Author Topic: Harvested Yeast Slurry  (Read 1058 times)

TXFlyGuy

  • Guest
Harvested Yeast Slurry
« on: March 20, 2020, 06:36:06 am »
We have a very nice yeast slurry (Czech Pils), just harvested from a previous brew.

It's about 1.5 pints (+/-). Do we need to "feed" this to wake it up, or can we simply re-pitch it as is into our next brew?

Offline BrewBama

  • Official Poobah of No Life. (I Got Ban Hammered by Drew)
  • *********
  • Posts: 5327
Re: Harvested Yeast Slurry
« Reply #1 on: March 20, 2020, 06:54:04 am »
I recommend a ‘shaken, not stirred’ (SnS) starter (below):

Vitality Starter

 author S. cerevisiae

All one needs to make a well-shaken starter is a sanitizable vessel that is at least four times the volume of the starter being prepared, a sanitizable screw-on cap for the vessel, and a funnel.  I do not know if anything comparable is available in the UK; however, one U.S.-gallon glass jugs (demijohns in UK speak) are plentiful in the United States.   Home brew supply stores sell plastic replacement caps for these jugs that can be sanitized (38mm polyseal screw top caps).  If one has money to burn, a 5L borosilicate glass media bottle like I currently use is a very nice toy.  However, 5L media bottles can cost prohibitive when purchased new.  I acquired my current 5L media bottle as unused laboratory surplus, and it was not cheap.  I used a 1-gallon glass jug for a very long time before switching over to using a 5L media bottle.

Preparing the starter medium (a.k.a. starter wort)

The starter medium is prepared like one would prepare a starter any other way.  A 10% weight/volume solution is made by mixing 100 grams of pale DME into a little more than 1L of water.  The goal here is to end up with 1L of media after the solution has been boiled and cooled to room temperature.  I boil the solution for 15 minutes in a 3-quart stainless steel sauce pan (A U.S. quart is slightly smaller than a liter).  The media is chilled in the sauce pan with the cover affixed using an ice water bath in my kitchen sink. 

Sanitizing the starter vessel, screw-on cap, and funnel

The starter vessel, screw-on cap, and funnel should be sanitized while the medium is boiling and chilling. While I use bleach and StarSan, feel free to use your preferred sanitizer.  It is critical that the funnel is sanitized as well, and that one does not touch the inside surface of the funnel after it has been sanitized.

Note: One thing that I like to teach home brewers is to get into the habit of wiping the lip over which yeast or nutrient will be poured with an alcohol saturated cotton ball before decanting yeast, medium, or supernatant (supernatant is the clear liquid that lies above the solids in a starter, yeast crop, or a batch of beer).  Wild microflora (yeast, mold, and bacteria) rides through the air on house dust.  What we want to do is ensure that we do not drag any dust that may have come to rest on the pouring lip of the container that we are decanting into a vessel in which we intend to grow a culture or ferment a batch of beer.  This precaution makes sense If one thinks about what a nurse or doctor does before giving one an injection.  The reason why a doctor or a nurse cleans an injection site with an alcohol wipe before giving one an injection is to prevent the needle from dragging microflora that is on one’s skin into the injection site.

Pouring the starter medium

After placing the funnel in the starter vessel, one should wipe the pouring lip of the sauce pan in with an alcohol saturated cotton ball before pouring the starter medium into the starter vessel.  I use 70% or 90% isopropyl alcohol.  I used to use 95% ethanol (a.k.a. grain alcohol).  However, my state outlawed its sale due to teenagers and young adults abusing it.  Any 140 proof or better clear spirit will work.  Please do not use methylated spirits. 


Inoculating the starter medium

If using a White Labs vial, wipe the pouring lip of the vial with an alcohol saturated cotton ball before pouring the yeast culture into the starter vessel.   If using a Wyeast smack pack, wipe the outside of the smack and the blades of the pair of scissors that one is using to cut a corner off of the smack pack with an alcohol saturated cotton ball before making the cut, and wipe the cut edge of the smack pack with an alcohol saturated cotton ball before pouring the contents of the smack pack into the starter vessel.


Caping and shaking

Here’s where my method differs from the way the average home brewer makes a starter.  The reason why a vessel with a screw-on cap is necessary with this method is because one is going to shake the culture very vigorously for about a minute.  I usually tell brewers to shake the starter vessel like it owes you money (think mafia enforcer).  The goal here is to attempt to turn the media into foam. That's why the vessel has to be at least four times the volume of the starter.  One should then allow the starter to sit for around thirty minutes before loosening the cap to allow the foam to drop.

A well-shaken starter in a 5L media bottle



Pitching the starter

Pitching is one area where most home brewers get it completely wrong.  A starter is not a small batch of beer.  It is a yeast biomass growth medium.  The goal here is to grow the culture to maximum cell density and then pitch it.  Maximum cell density occurs at high krausen.  Beyond that point, all cell reproduction is for replacement only. Yeast taken at high krausen is much healthier than yeast that is taken from a sedimented starter or batch of beer.  That’s why traditional breweries crop yeast at high krausen.  Allowing a starter to ferment out and settle places the cells in the yeast equivalent of hibernation where they will have to undo survival-related morphological changes that occurred at the end of fermentation as well as completely replenish their ergosterol and unsaturated fatty acid reserves after being pitched. 

High krausen should occur within 12 to 18 hours after pitching the starter.  The yeast biomass grows exponentially, not linearly.  The yeast cell count grows at a rate of 2^n, where the symbol “^” means raised to the power of, and n equals the number of minutes that have elapsed since the end of the lag phase divided by 90; hence, the difference in propagation time between 200B cells and 400B cells can be as little as 90 minutes.


Sent from my iPad using Tapatalk

Online denny

  • Administrator
  • Retired with too much time on my hands
  • *****
  • Posts: 25709
  • Noti OR [1991.4, 287.6deg] AR
    • Dennybrew
Re: Harvested Yeast Slurry
« Reply #2 on: March 20, 2020, 07:56:10 am »
If it's just harvested, pitch as is.  I don't worry about restarting it unless it's been in storage for a while.
Life begins at 60.....1.060, that is!

www.dennybrew.com

The best, sharpest, funniest, weirdest and most knowledgable minds in home brewing contribute on the AHA forum. - Alewyfe

"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts." - Bertrand Russell

Offline Kevin

  • Brewmaster
  • *****
  • Posts: 607
  • Great beer. Less work. More fun.
Re: Harvested Yeast Slurry
« Reply #3 on: March 20, 2020, 08:57:22 am »
I have used harvested yeast that I stored in a mason jar and refrigerated 5-7 days after harvest and all I did was decant what was on top first.
“He was a wise man who invented beer.”
- Plato

Offline mdyer909

  • Cellarman
  • **
  • Posts: 78
Re: Harvested Yeast Slurry
« Reply #4 on: March 21, 2020, 07:27:41 am »
If it’s been sitting around for a while I just proof it like you would yeast for baking.  If it starts bubbling right up in 10 minutes or so I figure it’s good to go.

TXFlyGuy

  • Guest
Re: Harvested Yeast Slurry
« Reply #5 on: March 21, 2020, 05:15:45 pm »
The yeast was freshly harvested, maybe 5 days or so.
It was active when the decanting was done. Added some sterile wort to stir up the thick peanut butter like paste. Then dumped the whole thing into the fermenter.
It took off immediately, exactly what we hoped for.

Offline brian_welch

  • Cellarman
  • **
  • Posts: 47
  • Holden MA
Re: Harvested Yeast Slurry
« Reply #6 on: March 24, 2020, 08:36:03 am »
If it's just harvested, pitch as is.  I don't worry about restarting it unless it's been in storage for a while.

Define "a while." I have two mason jars of yeast slurry that I harvested from a batch of Kellerbier in May 2019.  The yeast wasn't washed or rinsed--just yeast and beer poured into sanitized mason jars and then placed in the fridge.

I started using this yeast in January 2019 to brew a Franconian Dunkel (which took first place in the Boston region round one of the NHC for Dark Lager), then was immediately repitched for a Rauchbier, and was then repitched for the Kellerbier (that I served on club night at NHC).

It started out as WLP830 with a starter that I stepped up once but didn't get the activity I was hoping for so I added a packet of 34/70.

Then I went on a brewing hiatus until this winter (thank you Anvil Foundry for making my brew day shorter and easier so I can find time to brew).

My plan (unless people think it is a bad idea) is to make a big starter and see what it does.  I have a bunch of cans of Propper canned wort from NHC, so starters will be easier than ever. I'll let you know how it turns out.
Brian Welch
WIZARDS (Worcester Incorporated Zymurgists Advancing Real Draughts)

ON TAP:
Dark Mild
1879 Kulmbacher
Rauchbier

ON DECK:
EisKulmbach

Offline HopDen

  • Brewmaster
  • *****
  • Posts: 765
Re: Harvested Yeast Slurry
« Reply #7 on: March 24, 2020, 08:51:09 am »
If it's just harvested, pitch as is.  I don't worry about restarting it unless it's been in storage for a while.

Define "a while." I have two mason jars of yeast slurry that I harvested from a batch of Kellerbier in May 2019.  The yeast wasn't washed or rinsed--just yeast and beer poured into sanitized mason jars and then placed in the fridge.

I started using this yeast in January 2019 to brew a Franconian Dunkel (which took first place in the Boston region round one of the NHC for Dark Lager), then was immediately repitched for a Rauchbier, and was then repitched for the Kellerbier (that I served on club night at NHC).

It started out as WLP830 with a starter that I stepped up once but didn't get the activity I was hoping for so I added a packet of 34/70.

Then I went on a brewing hiatus until this winter (thank you Anvil Foundry for making my brew day shorter and easier so I can find time to brew).

My plan (unless people think it is a bad idea) is to make a big starter and see what it does.  I have a bunch of cans of Propper canned wort from NHC, so starters will be easier than ever. I'll let you know how it turns out.


Make the big starter! See how it looks. If it came back to "life" use it. I keep harvested slurries in my fridge for months and months and have never had any of them NOT work. I have 830 and 34/70 in my fridge and my 34/70 is on gen5 with no perceptible changes, as far as I can tell.

One small bit of advice is to have fresh dry yeast on hand just in case but I'll go out on a limb and state you're going to be surprised.

Good Luck!

Online denny

  • Administrator
  • Retired with too much time on my hands
  • *****
  • Posts: 25709
  • Noti OR [1991.4, 287.6deg] AR
    • Dennybrew
Re: Harvested Yeast Slurry
« Reply #8 on: March 24, 2020, 09:17:38 am »
If it's just harvested, pitch as is.  I don't worry about restarting it unless it's been in storage for a while.

Define "a while." I have two mason jars of yeast slurry that I harvested from a batch of Kellerbier in May 2019.  The yeast wasn't washed or rinsed--just yeast and beer poured into sanitized mason jars and then placed in the fridge.

I started using this yeast in January 2019 to brew a Franconian Dunkel (which took first place in the Boston region round one of the NHC for Dark Lager), then was immediately repitched for a Rauchbier, and was then repitched for the Kellerbier (that I served on club night at NHC).

It started out as WLP830 with a starter that I stepped up once but didn't get the activity I was hoping for so I added a packet of 34/70.

Then I went on a brewing hiatus until this winter (thank you Anvil Foundry for making my brew day shorter and easier so I can find time to brew).

My plan (unless people think it is a bad idea) is to make a big starter and see what it does.  I have a bunch of cans of Propper canned wort from NHC, so starters will be easier than ever. I'll let you know how it turns out.

For me, "a while" is 3-4 weeks.  I've gone as long as 5 months but I don't recommend it.
Life begins at 60.....1.060, that is!

www.dennybrew.com

The best, sharpest, funniest, weirdest and most knowledgable minds in home brewing contribute on the AHA forum. - Alewyfe

"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts." - Bertrand Russell

Offline brian_welch

  • Cellarman
  • **
  • Posts: 47
  • Holden MA
Re: Harvested Yeast Slurry
« Reply #9 on: April 21, 2020, 04:30:26 pm »
I finally finished the bathroom renovation I've been working on for months (you don't want to be quarantined with a wife and two teenage daughters with one bathroom) so I had time to brew.  I did a two-stage starter with my year-old yeast and it looked good and smelled good (or at least smelled the way yeast is supposed to smell). I pitched it into my 1.045 Kellerbier and it is chugging away and smelling wonderful. I'll report back when it is time to drink but so far, so good!
Brian Welch
WIZARDS (Worcester Incorporated Zymurgists Advancing Real Draughts)

ON TAP:
Dark Mild
1879 Kulmbacher
Rauchbier

ON DECK:
EisKulmbach