Author Topic: A bunch of questions on harvesting yeast  (Read 791 times)

Offline Joe_Beer

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Re: A bunch of questions on harvesting yeast
« Reply #15 on: October 14, 2020, 09:59:30 PM »
Thanks - you guys just made this way easier :J

Offline Joe_Beer

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Re: A bunch of questions on harvesting yeast
« Reply #16 on: November 08, 2020, 01:01:14 AM »
So I had these three jars sitting in the back of my kegerator and a couple days ago the temp controller blinked out and it got below freezing. I noticed some slushy looking ice at the tops of the jars. The yeast at the bottom didn't seem to be frozen though. I was going to use this stuff tomorrow so thought I'd better put it in a starter to see what happens (never did this before). Boiled 1000ml of water, threw in a cup of DME and then let it cool. Poured off most of the beer in the yeast jar and then dumped the whole jar in along with 1/2 tsp of yeast nutrient.  The starter wort was 1.045 when I dumped the yeast in. It's been going for about 10 hours around 72F ambient. There is mild activity in the airloc. How do I know if this is viable and worth pitching into a batch? Also, do I pitch the whole 1000ml of starter or should I let it settle and pour off what I can and only pitch the slurry?

Offline HopDen

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Re: A bunch of questions on harvesting yeast
« Reply #17 on: November 08, 2020, 01:02:49 PM »
So I had these three jars sitting in the back of my kegerator and a couple days ago the temp controller blinked out and it got below freezing. I noticed some slushy looking ice at the tops of the jars. The yeast at the bottom didn't seem to be frozen though. I was going to use this stuff tomorrow so thought I'd better put it in a starter to see what happens (never did this before). Boiled 1000ml of water, threw in a cup of DME and then let it cool. Poured off most of the beer in the yeast jar and then dumped the whole jar in along with 1/2 tsp of yeast nutrient.  The starter wort was 1.045 when I dumped the yeast in. It's been going for about 10 hours around 72F ambient. There is mild activity in the airloc. How do I know if this is viable and worth pitching into a batch? Also, do I pitch the whole 1000ml of starter or should I let it settle and pour off what I can and only pitch the slurry?


If you are concerned about over-pitching, use a yeast calculator. If I were brewing, I would use all of it. If you're worried about the yeast viability, have a backup yeast if your starter doesn't kick in. I think it will work though.

Keep us posted!!

Offline Saccharomyces

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Re: A bunch of questions on harvesting yeast
« Reply #18 on: November 08, 2020, 02:32:11 PM »
How do I know if this is viable and worth pitching into a batch? Also, do I pitch the whole 1000ml of starter or should I let it settle and pour off what I can and only pitch the slurry?

First off, if you ever find yourself in this situation in the future, resist the urge to dump everything into 1L of starter.   If you have a scale that can measure in grams, make starters based on the metric system (you will thank me later).   When attempting to revive stressed yeast cells, it is better to start with a 5% weight by volume (w/v) wort solution (5 degrees Plato or an S.G. of 1.020), which is 50 grams of dry malt extract dissolved into a 1L solution.  With normal starters, you want a 10% w/v solution (10 degrees Plato or an S.G. of 1.040), which is 100 grams of dry malt extract dissolved into a 1L solution.  It is best not to mix metric and U.S. standard units of measure when working with yeast cultures.  The reason being that one U.S. fluid ounce weighs more than one U.S. dry ounce and a liter is larger than a quart.  If using U.S. standard units of measure, the weight of dry malt extract in a 10% v/w solution is equal to the starter volume in fluid ounces * 0.106.  With the metric system, one milliliter of water weighs 1 gram, which drastically simplifies w/v calculations because all calculations are base 10.

That being said, I would give the culture more time to start and then decant about 100ml of the liquid fraction into new starter wort.  That will leave behind of all of the break and dead cells, which will probably be massive if ice crystals formed in the crops.  Freezing yeast cells without a cryoprotectant can cause the fluid inside of the cells to freeze and burst cell walls.  If any cells survived the ordeal, they had strong cell walls that have more than likely have undergone significant stress.  It is worth attempting to revive the culture because the cells that are left are hardcore. 


Offline Joe_Beer

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Re: A bunch of questions on harvesting yeast
« Reply #19 on: November 09, 2020, 12:20:19 PM »
If you are concerned about over-pitching, use a yeast calculator. If I were brewing, I would use all of it. If you're worried about the yeast viability, have a backup yeast if your starter doesn't kick in. I think it will work though.

Keep us posted!!

Used all of it and managed to get to the LHBS to pick up a new pack of Lutra just in case. Don't think I'll need it though. I need a bigger blowoff! =D
https://imgur.com/a/BT1imIR

If you can't load the link, it's a gif of what I woke up to this morning. I re-pitched the 1 liter starter and this is the action 10 hours later at 72F.  The 1/2" blowoff is getting plugged and kind of releasing in an erupting fashion. I've pushed down on the lid a few times to help clear it and it's finally perking steadily now but I really need to get a bigger blowoff for this Kveik. It's not like the US-05 I've been using all summer.

Next time I make a starter, I'll work through the very thorough and helpful info left by Saccharomyces. I made the starter in a 1 gallon cider jug and couldn't decant it very easily without disturbing the bottom layers. I tried chilling it for a couple hours and it did stratify nicely and settle out but the jug just mixed it all up again when trying to pour it.  Maybe I'll invest in one of those beakers next time. Any recommendations? Preferably with a stopper size for an airloc?



Offline goose

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Re: A bunch of questions on harvesting yeast
« Reply #20 on: November 09, 2020, 02:16:50 PM »
Do an experiment and proceed with 2 of them as you wish but on the 3rd do as I suggest and see if you can tell any difference.

Sounds like a plan but isn't that bottom layer dead yeast? I thought the usable stuff stuff was supposed to materialize in the layer above that to get poured off. Maybe I'm all confused.

I just pitch it all.  Works great and less chance of screwing something up.

^^^^This.
I use the same rationale when I re-pitch a slurry.  As Denny says, less room for error and I don't taste any rubberiness from autolysis.
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Offline Joe_Beer

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Re: A bunch of questions on harvesting yeast
« Reply #21 on: November 14, 2020, 12:07:37 PM »
So the kveik looks like it's almost done. Gravity has dropped about .1 brix/day for the past three days. It looks like it's going to finish right around 10 brix. The last batch with this same yeast finished at 8 brix. My OG was only .5 brix higher on this batch so thought it would finish at 8.5 or close to it. Is finishing higher typical of re-pitched yeast?

Offline Saccharomyces

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Re: A bunch of questions on harvesting yeast
« Reply #22 on: November 14, 2020, 04:28:27 PM »
So the kveik looks like it's almost done. Gravity has dropped about .1 brix/day for the past three days. It looks like it's going to finish right around 10 brix. The last batch with this same yeast finished at 8 brix. My OG was only .5 brix higher on this batch so thought it would finish at 8.5 or close to it. Is finishing higher typical of re-pitched yeast?

Were you a wine maker before you start to brew?  The reason I ask is that Brix is the scale that wine makers use.  Brewers use Specific Gravity or Degrees Plato.  Degrees Plato and Brix are basically the same thing when the solvent is water.

Offline Joe_Beer

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Re: A bunch of questions on harvesting yeast
« Reply #23 on: November 14, 2020, 06:04:08 PM »
Were you a wine maker before you start to brew?

Not a winemaker. I use a refractometer for measuring gravity since it only needs a small amout of wort. Someone told me not to use the SG scale on it as it wasn't accurate. Not sure if they were talking about a specific manufacturer or what. I've checked my refractometer over it's range against a converter (https://www.brewersfriend.com/refractometer-calculator/) and it seems to be spot on (Brix <> SG @1.0 ) so not sure what the issue actually is.
« Last Edit: November 14, 2020, 06:10:55 PM by Joe_Beer »

Offline Saccharomyces

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Re: A bunch of questions on harvesting yeast
« Reply #24 on: November 15, 2020, 02:01:36 PM »
What if I told you, I only take original and terminal gravity readings and that is only for quality control reasons?   A yeast culture will tell you when it is finished fermenting. if you are using an airlock and the temperature of the green beer is not rising (hence, allowing CO2 gas to come out of solution), airlock activity will slow to a crawl, eventually stop and the green beer will start to clear.  Far too many amateur brewers have adopted crash cooling in order to get a culture to drop out of suspension.  Crash cooling may be necessary for professional brewers in order to meet production schedule demands, but it is absolutely an unnecessary step for amateur brewers.  The culture will floc and drop clear when it is done.  Some powdery (i.e., low to non-flocculating) strains take longer to drop than others, but they will drop if given enough time.  If a culture is in suspension, it still has work to do; therefore, patience is a virtue.

Offline Saccharomyces

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Re: A bunch of questions on harvesting yeast
« Reply #25 on: November 15, 2020, 02:09:04 PM »
By the way, anyone with a pulse has heard AB's claim that Bud is beechwood aged.  However, in this case the beechwood adds no flavor because the aging process is based on the old practice of using beechwood to clarify beer.  The aging tank  (a.k.a. chip cask) is filled with boiled beechwood chips. The purpose of the chips is to increase the surface area on which AB's yeast culture can settle.  That is their sole purpose.

Offline Joe_Beer

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Re: A bunch of questions on harvesting yeast
« Reply #26 on: November 15, 2020, 02:41:42 PM »
Man, you really have your info nailed down. Yep, I've heard the AB claim but honestly never gave it much thought..heh.. One of those beer commercials used to make a big deal out of "krausening" or claimed their beer was "krausen'd" as well :o

As far as CO2 coming out of solution, are you referring to airloc activity in general or something more specific? My understanding is that changes in air pressure and/or ambient temp changes can affect airloc activity even when no fermentation is happening. Maybe there is more to that?

All my beers thus far have been slighlty hazy but I think that's due to my dry hopping in the chilled keg, or chilling in general. Could be from suspended yeast but I guess I don't mind so much. As long as it's not plugging the dip tube  ;D

Offline denny

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Re: A bunch of questions on harvesting yeast
« Reply #27 on: November 15, 2020, 04:18:23 PM »
By the way, anyone with a pulse has heard AB's claim that Bud is beechwood aged.  However, in this case the beechwood adds no flavor because the aging process is based on the old practice of using beechwood to clarify beer.  The aging tank  (a.k.a. chip cask) is filled with boiled beechwood chips. The purpose of the chips is to increase the surface area on which AB's yeast culture can settle.  That is their sole purpose.

I have read that they don't even use beechwood, but aluminum spirals, for the same reason.  I'm willing to believe that may be apochryphal.
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Offline Saccharomyces

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Re: A bunch of questions on harvesting yeast
« Reply #28 on: November 18, 2020, 02:48:40 PM »
As far as CO2 coming out of solution, are you referring to airloc activity in general or something more specific? My understanding is that changes in air pressure and/or ambient temp changes can affect airloc activity even when no fermentation is happening. Maybe there is more to that?

I am attempting to differentiate between dissolved CO2 coming out of suspension and CO2 actually being produced.  The beauty of using a clear fermentation vessel is that it is easy to determine when fermentation is complete because there is a color change, starting at the top, when fermentation is complete. The thing to remember is just because a batch has reached terminal gravity does not mean the yeast culture is done doing its job.  Most cultures will continue to consume metabolic waste products for a period of time after it appears that fermentation is complete.  That is why cold crashing as a practice is non-optimal for amateur brewers who have the gift of time.  I have never had a cold-crashed beer that tasted as good as one that was allowed to settle on its own schedule.  Amateur brewers do not need to cold crash because we are not beholden to bean counters. Our hobby is not driven by profit and loss.

Offline BrewBama

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Re: A bunch of questions on harvesting yeast
« Reply #29 on: November 18, 2020, 08:20:06 PM »
Once the yeast activity stops I package because there’s no O2 protection after that point. When I see a flatline on the data logger, I package and cold crash.  I don’t want the beer sitting in a fermenter any longer than it takes to actively ferment potentially exposing it to O2 pickup.


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