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calculator rinsed yeast & starter

K

KernelCrush

I have this 002 that's rinsed and almost a month old and want to start it up again.  I cant really find a way to figure the inoculation rate of washed volume into the starter wort. Last time I tried a few years ago I put in about 200 ml and put the flask and stir plate in the bathtub.  Glad I did.  I guess 1/2 that would be a start.  Is it just a WAG?
 
I hope you get an answer to this.  I rinse and re-use yeast quite a bit.  I probably pitch too much yeast, because I'm making WAG's due to not really knowing cell count.  I can tell you that I always make a starter with my rinsed yeast.  My lag times are short and my fermentations have been excellent, but it would be nice to make a somewhat educated guess at cell count.
 
To get it going I came up with a guess based on 100B cells in 35 ml in a fresh white labs tube then I doubled that to account for viability loss, and then adjusted for slurry density.
 
Did you guys forget that Jamil's yeast calculator has a slurry mode? For rough estimates 2.4 bil/ml. Viability drops offat about 10 percent per week.  Personally, I do not store slurry for longer than 2 weeks, because I don't want to add more than 20 percent dead yeast at pitching time.
 
Ps: for a 1.050 wort, 5.5 gallons, you would pitch 90ml of fresh slurry. Add 10ml per week of age.  So, your wag is pretty dang close. It is certainly within the variance caused by slurry density, and non yeast percentage. 

 
Hmmm... I keep answering part of your post.

If I were going to reuse slurry that was a month old, I would grow it fresh using a stepped starter method.  I would use a small amount of slurry to minimize the dead yeast.  Yeastcalc can help with figuring the steps. This would also help with the vitality of the colony. Use plenty of yeast nutrients. 
 
I thought the slurry mode was to calculate pitch rate into a batch.  The same number can be used as a slurry pitch rate to a starter?  Does that account for additional growth in the starter? 

I didn't want to use this old slurry and would normally toss it but it was a real performer on first use.  Reused it once last weekend but that's not ready to rack yet.  Was really pushing it and lost.  One look at it this morning and it was down the slop sink. 
 
KernelCrush said:
I thought the slurry mode was to calculate pitch rate into a batch.  The same number can be used as a slurry pitch rate to a starter?  Does that account for additional growth in the starter? 

I didn't want to use this old slurry and would normally toss it but it was a real performer on first use.  Reused it once last weekend but that's not ready to rack yet.  Was really pushing it and lost.  One look at it this morning and it was down the slop sink.

You are absolutely correct.  That calculator tells you the amount of slurry to pitch into a batch.  But, it tells you how many cells are in a certain volume of a certain age.  A small amount of work with Yeastcalculator.com will tell you how much slurry you need to grow into a final volume for pitching.  For example:

pitching into a 1.050 / 5.5 gallon beer requires 200 billion cells

My rule of thumb is no more than 20% dead cells, so that's 40 billion dead cells.  If my slurry is a month old, it has 40% dead cells.  In order to keep the dead cell count below 40 billion I can only use 100 billion cells of slurry (or less).  In real life, I'd be conservative and probably cut that in half again.  So, I'd start with 50 billion cells of slurry (which keeps the dead cell count around 20 billion).  If I'm growing a starter anyway....why not? 

I go over to MrMalty.com and use the slurry calculator.  I put in my target beer and slurry harvest date.  MrMalty says that I get 193 billion LIVE cells from 177 ml of slurry that is a month old.  That's 193/177 = 1.09 billion cells per mL of slurry.  In order to pitch 50 billion cells into my starter, I need to add 50 billion / 1.09 billion per mL = 46 mL of slurry. 

Note that MrMalty estimates the viability at 50% (rather than my rough 40% estimate). 

So, back to yeastcalculator.com.  In the liquid yeast properties, set the initial cell count to 50 billion, and uncheck the calculate viability from date checkbox.  Also set the viability to 100% because we already took care of that over at MrMalty. 

In each of the "step" sections set your aeration method to whatever you use.  I use a stirplate, and I've always used JZ's calculation method (I need to look into Kai's data....maybe I need to change).  I have a 1L flask, so I set my starter volume to 800 ml. 

For the first step, Yeastcalculator says that I from my initial 50 billion cells, I will end up with 141 billion cells total.  So, I'm not to the 200 billion required, yet.  I will need to decant the first step and add more wort to grow the remaining 50 billion cells. 

So, I update the second step, as before.  If I grow another full step (800 ml) then I end up with 247 billion cells---slightly over-pitching.  By backing the volume down to 500 ml, I end up with 199 billion cells.  Incidentally, when you decant you don't have to decant every last drop.  You really only need to decant as much as you are going to add back.  In this example, 500 ml in order to make room in the flask. 

Also, if you have a larger flask (2+ liters) you wouldn't need the second step.  A 1.7 liter single-step starter would grow all the needed cells to pitch 199 billion cells. 

I used to do this a lot---back when I used to harvest and freeze my own yeast.  I would grow a large quantity of yeast and then freeze 12.5 ml of slurry in another 12.5 ml of glycerin.  Then I would grow these small yeast quantities up into full starters for pitching.  Its a hassle that is only worth it for hard to find strains like the platinum strains or maybe something you harvest from a commercial bottle. 

 
Once again I bow to the master.  That's a sticky for sure.

Since we are kinda on the topic.  Another thing I wonder about is the date to use when calculating viability for harvested yeast.  One of JZ shows he says to use the floc date as opposed to the actual harvest date which makes sense to me.  It doesn't matter if they are under beer or under sterile water, time=loss of viability. Creates a conundrum of whether to harvest quick for viability or leave in the primary to perform clean-up.  Can you figure only the yeast in suspension is doing the actual cleanup?  Seems the flocculated yeast at the bottom isn't doing much at that point. 
 
KernelCrush said:
Once again I bow to the master.  That's a sticky for sure.

Since we are kinda on the topic.  Another thing I wonder about is the date to use when calculating viability for harvested yeast.  One of JZ shows he says to use the floc date as opposed to the actual harvest date which makes sense to me.  It doesn't matter if they are under beer or under sterile water, time=loss of viability. Creates a conundrum of whether to harvest quick for viability or leave in the primary to perform clean-up.  Can you figure only the yeast in suspension is doing the actual cleanup?  Seems the flocculated yeast at the bottom isn't doing much at that point.

Ha!  I'm hardly "the master".  Brewfun certainly has me covered.  But, thanks. 

I think that's mostly true, floc date = harvest date, for viability calculations.  However, there is a difference.  When the yeast floc's it is out of oxygen, and has some glycogen stores that it keeps for survival.  The yeast is cold and has no oxygen, so it goes dormant.  The act of harvesting warms up the yeast, and exposes it to a new source of oxygen which will revive the yeast and spur them to use up some of their glycogen reserves. 

As a result of this, the yeast will be left weaker and less able to survive after harvest than if left undisturbed under a blanket of beer.  Exactly what this magnitude of difference is, I don't know.  Maybe its a 2% increase in rate of decay, maybe its 20%. 

Also, while its true that the yeast cake doesn't have the same contact with the beer that cells in suspension do...it would be a mistake to assume that they don't have an impact.  Try a split batch, and move one to secondary after the bulk of the yeast has floc'ed out.  Then chart the progress to final gravity.  You will see two or three things:

1.  The beer that was racked will progress to FG more slowly.  The beer that remained in primary will reach terminal gravity several days to a week sooner. 

2.  The beer that was racked will probably not reach the same FG.  Ie, it will end a couple points higher than the oen that remained in primary.

3.  In a blind triangle taste test you may detect more diacetyl (buttery) and/or acetaldehyde (green apple) in the beer that was racked.  This can be quite variable and is dependant upon how well you managed the other fermentation variables (pitching rate, pitching temp, ferm temp, etc).  In other words, if you did a good job otherwise, the simple act of racking early won't cause a problem that is detectable.  BUt, if the early fermentation period wasn't managed well....then racking to secondary will allow these problems through to the finished beer.

This is the point I've made several times about racking to secondary. It doesn't CAUSE you to end up with problems in the final beer.  However, it removes some of the insurance against a mistake or two during other parts of the process. 

As homebrewer's we rely on several estimated fermentation parameters.  We don't have the lab measurements that the pro's do.  We don't make the same beer every day or every week, 350 days a year.  The pro's can rack to a bright tank in 7 days (for example) because they can take measurements and KNOW that they won't have a problem.  The pro's lose money by going slow---process optimization is important. 

There's very little (basically none) risk for a homebrewer in leaving it sit a little longer to ensure everything is a-ok before moving it.
 
Great advice..... I have made lagers or pilners for my last 4 batches using the stepped starter method.
Since you need lots of yeast for these beers, I do a 1500 ml & 2500 ml with stir plate. Decanting the 2500 ml, chilling down kettle wort to pitching temp and stirring again. You don't need much stirring because fermentation in the flask will take off like a rocket. Keep an eye on it!!!!
Now my lagers & pils are at a level where I am very happy. A huge improvement!

My fermentation is active is active within 6 hrs.
Search Tasty's fermentation schedule....it has given me great results in 10 days. I let the beer cold crash and then brite cornys longer than the fermentation, then run it through a medium filter. Four beers, and no chill haze! I changed to mashing pils 90 minutes plus mash out 20 min followed by a more vigorous boil. I have been consistently at 50% gravity on day 3, 2 more days to 25%, 1 more day to 10%, terminal 4 more days. Temp wise that's 55, 58, 62, & 68 degrees as Tasty states.

Sorry I got off topic, just loving this beer!

Gary
 
I can tell you that I always make a starter with my rinsed yeast.take a look to this site http://www.swisscubancigars.com/blog/new-trend-matching-cigars-food/ but it would be nice to make a somewhat educated guess at cell count. ;)
 
Oh for Christ sakes! Just throw it (the yeast) in and don't worry about it. If you are that worried just blast some oxygen into it and let it go (or shake the piss out of the fermenter if you use a small one or, splash the crap out of it when you are filling it if you have a large one). If it don't take off you are using some lame, weak ass, yeast. In 23 years of brewing I have never had a yeast that didn't take off. It ain't that big of a deal. I re-pitch all the time. It just keeps getting stronger and stronger. One strain of 1056 we pitched 9 times then just got tired of brewing American ales. Commercial breweries use strains that are like 200 years old. Keep it clean and throw that crap in. It will be fine.
 
Kernelcrush -  I just finished the Yeast book by White and Zainasheff. This is a great book for those of use harvesting and reusing yeast.  Tom_Hampton knows his stuff too, I think maybe he's read a little :)  You can estimate cell count by weight too. 

Freak -  We are not trying to repeat the sins of our forefathers.  We are trying to make outstanding beer and learn some of the science and biology around the processes in ingredients.  there are right ways and wrong ways to harvest, prepare and store yeast.  We want to be sure we are harvesting the best cells and taking the right precautions to keep them healthy and ready to use on our next batch.  We are not keen on spending a day making beer to risk having to toss it out because we didn't take the time to understand the most vital part of making beer.  After all, all we do is make sugar water.  yeast make beer. 
 
Oh for Christ sakes! Just throw it (the yeast) in and don't worry about it.

And to think all these years I've been pitching instead of throwing!  Its no small wonder I have questions.
 
Yeast book by White and Zainasheff

I read it but I cant even remember when.  Its on my list of re-reads.  Water, too, if I can stay awake.  Thanks
 
KernelCrush said:
I read it but I cant even remember when.  Its on my list of re-reads.  Water, too, if I can stay awake.  Thanks

I just started Water by Palmer and Kaminski.  Still in the Foreward. 
 
I just finished the Yeast book by White and Zainasheff. This is a great book for those of use harvesting and reusing yeast.  Tom_Hampton knows his stuff too, I think maybe he's read a little :)  You can estimate cell count by weight too. 

I checked the contents & index in the yeast book and skimmed appropriate sections, but I didnt see anything on estimating cell count by weight.  Its likely there somewhere, but how do you do this?  The first thing that jumps to mind is the yeast/water/beer concentration would foible? your weights.
 
KernelCrush said:
I checked the contents & index in the yeast book and skimmed appropriate sections, but I didnt see anything on estimating cell count by weight.  Its likely there somewhere, but how do you do this?  The first thing that jumps to mind is the yeast/water/beer concentration would foible? your weights.

I am 90% sure it was in the estimating yeast densities section.  I recall it was about commercial breweries pitching by weight. 
 
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