Harvested yeast - save a portion from slurry or from starter?

[ILMSTMF]

I've harvested quite a bit from my last batch; more than I need to build a sufficient starter for the next brew. (See photos here: https://www.homebrewtalk.com/showpost.php?p=7761341&postcount=32)
I want to keep it going for a few brews. Do I...

A) Take a portion of the slurry out of the jar leaving a large volume of slurry behind. Then build a sufficient starter for next brew.
B) Same as above but dispose of the remaining slurry in jar and harvest from the primary.
C) Same as A) except overbuild starter, harvest from that, dispose of original slurry.
D) A combination of above; you tell me because my brain is fried.

Ultimately, I'm trying to figure out the best method to retaining this yeast for reuse that also provides best viability. THANK YOU!

 

[IslandLizard]

A) will work fine.
If that's the whole harvested cake in that jar, use about 1/4 to a 1/3 of it in your next batch. A yeast calc will give you an indication how many cells are viable in that slurry. If you pitch within 4 weeks (or even 6) after harvest, you won't even need a new starter as there are plenty of good cells mixed in the trub.

If you are making a new starter, use only as much slurry as the yeast calc tells you. Adding too much yeast to your starter vessel (high cell density) will actually curb their growth.

B) Each time you ferment it becomes a new generation. After x generations your yeast may start to show problems. x is determined by many factors, but 10 is about the max. Age is also a factor.

I discovered clarity problems after 5 gens (and their incurred age). The yeast wasn't floccing out as much anymore, even after 4 weeks at 34F. Tossed all the old yeast and started with new packs for each of those yeasts (1968, 1272, 1099). I overbuilt starters and saved them out in small 4oz jars topped up with starter beer.

I reuse yeast cakes a few times (2-5), then build a new oversized starter from one of those 4 oz jars for a new series.

For example one of my ESBs was extremely trubby for some reason, so after filling the keg I simply dumped the yeast cake. No point in saving it as I have plenty of that yeast around now.

C) Overbuilding starters and using the leftover to build a new starter, etc. is always better than reusing harvested yeast that was stressed. High gravity, high hops, underpitching, etc. can stress yeast. Also leaving (strong) beer on a primary yeast cake for 3-4 weeks does not improve the yeast quality either.

D) RDWHAHB

 

[TeamAshBrewing]

What IslandLizard said.
I also keep 2-3 house strains around, usually WLP 001, 007, and 090. Build a 2L starter, split, use half for the current batch (depending on needed cell count I might make 2nd starter and use the whole amount) and put half in the fridge. Repeat the process for the next brew.

 

[ILMSTMF]

Alright. So I'm going with option C. Will overbuild a starter using the harvested yeast. Will retain (harvest) the leftover yeast to be used for future starters/brews. Am I right to think that this method will be best with respect to viability? I figured it's in the same family as overbuilding the starter from a fresh vial of yeast. Would doing this mean "just throw out the original slurry"?
Also, I don't intend to take this yeast beyond a third brew simply based on the styles I have planned in near future. :-D

 

[IslandLizard]

Alright. So I'm going with option C. Will overbuild a starter using the harvested yeast. Will retain (harvest) the leftover yeast to be used for future starters/brews. Am I right to think that this method will be best with respect to viability? I figured it's in the same family as overbuilding the starter from a fresh vial of yeast. Would doing this mean "just throw out the original slurry"?
Also, I don't intend to take this yeast beyond a third brew simply based on the styles I have planned in near future. :-D

1. Build a 2 liter starter from some of that trubby/hoppy slurry. Use yeast calc for approx. amount of slurry needed, probably 2-4 tablespoons, 1-2 oz.
   
   
2. Chill in fridge, after 1-3 days decant most of the clear starter beer. You can pour it into a well sanitized (glass) container to top of your storage jars in Step 3.
   
   
3. Swirl up new slurry, divide 3/4 over 3 small jars (I use 4 oz mason/jelly jars). Top off with the starter beer saved from Step 2. Screw lid on, label, and store those jars in fridge.
   
   
4. Make new 2l starter from the leftover 4th part. After chilling and decanting, pitch 3/4 of that into your new beer, save 1/4 for your next starter.
   
   
5. Etc. Etc.
   That way you always have 4 jars with fresh yeast in stock.

Use very good sanitation whenever you handle yeast so it doesn't get infected.

 

[ILMSTMF]

Brilliant, thank you!!
Step 2 was the next question I had - about what to do about topping up the jars with starter beer. Thanks!

 

[ILMSTMF]

1. Swirl up new slurry, divide 3/4 over 3 small jars (I use 4 oz mason/jelly jars). Top off with the starter beer saved from Step 2. Screw lid on, label, and store those jars in fridge.
   
   
2. Make new 2l starter from the leftover 4th part. After chilling and decanting, pitch 3/4 of that into your new beer, save 1/4 for your next starter.
   

One more - of those small jars, can I assume how many billion cells are in each or is that something that is factored by using the calculator?
In general, how many of those jars are you using to pitch into a 5 gallon batch? Thank you!

 

[IslandLizard]

"just throw out the original slurry"?

Also, I don't intend to take this yeast beyond a third brew simply based on the styles I have planned in near future. :-D

You could keep some of that original trubby slurry, if you want. It will be good for at least 6 months if stored in fridge. Or dump it and use the fresh yeast in your new storage jars instead. Save the space in your fridge for another house yeast strain.

Not planning on using this yeast after the 3rd brew? What number/strain is it? Many yeasts are very versatile and can be used in many styles. Nothing wrong with using a British ale yeast in an American IPA.

 

[ILMSTMF]

Yup, exactly that. 1318 London; just used it in a NE IPA. What I'm struggling with is matching it to proper styles beyond the next couple brews I'll be doing. Plus, I only brew about every other month. So I figured the yeast wouldn't be viable by the time I get to batch four or five. Thanks!

 

[IslandLizard]

One more - of those small jars, can I assume how many billion cells are in each or is that something that is factored by using the calculator?
In general, how many of those jars are you using to pitch into a 5 gallon batch? Thank you!

I really like using Homebrew Dad's Yeast Calc or YeastCalc's.

I target for 300-400 billion cells in a starter made from a fresh pack. So when I split that into 4s, 75-100 billion cells per 4 oz jar.

When that first propagation starter is ready to be split, after pouring off most starter beer, I use a scale to weigh the slurry at hand. Divide into 4s (sometimes 3s) about 75-100 grams per jar, each containing 75-100 billion cells. I have recorded the tare weight of each 1/2 gallon jar and flask I use for making starters.

The origination date is on the jars' labels, including its generation (st1 = starter 1) and estimated cell count in billions, e.g., 1968 st1 - 8/1/16 - 90.

Each of those 4 oz jars can easily generate 200-300 billion cells in the next starter, depending on their age and estimated cell count since last time generated.

200 billion cells is enough for a 5.5 gallon batch of 1.050. 300 billion for 5.5 gallons at 1.080.

If I need a larger pitch, or a double batch, I may use 2 jars to make 2 starters at the same time, with some extra left over after the pitch to fill 1 or 2 of those 4 oz jars again to replenish stock. Those jars saved have a new generation on them, e.g., 1968 st2 - 10/12/16 - 80. That way I keep my yeast stash's dates fairly recent.

It's really much easier than it looks.

 

[IslandLizard]

Yup, exactly that. 1318 London; just used it in a NE IPA. What I'm struggling with is matching it to proper styles beyond the next couple brews I'll be doing. Plus, I only brew about every other month. So I figured the yeast wouldn't be viable by the time I get to batch four or five. Thanks!

I'm sure you can keep that yeast alive in the fridge for a year, then consolidate the slurry of those 3 or 4 jars, and build a new starter. That's a great yeast for so many styles.
Or look into freezing yeast if you need longer storage. Or just buy a new fresh pack when you get the urge for brewing with London Ale yeast again.

Once you start brewing more you want to keep a few yeasts on hand. The past 3 months I served 6 kegs at various homebrew events. They were pretty much emptied, except for one, the "Toasted Wit."

 

[ILMSTMF]

I really like using Homebrew Dad's Yeast Calc or YeastCalc's.

I target for 300-400 billion cells in a starter made from a fresh pack. So when I split that into 4s, 75-100 billion cells per 4 oz jar.

When that first propagation starter is ready to be split, after pouring off most starter beer, I use a scale to weigh the slurry at hand. Divide into 4s (sometimes 3s) about 75-100 grams per jar, each containing 75-100 billion cells. I have recorded the tare weight of each 1/2 gallon jar and flask I use for making starters.

The origination date is on the jars' labels, including its generation (st1 = starter 1) and estimated cell count in billions, e.g., 1968 st1 - 8/1/16 - 90.

Each of those 4 oz jars can easily generate 200-300 billion cells in the next starter, depending on their age and estimated cell count since last time generated.

200 billion cells is enough for a 5.5 gallon batch of 1.050. 300 billion for 5.5 gallons at 1.080.

If I need a larger pitch, or a double batch, I may use 2 jars to make 2 starters at the same time, with some extra left over after the pitch to fill 1 or 2 of those 4 oz jars again to replenish stock. Those jars saved have a new generation on them, e.g., 1968 st2 - 10/12/16 - 80. That way I keep my yeast stash's dates fairly recent.

It's really much easier than it looks.

Yes, my head is spinning reading this but in practice, I'm sure it will have me saying "duh".
Brilliant to record the tare weight of your empties! I'll use the tare function of my digital scale, safe to do, would you agree? DERP, your point of reference is for weighing a vessel that has the slurry in it already so can't tare it to weigh slurry only, got it.
Oh wow, I like that first calculator you linked to. It gives you option to overbuild for harvesting, brilliant. I appreciate that it recommends pitching a shaken starter into your wort rather than decanting before pitch. For me, that takes the guess work out of "is that starter beer I'm pouring off or yeast too? How much of this that's left behind will be pure yeast? How will I separate this for harvesting the rest after pitch?"
So, for generational reference, it looks like you are assuming a loss of 10% of the cells from original propagation (90b in st1 vs 80b in st2). Or did I misinterpret that? What is your purpose for noting what generation starter that particular jar contains? Are the older cells in ST1 a better/more viable collection than the "newer" cells in ST2?

I'm sure you can keep that yeast alive in the fridge for a year, then consolidate the slurry of those 3 or 4 jars, and build a new starter. That's a great yeast for so many styles.
Or look into freezing yeast if you need longer storage. Or just buy a new fresh pack when you get the urge for brewing with London Ale yeast again.

So, you're saying that if I take 4 of these small jars out for a whole year, it would be necessary to bring them together into a single starter due to the loss of viability over that period of time, right?
Thanks very much!!!

 

[IslandLizard]

Yes, my head is spinning reading this but in practice, I'm sure it will have me saying "duh".
Brilliant to record the tare weight of your empties! I'll use the tare function of my digital scale, safe to do, would you agree? DERP, your point of reference is for weighing a vessel that has the slurry in it already so can't tare it to weigh slurry only, got it.

Once you do it, you'll develop your own methods. Mine are just an example, the way I do it. Feel free to ignore or adapt anywhere you like.

Early on I discovered that weighing a vessel is the easiest way to obtain a decent sense of the amount of its content. For that, pre-weighing the tare of each vessel involved is needed. Even the weight of the lids are recorded, in case I have a jar with lid or one with a foil top.

Oh wow, I like that first calculator you linked to. It gives you option to overbuild for harvesting, brilliant. I appreciate that it recommends pitching a shaken starter into your wort rather than decanting before pitch. For me, that takes the guess work out of "is that starter beer I'm pouring off or yeast too? How much of this that's left behind will be pure yeast? How will I separate this for harvesting the rest after pitch?"

Working with either calculator gives you a good sense on how to manipulate starter volumes to get your desired cell counts. Now sometimes it's a shot in the dark if the yeast viability and activity is low. But you know you've propagated some, just not how much. Again, it's usually better to overpitch than underpitch grossly.

Re: Highlighted in red. Where did you see that? It is typically advised against to pitch whole starters without cold crashing and decanting, especially where large amounts of starter beer are involved. It dilutes your beer and adds bad tasting oxidized starter beer to your batch. For small amounts or pitching a yeast at high krausen to resurrect a stalled batch you can get away with it.

If you're building starters in multiple steps, cold crashing and decanting after each is the only method to keep your volumes at bay. Starter beer has nothing to bring to the party, except for topping off your storage jars to prevent oxidation (dead yeast is darker).

To concentrate the yeast into a slurry, after shaking, or better, stirring on a stir plate, place the starter vessel in the fridge for 1-3 days (cold crashing). Most if not all yeast will floc out to the bottom. Some yeasts will floc out as soon as you take them off the stir plate. Pour off the clear or mostly clear starter beer, leaving a little behind to swirl it up into a pourable slurry.

So, for generational reference, it looks like you are assuming a loss of 10% of the cells from original propagation (90b in st1 vs 80b in st2). Or did I misinterpret that? What is your purpose for noting what generation starter that particular jar contains? Are the older cells in ST1 a better/more viable collection than the "newer" cells in ST2?

Misinterpreted.
That was just an example. I just recorded the estimated cell count in that partial of st2 and is largely independent of what was in st1. In the calculator you just plug in your st1 cell count and the date it was generated. It will calculate remaining viable cells from there and how large a starter you need to generate the desired count for starter 2.

Keeping track of starter generations is useful as you don't want to exceed x amount of generations. I keep x at around 10 for starters made from starters (not used in real batch fermentations). Around 5 for reused yeast from previous batches. Or less, when I sense changes, like increased time needed to clear the beer when cold crashing, flavor, attenuation, and other factors.

So, you're saying that if I take 4 of these small jars out for a whole year, it would be necessary to bring them together into a single starter due to the loss of viability over that period of time, right?
Thanks very much!!!

Not necessarily, but it makes more sense when you have 3 or 4 jars of a stored strain in the fridge that are a year old. You may as well rejuvenate all of them at once by making a new starter from the whole lot. Their cell count is maybe only 10% of what they started with. So that original jar with st1 contained 90 billion cells is now down to 6% of that, 5 billion! If I use all 4 of those jars that at least gives me 4x5=20 billion to make my first step with, followed by a second to get my pitchable quantity plus some left over to store away again.

For long term storage and yeast banking, freezing yeast and/or slanting them are better and more manageable ways, especially when many strains are involved. Otherwise you'll have to make "rejuvenating starters" every 6-12 months, which has inherent limitations.

 

[ILMSTMF]

Early on I discovered that weighing a vessel is the easiest way to obtain a decent sense of the amount of its content. For that, pre-weighing the tare of each vessel involved is needed. Even the weight of the lids are recorded, in case I have a jar with lid or one with a foil top.



Working with either calculator gives you a good sense on how to manipulate starter volumes to get your desired cell counts. Now sometimes it's a shot in the dark if the yeast viability and activity is low. But you know you've propagated some, just not how much. Again, it's usually better to overpitch than underpitch grossly.

Re: Highlighted in red. Where did you see that? It is typically advised against to pitch whole starters without cold crashing and decanting, especially where large amounts of starter beer are involved. It dilutes your beer and adds bad tasting oxidized starter beer to your batch. For small amounts or pitching a yeast at high krausen to resurrect a stalled batch you can get away with it.



Misinterpreted.
That was just an example. I just recorded the estimated cell count in that partial of st2 and is largely independent of what was in st1. In the calculator you just plug in your st1 cell count and the date it was generated. It will calculate remaining viable cells from there and how large a starter you need to generate the desired count for starter 2.

Keeping track of starter generations is useful as you don't want to exceed x amount of generations. I keep x at around 10 for starters made from starters (not used in real batch fermentations). Around 5 for reused yeast from previous batches. Or less, when I sense changes, like increased time needed to clear the beer when cold crashing, flavor, attenuation, and other factors.



Not necessarily, but it makes more sense when you have 3 or 4 jars of a stored strain in the fridge that are a year old. You may as well rejuvenate all of them at once by making a new starter from the whole lot. Their cell count is maybe only 10% of what they started with. So that original jar with st1 contained 90 billion cells is now down to 6% of that, 5 billion! If I use all 4 of those jars that at least gives me 4x5=20 billion to make my first step with, followed by a second to get my pitchable quantity plus some left over to store away again.

Good tip on weighing the vessels.

OK, using homebrew dad's calculator, please see attached screen shot. So, I crash my starters and usually decant a good amount off of the slurry. I might have miswrote. Looking at the calculator, it's telling me to pitch 1.1L into the wort. That seems like a large volume based on a starter that began as 2L.

OK, so recording what generation starter is for reference to make sure you aren't taking the yeast past a certain generation, got it. Question is, how do you reference date of "manufacture"? Here is my big, ugly example:

• Harvest yeast from a starter that used a fresh vial.
• Store and label each jar as starter 1.
• Brew a month later; make and overbuild a starter from one of your jars.
• How do you label the yeast you harvested from that starter? 1 or 2?
• What would your plans be for the yeast harvested from the original vial-produced starter versus the generational starter produced a month later?

Thank you for all the helpful information!

 

[IslandLizard]

Good tip on weighing the vessels.

OK, using homebrew dad's calculator, please see attached screen shot. So, I crash my starters and usually decant a good amount off of the slurry. I might have miswrote. Looking at the calculator, it's telling me to pitch 1.1L into the wort. That seems like a large volume based on a starter that began as 2L.

OK, so recording what generation starter is for reference to make sure you aren't taking the yeast past a certain generation, got it. Question is, how do you reference date of "manufacture"? Here is my big, ugly example:

• Harvest yeast from a starter that used a fresh vial
Vial would be considered Generation 0. Manufacturing date determines viability in calculator as to how many live cells remain.
• Store and label each jar as starter 1.
Your new date is when the starter is made (or when you harvest). A few days is not significant.
• Brew a month later; make and overbuild a starter from one of your jars.
• How do you label the yeast you harvested from that starter? 1 or 2?
2. It's your second starter (2nd generation) from the original vial.
• What would your plans be for the yeast harvested from the original vial-produced starter versus the generational starter produced a month later?
They stay in the fridge until I either need one because the one I've been using has been used up (>4-5 gens or otherwise depleted/possibly infected, etc.), or I just want to rejuvenate my "reserve bank" because those slurries have been stored >6-9 months.

Thank you for all the helpful information!

Answers in-line in red. I hope they address your Qs.

If you're only going to use a certain yeast strain 3 or 4 times in the next 2 years, say every 6-9 months, keeping only one jar in reserve should suffice. There's no need to have 2-4 of them around only getting older and older and taking up shelf space.
Each time, before you brew, you make a new starter from that one reserve jar. Save some slurry out for the next time, 6-9 months from then. When saving out 100-150 billion cells for reserve each time, you should only need to make one 2 liter starter 6-9 months later, enough for a pitch and of course your new reserve jar. That way you won't need to do (multiple) step starters, and keeps the space taken up by yeast jars in your fridge manageable.

I have the 4 and 8 oz jelly mason jars stacked in a small cardboard box (similar to those provided by the USPS for priority mail). Mine fits perfectly between 2 shelves, with extra space on the side for some pint jars.

Regarding your screen cap, it's an alternative way many (most?) brewers use. They pour some of the newly made starter into a jar before they cold crash. The reasoning is it's a bit easier to pour off 1 pint or 1 liter of the (homogenous) starter than from a cold crashed (semi-thick) slurry.

The downside is, you'll end up with a fairly large jar in your fridge, and a few days later it contains a liter of starter beer with a little yeast layer (1/4") on the bottom. Also, beware, some yeasts floc out so fast, they become like egg drop soup or a rubbery sheet on the bottom when the starter is done, very difficult to make a homogenous slurry from that. I just prefer to work with the thicker (concentrated) slurries instead.

 

[ILMSTMF]

Brilliant, thank you for clearing that up! Makes sense, storing early generation and producing successive starters in their own line.

Thanks also for clearing up what the calculator is suggesting there. I'm fine with storing the larger vessels in the fridge for the short term - I'd have the 2L flask in the fridge anyway for crash.

Thanks!!