem to find it right now) mentioned that some advocates have gone more than ten generations using the yeast.

    1. I refer to unrinsed yeast stolen from the bottom of a fermentor as “sloppy slurry” and I’ve done a couple xBmts with it… never an issue 🙂

  4. I did my PhD in a yeast lab a long time ago. I’ll take a stab at answering your question about number of cells in your starter when done…
    In the lab, growing yeast in normal lab conditions (rich media, 30degC, shaking at 150 rpm or so), the culture hits stationary phase at somewhere between 10-50 million cells/ml (let’s just say 50 million, but I usually found it to be closer to ten). Assuming that a 1.040 starter, having a higher sugar content than YPD media, can support more cells/ml, but using a stir plate and likely not spinning the fuck out of it and hence not aerating as much maybe works against you, you’re probably hitting around 50-100 million cells/ml i.e. 50-100 billion per liter. I’ve never actually counted cells in wort since I don’t want to contaminate my work stuff with yeast (I’m a neurobiologist now), so really it is all conjecture. There’s got to be at least one homebrewing yeast biologist out there willing to do some counts.
    I think that’s why White Labs does not suggest throwing their vials into a starter… you’re essentially saturating it from the get go. Dumping a vial into a 2L starter maybe doubles your numbers.

    1. The calculators by Jamil Z and Kai T, just to name a few, were done via actually performing step ups, via various methods, and then cell counts.

    I have made every starter i needed for past year with distilled water for 70 cents per gallon from Walmart.Roughly 20 cents a starter for water.

    Two Silver medals and 3 dozen batches have solidified the use(for me) of this easy time saving method,try it!!!

  6. I’m just going to say thank you for this one. I stopped yeast rinsing a long time ago because it’s another item to plan for and it does yield too many jars that end up getting tossed . Since reading that you saved a portion of the starter (besides smacking myself in the head for not thinking of it myself) I’ve saved $50 on yeast in my last 6 batches and can see myself saving hundreds more. So here’s a HUGE thank you for this one.

  7. Hey Marshall! I’ve just recently started overbuilding my yeast starters based on your methods…brilliant idea! So, I’m about to make my next starter with the first harvest…do you use the harvest date as the production date…basically the same as you would do with a new vile of yeast?

      1. Thanks!! This is going to save me $$$ and let me have a sweet yeast collection for different styles!

  8. Lurv the site.
    If one were to use pressured cooked pre-made starters, a la Experimental Brewing, would there be any needed number adjustments when using one of the two Over build calculators recommended on Brulosohpy?

  9. You can store dry yeast in the freezer for even better (~3X) longevity, though fridge temps are good for well over a year with almost no loss.

    Starters? With DRY yeast? Why? Even without buying in bulk (1-2 kg brick), which I assume you are doing (since splitting an 11g sachet even in 1/2 seems ridiculous), building up counts for dry yeast by using a starter and a sachet will cost more in DME (or your time for using grain), risk, time, etc.; than just buying more dry yeast. Buying a bulk brick only makes starters even less economical.

    Also, dry yeast have been specially grown to build up stores of nutrients which prepare them for fermentation- so much so that they don’t even need aeration (if you aren’t going to re-pitch). If you make a starter, you lose most/all of these benefits.

    The current best practice for dry yeast is to rehydrate with boiled/cooled tap water (to 90-100F), and pitch within 30 minutes. Adding nutrients to the water (other than the Go-Ferm fairy dust made specifically for rehydrating), or rehydrating in wort is detrimental to yeast health.

      1. RE: do you have any data on your comment about yeast viability or a reference?

        If I gave you one (or two, or three), would you take that as proof; or would you still require validating it with your own personal research? That’s what I thought.

        These kinds of requests for proof/references are becoming this standard knee-jerk responses to any kind of comment when stating even basic common sense/knowledge. We are not in the middle ages, where you have to wait for journals to be hand transcribed, translated, and carried by camels to you before you can read them.

        I’ll respond with the standard knee-jerk rebuttal to those knee-jerk requests:

        It’s not that complicated. I think dry yeast manufacturers even guarantee 80+% after 1 year of room temp storage, or something like that- and no, I’m not going to provide you any links for that, since I don’t care. I always keep my dry yeast in the fridge/freezer, and use it before 5 years.

  10. RE: storage liquid
    There are some articles out there by a homebrewing microbiologist regarding how to best store yeast slurries. His recommendation was to use an “isotonic solution”. This is simply a saline solution that is similar to the yeast internal fluid. Spent starter, and worse plain water, will exert osmotic pressures, and stress/kill the yeast. It’s fairly simple to do, you just need a good scale, and the proper non-iodized salt (canning/pickling salt works).

    The guy who did the write up was referring to doing this exact type of thing- saving a 100B portion of a yeast starter-, though he personally was only storing tiny (< 10M) samples.

    1. Based on my anecdotal experience, I’m perfectly fine storing yeast under spent starter wort. I’ve prop’d 6+ month old yeast that’s been stored this way and it has worked beautifully.

      1. 1.5 years old yeast from starter has worked for me, but only few cells left so you need to step up starting from small volumes, 100 ml or so

      2. I’ve prop’d 15 month old yeast in a huge 4L starter, no stepping up, and it worked fine.

      3. Yeah, I also did that, and it worked sometimes or not. Depending on the type of beer, if you want to make an IPA this is probably not sufficient, as you would get to few cells. I bought a microscope and tested, and a step up procedure give you the amount of cells needed for a beer. A 1.5 year old starter direct in 4 liter will give you too few cells, but under pitching works ok sometimes, but can give you stressed yeast with undesired flavors, and sometimes to high FG.

      4. Hmm. The beer I made was a 1.070 OG IPA using 15 month old WLP090 I’d previously harvested from a starter.

      5. So you got from 1.5 year old yeast in a 4 liter starter to ferment OG 1.70 down to normal FG 1.012-13?

        I also managed to get there most of the times, but sometimes the beer stopped at too high FG, and I hate too sweet beer. I therefore started the step up procedure, and it has never failed me. Most of the time I count cells also to make shure there is enough.

        I’ve been doing starter saving strategy the last 3-4 years, starting before I read this blog so have some beers from this 🙂 I only buy yeast one time, 10-15 times starter reuse, also store it in glycerol in the freezer, so I could start from scratch

      6. Precisely. In over 500 batches brewed, I’ve had a single beer stall on me, and it was a regular OG Porter that I later realized I used too much Brown Malt in. Besides that, whether under-pitching or not, I get great attenuation. Oh, and I’ve never (ever) used O2 on my beers, regardless of OG.

      7. I was just putting it out there as the preferred way to do it that had been verified by someone who put in the time to figure it out. A simple search should find the guy’s work.

        It’s one of those things that’s so easy (like properly rehydrating dry yeast), that it’s almost a “why not just do it” things. As usual though, someone always responds with the “my way was good enough for my grand pappy, so it’s good enough for me” comment, or, like here, “my beer tastes awesome, explain that”.

        Even more confusing is when a new method involves LESS work, but people still stick to their current method. Not needing to aerate wort for a dry yeast pitch (unless planning to harvest/re-pitch) is one example that comes to mind. Just a case of human nature’s resistance resistance to change, I guess.

    1. For 1 year old yeast, I usually do the first in 100-200 ml starter, chill and then transfer to 1 liter, and then 3-4 liter. I usually start 2-3 weeks before brewing, so there is no stress

      1. how much yeast does that produce on average? what about doing 200 mL, then 1L, then 1L again. Do you have an idea of how much that might produce?

      2. This is not possible to know without a microscope. Sometimes a lot more than needed, sometimes less than I thought. Depending on the number of live cells you start with, and different yeast strains can produce different outcome.

        If not using a microscope, I would overdo it. 100-200 ml, then 1 liter, then 3-4 liter. Then you’re shure to have enough, if you’re not doing a barley wine, or RIS or similar.

      3. Somebody, I think it was Braukaiser, did some work on stepping and yeast counts. The gist was that stepping wasn’t necessary for homebrewing ranges (up to 8X or something), and the primary determinant for ending cell count was the size of the starter (+ the original cell count, of course, which was otherwise irrelevant). I’m not talking about starting from slants/plates; but even then, I think the main reason for small initial steps when doing that is for contamination issues (trying to get a healthy number of bugs to assure a reasonably pure culture), not because stepping causes some magic to happen with the yeast itself.

        The pro labs step up by even greater multiples than that. They also continuously aerate, which I do as well, and might be one reason why stepping might help using the standard homebrew method. Personally, I use an aquarium pump and a piece of hose (no stone, and which I throttle) at the bottom of the flask. It’s akin to an airlock (of which I use one on the output). I’ve gotten much greater growth, as verified by scientifically eyeballing the yeast layer with a precise amount of squint and sideways glance. I can provide the data, accurate to ~1/8 inch, if anyone needs it for replicating and verifying the method.

        Think about it- once you start to get some activity/krausen, there isn’t much O2 getting to your bugs, and therefore, no more growth- just beer. My starter liquid tasted much different, as well, and not like a crappy beer when I do it the normal way.

  11. Yeah, I would like to err on the side of more. Thanks for the info. Could this same propagation be used for a tiny amount of cells, like from 2 or 3 year old vial of White Labs? Is there a cutoff point?!

  12. Bo, if yeast is only 2-3 months old I just toss it in a 4 liter starter. When talking about stepping up, I mean really old yeast 6 months to 2 years

    1. RE: stepping yeast

      I believe the motivation for stepping yeast (at the pro/lab level) is almost solely done for purity of the culture, not by any growth limitation of the yeast. They still do huge steps. At the home level, stepping from a plate/slant/very old slurry into a small (100ml?) starter is probably wise idea, for the same reasons. However, doing multiple steps (less than say 8X) because it has previously resulted in more cells, is likely do to flaw in the process- like lack of O2 availability, even though it’s on a stir plate.

      This is why I do continuous aeration on the stir plate. It counteracts the CO2 blanket, as well as reducing krausen/blow-off. It’s trivial to make, and is the same design as a jar-based airlock, plus a filter. There is an added benefit of less chance of contamination, which was what finally motivated me- Yeast don’t have legs, but fruit flies do. I had one climb past my foil cap, and into a 3+ liter starter.

      RE: using 2 year old yeast

      I’m not sure what the cell counts are in a slurry that old, since all the calc tools say “0%” after only ~3 months, but there still isn’t a need for multiple steps. One small step to verify purity/vitality- if only by smell/look/taste- then into whatever size starter will get your desired count. If growth has historically been better using multiple steps, it’s likely due to a flaw in the process being used. Using the standard 10P starter (with nutrients) and access to O2, growth is linear according to starter volume. Unless continuous starter infusion is used to maintain low sugar levels, CO2 and alcohol will inevitably be made, along with some new yeast; but without counteracting the CO2 blanket, you’ll only make beer, and no significant yeast growth.

      Also, using 2 year old yeast is just one more reason to store under an isotonic solution. It’s very easy/cheap, and results in both more and healthier yeast, especially after extended storage. I doubt anyone plans on storing a portion of a starter for 2 years, or even 6 months; but plans change, and things happen. Doing cryo/glycol for long term storage is more than most want to tackle, but nuking some saline for ~1 minute is minimal amount of added effort for some huge benefits- like if the brew you planned for next month gets postponed by a couple of years.

      1. I have a microscope, and stepping up really improve total cell numbers in the final starter. You don’t step up for purity. When pro starting a new culture, they go to glycerol stock in -80C freezer and start from there, never from a starter or brew, because chance of genetic drift during growth. Then they have to step up, because touching a sterile needle in the yeast stock, and then inoculating a 4 liter starter is not a good solution.

        I am a microbiologist and molecular biologist, and work with fungi, so I have a lot of experience growing microbes.

        But you need to be careful, because steppimg up increase chance of contamination

      2. Can the discussion stay on topic- which is about “homebrew” level yeast storage/saving?
        Your responses only seems to be serving as a source of obfuscation by dragging in irrelevant topics, and focusing on impertinent issues.

        RE: “I have a microscope, and stepping up really improve total cell numbers in the final starter.”

        There is no requirement regarding stepping yeast, based on science, that supports your statement- whether you’re watching over them with a microscope, or, even worse, threatening them with it unless they bend to your will. As long as basic growth conditions are met, stepping provides no benefit of increased counts.

        As I mentioned previously, if better growth results are seen by “stepping multiple times”, especially for less the less than 10X growth using typical homebrew gear, the likely cause is insufficient O2. There are many professional papers on this, as well as a bunch of homebrewers reinventing the wheel with their own experimental “revelations” that verify this. It’s not a difficult concept, or even counter-intuitive.

        A 10P starter is mainly making beer- alcohols and CO2. This activity easily overcomes the gas exchange capacities to keep O2 available in the solution/interface of the typical homebrewer’s stir plate and flask . There is lots of stuff out there on this, and it’s not a difficult concept to grasp.

        Simply measuring and documenting your process, regardless of the thoroughness and/or the level of magnification, does not validate it, especially when it contradicts prevailing knowledge.

        What gear/process are you using?

        If you aren’t using continuous air injection, or haven’t at least conducted a test for comparison, I don’t see what value you add by stating that you, personally, have “documented by microscopy” better growth by multi-stepping; especially when stated as a rebuttal to well understood/accepted practices that multiple smaller “steps”, in general, do not enhance cell count vs. an equivalent single step- as long as growth conditions are met, of course.

      3. RE: “You don’t step up for purity.”

        It’s apparent in my responses that I only referenced “stepping being done for purity” in regards to an initial “step” starting with plates/slants. This is exactly why this initial prop is done when tiny numbers of starting cells are involved- because it’s much easier to maintain sanitary/sterile conditions for a smaller volume, therefore overwhelming any contamination and maintaining “purity”. Once the yeast cell count can easily overcome any normal/expected contamination level for a subsequent step, there is no need, or benefit, from further intermediate steps.

        All of that is largely irrelevant, since most homebrewers don’t want to bother with glycerin/cryo storage, and it certainly isn’t the topic of this article. Stepping from banked cultures also introduces a whole bunch of other issues, as well, like yeast behavior, which is a whole other topic. The discussion here is about storing huge numbers of yeast in mason jars in in the family fridge- right between little Bobby’s juice boxes and granddad’s suppositories .

        As I also commented previously, your 100ml of 2 year old slurry probably falls in this “small cell count” category, and would benefit from an initial small prop, if for nothing else than to verify viability/behavior before wasting 4L of wort and a day’s time.

        The stepping I’m mainly talking about is the typical “stepping” done in the homebrew realm- something like ~100B in a 1 liter, then a 2l, then a 4l. There is no basis for this resulting in greater final counts, unless the process is preventing access to O2. The growth/final cell count is limited (mainly) by available food and O2, regardless of the initial cell count.

      4. RE: “When pro starting a new culture, they go to glycerol stock in -80C freezer and start from there,”

        I think we’re all aware that “pros” occasionally start from banked, pure cultures. Similarly, we brewers (home and commercial) occasionally get a fresh batch from the “pros” (our bank).

        I already said as much, and also that (most) homebrewers do not want the hassle (yourself included, it seems, since you preferred to use 100ml of 2 year old slurry) of dealing with cryo storage, and even worse, the retrieval/culturing.

        RE: “never from a starter or brew, because chance of genetic drift during growth.”

        Growth isn’t the major source of drift- especially the kind of drift brewers are worried about-, fermentation cycles are; and that’s exactly what’s happening during each “step” of a 10P starter. Therefore, wouldn’t minimizing steps be preferred if minimizing drift is desired? (It’s not really a question, BTW.)

        The “pros” use continous injection of feedstock (and O2) to maintain optimal (low) sugar concentrations, which induces maximum growth (only). There is minimal fermentation, so therefore almost no genetic drift, either. A typical 10P homebrew starter is many multiples (50X?) of the max concentration for “growth only” (as compared to growth only conditions), and is mainly making CO2 and alcohols (beer), even when provided with access to unlimited O2.

        I’m sure that, as a microbiologist, you’re aware of the two different metabolic pathways in play here. I chose to leave them out, because a bunch of jargon isn’t needed, or beneficial, to the discussion.

      5. RE: “touching a sterile needle in the yeast stock, and then inoculating a 4 liter starter is not a good solution”

        The “pros” certainly do the equivalent of a “needle dab” in a 4L starter as a standard procedure, only on a much larger scale. Like when propping up a 20K+ L batch for spray drying. Or at least they used to. There is probably some “continuous” process out there now, too.

        There is a danger of starting with a small “absolute” (vs. relative) number of cells, and that is an unwanted change in behaviors (floc, esters, attenuation, etc.) resulting from an anomaly in the small sample size. The “pros” have procedures/practices in place to either prevent and/or verify the absence of this. This is yet more additional work a homebrewer “should” add to the cryo storage process, but rarely do. Most homebrewers will gladly pay ~$8 for a new, vetted culture vs. all the hassle of storing/propping/verifying a cryo sample. Storing a 100B portion of a starter, which is the topic of this article, is many orders simpler of a task; eliminates almost all of the concerns you mentioned; and is well worth the hassle for many homebrewers.

        Again, this has little to do with enhancing cell growth, which is the stance you continue to defend as your rationale for carrying out multiple steps vs. a single large one. There are cases where multiple steps vs. an equivalent single one can be beneficial, but enhanced growth is not one of them. Maybe it’s time to put your fancy equipment and book learning to some use, and verify that you aren’t depriving your starters of O2.

      6. I have tossed a 1 year starter into 4 liter new starter and the final beer did not ferment well, stopping at to high FG. I have also made a step up starter 3 times from 1 year starter, and this fermented the beer to the correct FG. Both beers where similar OG, and I see the ending step up starter has far more cells per ml in the microscope than the one without step up, explaining the differences. Using a stirrer, nothing else.

        I know what I will use… Doesn’t matter what Google says, a lot of personal opinions out there. Even if people put there opinions on web doesn’t mean they are correct. Real microscope measurements are difficult to argue with.

      7. “Doesn’t matter what Google says, a lot of personal opinions out there. Even if people put there opinions on web doesn’t mean they are correct”

        Exactly, which applies equally to yours, as well. Even more so than mine. At least I have continually downplayed my own anecdotal experiences, as well as referencing that my “opinion” is based on methods/results from well accepted/verified studies and commercial production practices- which are all easily found, albeit by resorting to the internet, and possibly even Google, for sources. I’m sure you would still classify all of these vetted and verified studies as “internet opinions” (which they are, just generally accepted and proven ones), since they disagree with your own personal assumptions and experience.

        At least I gave some actual logic/reasoning/basis for my methods/opinions, which could be challenged. You, on the other hand, resorted to three classic “Red Herring” fallacies of logic:

        Argument from Authority/Appeal to Accomplishment- stating lofty credentials (and a microscope) as proof that your opinion is correct, merely because you, the expert, says it is. (Not to mention the whole purity/needle inoculation sidetrack) Is there no other basis for your opinion (besides your low value, anecdotal “data”)?

        Appeal to Consequences- saying my method is wrong, not because it doesn’t work, but because it may result in genetic drift (which in actuality only makes your own argument weaker, since it’s your method that is more likely to increase drift)

        Straw Man- insinuating my stance cannot be valid because the internet is full of nothing but bogus, personal, unsupported opinions, and so anything found there proves nothing. Therefore, your own personal, unsupported opinion is as valid (or moreso because of your impeccable pedigree) as anything to the contrary found anywhere on the internet.

        “Real microscope measurements are difficult to argue with.”
        It’s comical that you’re still waving your fancy microscope around as somehow being proof positive, when it’s obvious your methods/reasoning are completely flawed. Regardless of how accurate your cell count data is, it doesn’t explain WHY stepping worked for you, or refute my claim (which you deny) that continuous aeration works better than multiple steps, and is the basis/root cause of why stepping worked for you better than a single, non-aerated step.

        Claiming that the color the shirt you were wearing was the causal factor makes just as much sense, though I prefer to go with my old standby of swinging a dead chicken over my head when I want to ensure things turn out OK.

        There’s a reason why “lab techs” are just trained monkeys, and don’t author papers. Counting cells doesn’t provide any insight. It’s only data that still needs to be turned into information by someone willing to put some actual thought into the matter.

        Have you never bothered to think about WHY you might have gotten more cells by stepping? Isn’t finding out the “why” what you “scientists” are supposed to do? Your (single) negative experience could have even been due to starting with a completely different culture, since it seems you never bothered to verify your theory with a split test. It’s much more likely that it’s still just a lack of O2 when not stepping, and slightly more O2 when stepping, since you are only using a simple stir plate (which, in a real lab, isn’t even typically used for yeast, because of the O2 issue); but it seems you will never pull your head out of the sand to consider that as a possible cause.

      8. Just so I have this straight-
        You, the multi-papered microbiologist, molecular biologist, and microscope possessing, professional fungi lab rat, are going to base everything you do, forever, solely off of the personal, anecdotal results of one failed ferment when using a non-stepped, non-aerated pitch?

        You aren’t even going to try to reason out WHY this might have happened, much less do a repeat/verification test by splitting a sample for each method?

        Ideally, you would split the sample three ways, and add continuous O2 to one. I’m not holding out much hope for that, though, since you continually refuse to consider even the remotest possibility that the cause could be a lack of O2, and simply keep restating that “my beer tastes awesome when I step, so there”.

        I believe I’ve stated, several times, the likely reason for your lower than desired cell counts when not stepping- lack of O2. You have given no valid reasoning to support your opinion for why stepping works (for you), or even to discredit continuous aeration as a viable method (again, they are related). It should be a trivial exercise to test continuous aeration, given your impeccable scholastic credentials and superior equipment (which you continually/confusingly offer as proof you’re right). Alas, it’s like trying to convince someone from the dark ages that no matter how many times flies “magically” emerge from a rotting piece of meat, they are not spontaneously generated from the aether. I’m scared to even think about what your stance on climate change or vaccines might be.

        I will admit, though, that you’ve single handedly restored my faith in science. Without dedicated scientists, like yourself, blindly clinging to indefensible, deeply held personal beliefs, and defiantly keeping your mind closed to new ideas, society would have long ago succumbed to the radical, new age ideas promoted by organized religions- a round earth orbiting the sun; dolphins (which are obviously a fish, and always have been) having once lived on land; the Grand Canyon being older than 5000 years; humans evolving from monkeys; lightning being simply an electrical discharge and not Thor threatening us with his hammer- the consequences are endless.

        I can only hope that you aren’t in charge of designing your own experimental studies.

        If anybody else is (still) reading this, I will again advise that you not to take my word for it. There is plenty of information out there from reputable sources about the issues with CO2 blanketing and benefits of continuous aeration. A stone isn’t even needed, and usually just causes issues. More growth, healthier yeast, less krausen/blow off, less head space needed, no worries about fruit flies crawling in- what’s not to like?

  13. I’ve been using this method for about 6 batches now and had a question about the harvested yeast. You mention putting the jar of yeast in the fridge covered with a loose lid for 24+ hours. After that, do you tighten the lid and store? I guess my concern would be that there is still fermentable sugar in the beer and (as I’ve had happen already), pressure might build up in the jars to a dangerous level.

    My thought is that chilling an unfinished starter might just suspend the fermentation and could lead to dangerous conditions. Do you do anything to mitigate this?

  14. Very interested in giving this method a try… Just curious–do you sanitize/sterilize the mouth of your flask before you pour the excess slurry into your jar? I guess I was wondering if you were concerned about pulling anything into the flask when you tip it back up after pouring? Thanks!

      1. OK. The question that would’ve made more sense is what about the jar of yeast–after it’s been in the fridge for a while (weeks/months), do you do anything to sanitize the rim before you pour it into your new starter?

  15. The responses you’re getting are typical when coming from experienced (and knowledgeable) homebrewers. Contrary to advice given to beginners, there are many times when sanitation can be lax, as long as the repercussions are well known- like in this case when the numbers of known good cells will typically overwhelm any contamination, especially when weighed against plans for the sample (short vs. long term storage, small vs. large sample, etc.). For instance, if you keg, sanitation at all stages can be very lax since the beer is stored cold, and usually gone before any contamination takes hold. Bottling and/or aging is different game.

    If I’ve got a bottle of star-san handy, I’ll usually remove the band, and spray the lid/jar area, but one could argue that it could also mobilize/suspend any contamination residing there, and facilitate transfer. When I’ve forgotten to take my meds, I’ve felt compelled to do 2 rounds of this when doing long term storage/retrieval.

  16. Awesome advice! Looking forward to having my own little yeast storage in the basement! One question came up in my mind: to be able to pour the whole yeast cake out from the jar – do you empty the old beer on top of it first and then pour in some of the new starter wort – swirl and pitch in the flask? Or do you swirl and pitch the whole content of the jar, including the old starter wort?

    Thanks for your work, man!

  17. I really like this method, but one fact about this method is still unclear to me. When I use my saved yeast and make a new starter on it for next brewday. What date is used in the yeastcalculator this time? Do I use the date I did put it in the jar and put it in fridge? Am i thinking right ?

    1. I don’t sterilize my mason jars, I clean them with hot water and dish soap then sanitize them with Iodophor (of late) and/or StarSan.

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