HomebrewPadawan
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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!!
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!!