For the last two plus years I have been simply re-pitching unwashed harvested slurry batch to batch similar to how a commercial brewery would harvest and repitch. I realize this is not a revolutionary technique, there are plenty of homebrewers who do this as well, but it's a technique I think that is being overlooked by a lot of homebrewers. It's a very simple process and actually has helped improve my beers and my knowledge of how a yeast pitch can evolve from generation to generation. Before I get into this keep in mind that I am not a microbiologist, so there may be some things that folks disagree with here but this practice has been tried and true over 40+ batches of my own beer, as well as in a commercial setting.
A look down the carboy neck at some fairly clean slurry. |
With those two points in mind all the only equipment you really need is a vessel to store your slurry in. Mason jars work fine but I opt for something more fit for yeast storage in these Media Bottles or Polypropylene Jars. I like the media bottles best because both the lid and bottle are autoclavable, with the lid being polypropylene and the borosilicate glass container, so I can ensure the thing is super sterile by boiling or better yet using the pressure cooker. Not to mention this is a lab grade product and should last forever, assuming you don't drop it! The Polypropylene jars are great as well but I notice the rubber gasket can get gunked up over time, I tend to use those more for storing strains of Brettanomyces and mixed cultures where they spend more time in the jar being fed and will reside in for long stretches.
This was, believe it or not, a pretty hoppy beer. Look how "clean" the slurry is. |
The Alcohol lamp is there, i swear. |
Once settled this was about 800ml of dense slurry. |
There is absolutely a benefit (see answer at the top of the thread):I already had this post mostly finished when I saw Neva say this and I am glad I waited to post it because this is useful information from someone smarter than I. Her point about the 2nd or 3rd generations being the most optimal is totally in line with my experience, but I would have said generation 4 was the sweet spot. It's nice to have some reassurance from a leader in the industry.
In general, yeast from a lab takes 2-3 generations before they are optimal condition for actual fermentations, so if yeast can be harvested well, you'll get some great yeast out of it.
It can take a few turns for the yeast to be completely acclimated to the fermentation environment, but once they are, performance is optimal around generation 3.
With a starter, its not that you're necessarily losing these benefits. While the yeast is not getting used to environments without oxygen (fermentation), you're still building up yeast metabolism and yeast activity so you'll get a faster, stronger start with a shorter lag.
Call me a romantic but I love seeing how the culture performs as those generations pass, sometimes the changes are good but there is a point of diminishing returns. You'll know when that time comes, it's been more of a gradual shift than an abrupt one for me. If you notice off-flavors (fusel alcohols, acetaldehyde, diacetyl etc) or under attenuation you should dump and get a new pitch. In the case of the 8 generation Wallonian pitch I had recently, I would have pitched it further but it got older than I wanted and decided to add it to a mixed culture that needed some extra Saccharomyces help. I think Wallonian was released in early 2014, and I've only bought two pitches in that time. With it being a Saison strain I'm not as afraid of some contaminations of LAB, Brett, or wild yeast as I would be my preferred hoppy beer strain Wyeast 1318.
As with any home yeast procedures it's inevitable that you will get some sort of contamination in your slurry, per Jamil Zainasheff on the Brewing Network most professional breweries do! There are some more advanced techniques including acid washing to clean up your culture if you want to go that route, I don't however I may try it just for the learning experience. Normally after 4-8 generations I am fine spending another $7-10 for a new pitch. I know it might seem a bit scary to do this, but give it a try at least once and see how you make out. One things for sure, you'll see active fermentation as fast as you've ever seen.
I like this technique. I typically do a starter and then just keep back a portion of the clean started to build up and pitch again. With my last round of ECY-08 I've done your technique and my starter one. So I'll have plenty of yeast to use for a while. I really like how that one turned out. I plan on using it to brew another batch of Kathleen as well as a Grisette.
ReplyDeleteI need to get some of those nifty bottles you have to store my slurry. I also need to get an alcohol lamp. I love that this hobby has so many different avenues to explore.
I do the large starter and hold back method and have pretty much been doing that for 2+ years. With this method I've pretty much been able to keep a single strain indefinitely. My house saison cocktail is roughly a year old and I only use it every 2 months or so. It's good because it yields consistent results, but as you said, that's also a negative because the strain never fully adapts to your process. As a fellow 1318 user over the past 2 or so years (other than the occasional affair with Conan), how do you see that strain drift over time (ie. attenuation, ester production, flocculation, etc.)?
ReplyDeleteI have not seen much drift when using 1318, but I have never gone of 6 generations with the strain due to a few factors each time, my last culture produced a pellicle despite tasting great. I hope to take it much further down the generation line with a current culture I have going now, I am at gen 4.
DeleteI think the value in this process for me is I can do the big starter at the beginning, keep a clean non house version, feed it once in a while, and the repitch the house broken slurry, the best of both worlds. I'm not going to lie, I do this w/out the autoclaved jars (just boiled), and the alcohol burner, because it's the easisest method I've determined that produces good results, but I have not compared doing a fresh vs slurry batch to validate the results, but I've have not had any contamination issues.
ReplyDeleteDo you use a funnel or something to help with transferring your slurry? I prob would make a mess!
ReplyDeleteNope, thats more to clean and sanitize and I am trying to reduce the chances of wild yeast/bacteria. Its not too difficult to slowly pour into these vessels.
DeleteGreat stuff, Ed! Do you see a lot of stratification in the jar as it sits refrigerated? If so, do you try to leave out the bottom layer of your pitches?
ReplyDeleteIt depends on the beer I am harvesting from but for the most part no I dont see a ton of stratification. I attribute this to my whirlpool and stainless hop spider keeping things relatively clear going into the FV. I will post a photo of a well settled DuPont culture (from a Saison) and a newly harvested 1318 culture (heavily hopped Pale Ale) so folks can see how clean these cultures are.
DeleteEd,
ReplyDeleteCan I boil the the Media Bottles and the cap from those Polypropylene Jars in order to sterilize them?
You can boil the ones I linked in the post, cap and all.
DeleteSorry for the dumb q, but how do you store the starter (yeast slurry + wort) and for how long, before you pitch it?
ReplyDeleteI store it in the media bottles in the photo above, which are filled right from the fermenter. I try to use that slurry within 2 months, normally much sooner. Depending on how old the slurry is I may or may not wake it up in a starter.
DeleteDo you experience issues with fruit flies when repitching? Because you're going to get fruit flies, right? Have you ever tried using a fake starter? Maybe it's a porter? XOXO, MJ
ReplyDeleteDo you dry hop in a bag or some other method of removing hop matter when collecting slurry from your hoppy beers?
ReplyDeleteI dry hop in the keg with a nylon bag suspended, normally I will then closed transfer the beer off the dry hops to the serving keg but sometimes Ill just yank the bag. So the yeast is harvest before the dry hops even go in.
DeleteWhich pressure cooker do you use?
ReplyDeleteNothing terribly special.
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Do you cold crash your beers prior to harvesting? If not, are you at all concerned about selectively grabbing the more flocculant cells?
ReplyDeleteI do cold crash yes, I probably should have mentioned that. Im not totally sure though that after 2-3 weeks in primary that I wouldnt be fine harvesting, but I do worry about that yea.
DeleteI do cold crash yes, I probably should have mentioned that. Im not totally sure though that after 2-3 weeks in primary that I wouldnt be fine harvesting, but I do worry about that yea.
DeleteThanks for getting back to me. Due to restraints (small apartment, one mini fridge to ferment) I never cold crash my beers. I do, however, leave the beer in the primary fermenter for on the order of 2 to 3 weeks. I'm currently practicing your harvesting method and have had success, but I've only re-used the yeast once or twice. I'll report back if I see any issues in future generations while continuing to neglect the cold crash.
DeleteCan I just say what a relief to find someone who actually knows what theyre talking about on the internet. You definitely know how to bring an issue to light and make it important. More people need to read this and understand this side of the story. I cant believe youre not more popular because you definitely have the gift.
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I'd have to check with you here. Which is not something I usually do! I enjoy reading a post that will make people think. Also, thanks for allowing me to comment!
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