Guide to Yeast Slurry, Yeast Starter, Viability Pictorial

[HomebrewPadawan]

After much, much, much reading, I believe I now have a way to figure out how much viable yeast I have when using a cold stored rinsed jar of yeast, and how to apply that information to the yeast calculators Mrmalty and YeastCalc to find how many steps is required to achieve the appropriate pitching rate for any brew.
Here is my step by step process. Please follow along and let me know what you think (this should help a lot of people because I know I have been infatuated with finding a solution to this for a while now...and I assume many of you have too)!

For this example; lets say you are trying to brew 5 gallons of a 1.090 brew with some yeast that you rinsed some time ago...

Step 1: Rinse yeast (there are plenty of threads explaining the principals and techniques behind this already...more commonly called 'yeast washing')
Step 2: Date jar and store in refrigerator for future brew session



Step 3: Plan a brew day and your yeast starters!
Step 4: Now comes the fun part, it is time to manipulate mrmalty.com to tell you how many viable yeast cells you have in your slurry.
-Visit http://www.mrmalty.com/calc/calc.html
-click on the "Repitching from Slurry" tab
-enter the "Harvest Date" as the date you rinsed and stored your slurry (example jar 03/02/2014). You will see the "Viability %" change in accordance to how long ago you made your jar, in this example the 2week+ old slurry viability is 69% (the longer you keep the rinsed yeast, the less viable it becomes)
-move the "Yeast Concentration billion/ml" slider to your slurry appropriate value (I use a value of 4.0 because the jar has been refrigerating and is quite compact)
-move the "Non-Yeast Percentage" slider to your slurry appropriate value (I use a value of 10 because I feel I rinse well and can visually see almost nothing but yeast in my jars)
-Mrmalty shows that we need 305 billion yeast cells to ferment this 5 gallon batch of 1090 OG brew. With a 69% Viablitly, we need 122ml of slurry under the "# ml of yeast needed" section. Problem is I don't have that much...what can a home brewer do??? Step up what I do have!



Step 5: Time for a tiny bit of math...
-We have (roughly) 25ml of slurry in the example jar, a Yeast Concentration value of 4.0 billion cells/ml of slurry, a Non-Yeast Percentage value of 10%, and a Viability of 69%, so...
25ml of slurry x 4bil/ml = 100 billion total cells
100 billion total cells x (1-10%) = 90 billion yeast cells
90 billion yeast cells x .67 viability rate = 60.3 billion viable yeast cells
Step 6: Now it's time to jump over to YeastClac and find out how we are going to build 60.3 billion cells into the 305 billion cells we need for this brew example.
-under the "Liquid Yeast Properties" section uncheck the "Calculate Viability from Date" box
-enter your "Initial Cell Count" as 60.3 and "Viability" as 100%
-under "1st Step" section choose your appropriate yeast starter method (stir plate is best, that's a given, but I don't have one so I choose "Intermittent Shaking") and set the "Starter Volume" value to 1 liter. You can see at the end of this starter you should have 144 billion "Total Cells at Finish"
-under the "2nd Step" section choose your appropriate yeast starter method (again, I chose Intermittent Shaking) and play with the "Starter Volume" size until you have the correct "Total Cells at Finish" in the tab. In this example it took a second starter of 1.85 liters to step up the 144 billion cells to the approximately 305-306 billion yeast cells needed to ferment this example brew.



So that's it. You now have stepped up a small amount of rinsed yeast and made it good and healthy enough to ferment a 1090 OG brew!
Please let me know what you guys think!!

 

[HomebrewPadawan]

I thought I would add this link to a YeastCalc page that still works!

http://web.archive.org/web/20140108174714/http://yeastcalc.com/

 

[HomebrewPadawan]

I just found this resource while trolling around, thought I would add it. It has many options for helping you with your brewing, but specifically the "Pitching Rate Calculator" can be used the same way as I described in the article!

the site is:

http://yeastcalc.co/

enjoy!

 

[Puddlethumper]

I'm just getting started washing yeast but I have bookmarked this thread for future reference. I don't have enough experience at this to offer anything like an intelligent critique, but it does seem to follow logically. My sense of it is that you are on to a workable formula. Will continue to follow this thread. Thanks for your work!

 

[HomebrewPadawan]

Just an update: It has worked well for me for the last few years.

Cheers to beers...especially homebrewed ones!

 

[HomebrewPadawan]

Oh yeah, also bought a stir plate over a year ago...highly recommend if you have the $50-100 or the DYI itch.

 

[Gavin C]

You lost me at step one.

Rinsing yeast without specialist lab gear is just not a useful endeavor.

Save slurry. Simple and effective if you're going the route of harvesting form a fermentor after fermentation is completed.

 

[hockeybrewer]

+1 on Gavin. Don't waste time washing, your just making it look nice and washing away viable yeast cells.

 

[RM-MN]

I wonder if anyone has used this guide, haha. I got zero feedback on it...probably because it is such a looooooong post!

Just an update: It has worked well for me for the last few years.

Cheers to beers...especially homebrewed ones!

If you believe the yeast viability drop as calculated by Mr. Malty you need to look this article over as it shows a much lower viability drop if the yeast is properly stored and if the yeast isn't properly stored, you should just throw it out and quit brewing.

http://www.woodlandbrew.com/2012/12/refrigeration-effects-on-yeast-viability.html

 

[HomebrewPadawan]

If you believe the yeast viability drop as calculated by Mr. Malty you need to look this article over as it shows a much lower viability drop if the yeast is properly stored and if the yeast isn't properly stored, you should just throw it out and quit brewing.

http://www.woodlandbrew.com/2012/12/refrigeration-effects-on-yeast-viability.html

Nice article, I also agree with it.
No scientific data on my part but I feel that mr.malty accelerates the viability drop too fast as well; I know older samples start up fine. I have always been concerned about the contamination/mutation of the stored yeast, although I only keep a particular strain at most 5-6 brews before getting a fresh pitch, and have not ran into a contamination problem that I could detect yet.
I always make a starter out of my stored yeast, cold crash, calculate how many cells I have in the bottom of the flask, decant most the liquid, swirl, and then pitch the calculated correct amount...so far so good.

 

[HomebrewPadawan]

You lost me at step one.

Rinsing yeast without specialist lab gear is just not a useful endeavor.

Save slurry. Simple and effective if you're going the route of harvesting form a fermentor after fermentation is completed.

I see what you're saying for sure, I certainly don't have any specialist lab gear...unless you count a pH meter and a stir plate, haha.

I try not to rinse it much out of the fermenter, but when I drain my 6 gallon carboy of all the good fermented beer there is usually not much to swirl up the healthy yeast and separate from the trub. So at that point I'll add maybe a 1/2 to 1 gallon of boiled, cooled, water and that'll help separate the yeast from the trub. That's what I'll end up storing and consider rinsed.

How do you go about it?

 

[Gavin C]

• Rack beer to keg
  
• Pour trub from FV into sanitized mason jars
  
• Cap loosely, label and refrigerate
  
• After a day or two cinch the lids tight.
  
• Use slurry as is fresh or make starter depending on age of yeast and projected viability of the slurry later on.

Saved Slurry


*I no longer harvest yeast in this manner prefering to overbuild starters and save a never ending supply of yeast this way. My starter methods are outlined in the link below*

 

[SpecialGreg]

Question... say i got a 1600ml starter and dont want to pitch all the liquid. If i decant it in the fridge wont the yeast build up a protein wall when placed in the fridge because of the temperature dropping?

 

[HomebrewPadawan]

Question... say i got a 1600ml starter and dont want to pitch all the liquid. If i decant it in the fridge wont the yeast build up a protein wall when placed in the fridge because of the temperature dropping?

I'm no scientist, but in my experience; if you cold crash the starter for a couple of days and then decant the liquid (leaving a little to swirl up the yeast), let the yeast warm to your beers pitching temp and then pitch...I haven't seen any ill effects to this process.

Anyone who knows more about this specifically can feel free to chime in whenever they come across this thread, I would love to hear more about it.

 

[HomebrewPadawan]

*I no longer harvest yeast in this manner prefering to overbuild starters and save a never ending supply of yeast this way. My starter methods are outlined in the link below*

Great write-up GavinC, I also like to employ the overbuild yeast starter method whenever I get a new strain of yeast.

 

[Stillraining]

You lost me at step one.

Rinsing yeast without specialist lab gear is just not a useful endeavor.

Save slurry. Simple and effective if you're going the route of harvesting form a fermentor after fermentation is completed.

HA!...well what do you know! ..Finally something I ignored all the "Expert advice and videos" about on yeast washing, and just did my own way out of laziness is correct for once!!

FWIW: this is 100% ( Less what sticks to side and bottom of bucket when pouring out) of all trub slurry from my last 5.5 gal batch of porter and I dump almost 100% of my BK into my fermentator everything but maybe 1 cup of thick hop particles..... this is a quart jar.

 

[Gavin C]

HA!...well what do you know! ..Finally something I ignored all the "Expert advice and videos" about on yeast washing, and just did my own way out of laziness is correct for once!!

FWIW: this is 100% ( Less what sticks to side and bottom of bucket when pouring out) of all trub slurry from my last 5.5 gal batch of porter and I dump almost 100% of my BK into my fermentator everything but maybe 1 cup of thick hop particles..... this is a quart jar.

I wouldn't store it like that. I'm not a fan of the head-space. I like to eliminate variables like that when possible.

 

[Stillraining]

I wouldn't store it like that. I'm not a fan of the head-space. I like to eliminate variables like that when possible.

LOL...I almost added to my post at the time..."Ya! Ya! I know too much head space" but didn't do it........go figure..

FWIW its going in a batch this week end so its not in there long.. I may only pitch half of it though so I will take heed and reduce the jar if that is indeed the case....Thanks Gavin.

 

[SpecialGreg]

Nonetheless still no answer to my question

 

[d3track]

Question... say i got a 1600ml starter and dont want to pitch all the liquid. If i decant it in the fridge wont the yeast build up a protein wall when placed in the fridge because of the temperature dropping?

I chill and decant all my starters, no problems. I think the fridge chills slow enough that the yeast don't go into shock the way they would if you just dumped it into a bucket of ice water.

 

[thaefathan]

I just started collecting some quart jars of 1.080 wort, then canning (boiling to sanitize) them to save for future starters. That way I don't get any DME flavors in my beers, and I can pitch the whole thing when its active and there isn't a big lag phase in the fermenter. I think ideally it would be nice to get a group together to mash some wort just for starters, get like 12 jars and boil them all at once, just cause doing one or two at a time is kind of annoying.

At my LHBS 3lbs of DME costs $14, which is about $2.33 per 2L starter. Using 2 row I think I can make 2L of 1.040 wort for about $0.79.
Sometimes I like to try and convince myself that brewing is saving me money.

 

[IslandLizard]

I just started collecting some quart jars of 1.080 wort, then canning (boiling to sanitize) them to save for future starters. That way I don't get any DME flavors in my beers, and I can pitch the whole thing when its active and there isn't a big lag phase in the fermenter. I think ideally it would be nice to get a group together to mash some wort just for starters, get like 12 jars and boil them all at once, just cause doing one or two at a time is kind of annoying.

At my LHBS 3lbs of DME costs $14, which is about $2.33 per 2L starter. Using 2 row I think I can make 2L of 1.040 wort for about $0.79.
Sometimes I like to try and convince myself that brewing is saving me money.

Starter beer doesn't taste great because it's oxidized, it's not due to DME. Now I've never heard anyone reporting their beer didn't taste great because they pitched a few liters of starter beer with the yeast into their wort. So it must go mostly undetected, which is good, but still surprising to me. Maybe in a good Alt Beer or Kolsch you could taste it. Or light lagers.

If you want to store wort for any length of time, it needs to be properly pressure canned (sterilized), or frozen. Now if it were frozen I'd probably boil and chill it again just in case anything got in there.

I've made starter wort from plain 2-row, as well as from leftover runnings and it works great. To store it, I prepare 1.070 wort and only boil it for about 15-20 minutes. After chilling a bit, 40-44oz of the still hot wort goes into 48oz plastic cottage cheese tubs. After cooling down overnight, they go in the freezer at 0°F. The lids seal very well, but it's not sanitary, hence the reboil before use, along with a proper dilution to 1.035.