# Mr Malty Pitching Rate Calculator



## cubbie (1/12/09)

Hi I have never been able to completely work out how to use the Mr Malty Pitching Rate Calculator in terms of my yeast starter techniques. Essentially I only make one size starter so Mr Malty is irrelevant, but I am interested in how my starters compare.


Firstly I make a starter for all my yeast, the only time I do not make a starter is when I pitch directly onto the yeast cake of a just racked beer. Anyway I use Wyeast as my preferred yeast. (have used pro-culture just the once).

My starters are made in a 2.5-3L flagon (can't remember the exact volume). If I am using a new Wyeast pack I will added 1.5-2L of wort (10g/100mL DME-Water) to make the starter. When I pitch the starter I reserve some yeast for the next - as pretty much everyone does. Now I used to reserve the yeast in stubbies but for a while now have been using the small test tubes as in this thread http://www.aussiehomebrewer.com/forum//ind...\&st=0

These test tubes take up a lot less room in the fridge. Once the yeast has settled out in the test tube, only the bottom 1/4 - 1/3 is yeast slurry. Now this is a very small amount of yeast. I will use 1 test tube to make my next starter.

I have never noticed the effects of under pitching in my beers (although it may be be there), but recently altered my yeast starter regime to account for the small initial yeast count. I will build the starter up over three to four phases starting at about 10g/100ml - adding say 30g/600ml, 130g/1300ml total 2L starter ( I used to pitch the test tube directly into a 1.5-2l starter). I try to add the next phase when I think the yeast has gone through each growth stage.

Anyway my question is how do I correctly calculate my yeast count and how could I use Mr Malty to calculate it?


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## Screwtop (1/12/09)

cubbie said:


> Hi I have never been able to completely work out how to use the Mr Malty Pitching Rate Calculator in terms of my yeast starter techniques. Essentially I only make one size starter so Mr Malty is irrelevant, but I am interested in how my starters compare.
> 
> 
> Firstly I make a starter for all my yeast, the only time I do not make a starter is when I pitch directly onto the yeast cake of a just racked beer. Anyway I use Wyeast as my preferred yeast. (have used pro-culture just the once).
> ...



There will be many opinions, here's mine. Measure the amount of slurry in your test tube (cos this is what it is, not pure yeast) and step it using MrMalty's Calculator, click the tab for Repitching From Slurry, I leave the slides on the default 4.5 or half way for Thick/Thin Slurry and 25% non yeast percentage. I set the harvest date to the date that I stored part of the original starter in the bottle in my fridge. The wort gravity is set to 1.040 for 10:1 waterME starter and the volume set to 2 litres. The volume of of slurry will then be calculated. If you have enough for a 2L starter then make one 2L starter, if not make a convenient sized starter to suit the volume of slurry you have available and step it up to the required pitching starter volume as per the MrMalty Calculator for the volume and gravity of your wort.

Thats my 2c 

Cheers and happy brewing,

Screwy


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## cubbie (1/12/09)

Cheers Screwy,

If I understand you correctly I should be starting with about a 500ml for a 1.040 starter and stepping up, considering I think those test tubes hold about 20ml.
What would you recommend as the correct process to step up a starter? As I have described above? 

I think they discuss this in How to Brew which I have at home.


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## Screwtop (1/12/09)

cubbie said:


> Cheers Screwy,
> 
> If I understand you correctly I should be starting with about a 500ml for a 1.040 starter and stepping up, considering I think those test tubes hold about 20ml.
> What would you recommend as the correct process to step up a starter? As I have described above?
> ...



That checks out. Starters............well it's all available......search or have a look at Mr Malty's Yeast Pitching Rates and How To Make Proper Starters here Linky

Nothing new in brewing, all this stuff has been done, just need to find it. 

Cheers,

Screwy


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## mauriceatron (4/12/09)

The best thing about that pitching rate calculator is that you can experiment with it. The worst thing is that I think it confuses some people with all those options.

For vials or dry yeast, just measure it out. For pitching from slurry, I tend to assume around 90% viability and that just gets me there for that kind of brew that I do.

Most importantly, don't be scared by the numbers, just experiment and lean with what you do and you'll find out that the pitching rate calculator is like nothing else in brewing: just another guide but like all good things, a guide to be followed or adjusted depending on you as the brewer.


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## Thirsty Boy (5/12/09)

You can manipulate that calculator quite a bit - the way I make starters I sometimes have to.

I usually start from a slant - I don't pinch a little yeast, I use the whole slant. I tip in 15ml of sterile wort, shake and wait - this gets tipped into 250ml of wort.

Here's where I have to make an assumption - slant to 250ml seems to give me about the same amount of yeast as I get out of a smackpack. So I can go from there.

But if you are using smaller amounts, like splitting a pack or tube... you just change the viability level. Say you have a month old smackpack, you work out the viability from the date, then if you split it, you divide the viability... so if the whole pack was at 75% and you split it into 3 tubes... then you plug 25% viability into the calculator and go from there.

It wont play with starter sizes smaller than 1.0L which is a bugger.. but what you do is set it to "Ale", 1.040 as gravity, your starter type (simple, stirrer etc) and the viability you worked out - and adjust the volume up or down till you see it change from a starter size of 1.0 to 1.1. Take note of the number of cells... this is how many cells you will get from a 1.0L starter with your "portion" of a smackpack. You can then pug this number expressed as a percentage of 100billion cells (which is basically a fresh smackpack or vial) back into the viability box (it will take numbers great than 100%) to work out your next step.

I tend to adjust the step up starter size till I end up with 100billion cells... worth - make that starter as my first step, then go up from there as though I actually had a perfectly fresh pack. I could make a larger step up starter... but whether I do or not depends on how small a portion if yeast I have. I wouldn't like to put anything less than 25billion cells into a starter much bigger than 1L.

Thats how I do it anyway... might be all up the putt, but it seems to be working for me.

TB


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## jiesu (28/4/10)

So I am after a little bit of clarification on how to use this tool. 
I am about to put down a 1.050 (roughly)25litre american amber ale from some washed yeast off the trub from my last batch. 

I am having some issue working out exactly what the yeast Viability is. So I took my yeast off of my trub on Friday last week so according to mr Malty that would make my 
yeast about 86% viability. Now do I put into Mr malty the specifications of my starter wort to work out how much of the washed yeast slurry I pitch to make that starter? 
Ie in the Malty calculator do i make the variables 1040, 2 litres, 86%

Which will mean I need about 15billion cells or 7ml of slurry
(based off assumptions {developed from reading this thread and also the link to proper yeast pitching rates on maltys site}
that my washed yeast will be approximatly 2.5ml on the liquid to thickness scale and only 5% non yeast material because it has been washed)

Now If I am to create a starter out of this yeast will that change my viability up to around the 95% rate? because The yeast have been made active again through a
fermentation?



How do I work out exactly how many yeast cells have been created in the two litre wort? Acroding to mr malty for a 1.050 25L @ 95% I need 231 billion cells. Does my starter even need to be 
2 litres? If for my starter I need 15 billion cells and my wort I need 231 million how to I work out how many Litres Of wort I need to grow 216Billion Yeast cells to make up the difference. what am i missing here. 


Cheers


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## Frank (28/4/10)

Do you need to make a starter?
I would direct pitch the slurry if I had enough on hand. Depends on your parameters, approx 150ml of yeast slurry would be required.
If you check the Wyeast website, I am pretty sure they indicate how much a starter will multiply your yeast numbers.


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## jiesu (28/4/10)

Boston said:


> Do you need to make a starter?
> I would direct pitch the slurry if I had enough on hand. Depends on your parameters, approx 150ml of yeast slurry would be required.
> If you check the Wyeast website, I am pretty sure they indicate how much a starter will multiply your yeast numbers.



I have no idea. Most literature refers to a "yeast slurry" however mine is closer to a yeast cake under about 200 mls of cloudy water.
I imagine the best approach is to pour 80% of the water of the yeast cake then stir the remainder of the yeast up so it is all suspended.


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## razz (28/4/10)

DT, if you check the Wyeast site the calculator works a bit differently than the JZ calculator. From memory, it more easily cals the amount of yeast slurry, especially if repitching or doing two step starters. The Yeast Labs site calculator also talks about yeast slurry densities which possibly is what your after.
PS. Sorry, that should be the White Labs site, not Yeast Labs.


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## Wolfy (28/4/10)

*daft templar* if you have harvested the yeast slurry within the last week (or two at the most) there is no need to make a starter, just pitch the correct amount using the 'yeast slurry' option on the calculator.

When entering details in the calculator you put the properties of the wort you'll pitch into not the starter you make, so if you are going to make a 25L 1.050OG American Amber, those are the details you put in.
When I re-pitch from slurry I wash the yeast a few times to remove any unwanted gunk and to clean it up a bit (anything that sinks quickly or floats gets thrown out, I just keep the milky/yeasty middle layer) then I let it settle out and pitch just the thick slurry from the bottom.
With those parameters you're looking at about 60-100ml of the slurry pitched into your 25L wort (which is probably only 1/2 or 1/3 of what you saved from the previous batch).

*cubbie*, in regard to how much yeast to pitch (with or without using a calculator), Ray Daniels suggests that "_1 million yeast cells per degree Plato per milliliter of wort_" is what is used "on a commercial scale" for "_good brewing practice_". (degrees Plato is equal to specific gravity divided by for for this equation).
For a 5 gallon batch that's 200-400 billion yeast cells - which is pretty much the number that the calculator gives. However he also suggests a "_homebrew pitching rate and consider it to be the absolute minimum that should be pitched_" which is _"10 to 20 billion yeast cells per 5 gallon batch"_.

The table in Daniel's book lists "_Typical values for different yeast/starter types:
Dry yeast ~ 20 billion cells/g =10-20g Dry yeast
Slurry ~ 1.5 billion/ml = 100-200ml Slurry
Liquid ~ 2-5 billion/pack**
Slant/Starter ~ 20-50 million/ml = 1-4.5L starter_"

As you can see using dry yeast or re-pitching slurry is the easiest way to achieve the number of cells suggested, as even a liquid yeast pack has many less cells than suggested.

_**Daniels book was published in 1996/2000 and I'm not sure if Wyeast have changed packaging since then, because JZ suggests 100billion cells is what he found in each pack.
According to JZ a Wyeast pack pitched into a 1L starter gives about 150billion cells, and into a 2L starter gives 200billion cells, a smack pack into 1L then 4L starter gives 400billon cells._

Like *Thirsty Boy* I often step up starters from slants, when I do, I assume that the starter has the same number of cells by the time it gets to 1-2L as if I was growing it from a smack-pack.
But even then the calculator caters for all options, including what type of starter you are making, so it's well worth the effort to get to know the various options as it can help provide a good estimate of how much yeast you need each batch.


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## jiesu (28/4/10)

razz said:


> DT, if you check the Wyeast site the calculator works a bit differently than the JZ calculator. From memory, it more easily cals the amount of yeast slurry, especially if repitching or doing two step starters. The Yeast Labs site calculator also talks about yeast slurry densities which possibly is what your after.
> PS. Sorry, that should be the White Labs site, not Yeast Labs.



I had a look at the white labs site and couldn't find any pitching calculators. Are you sure thats the site you meant?




Wolfy said:


> *daft templar* if you have harvested the yeast slurry within the last week (or two at the most) there is no need to make a starter, just pitch the correct amount using the 'yeast slurry' option on the calculator.
> 
> When entering details in the calculator you put the properties of the wort you'll pitch into not the starter you make, so if you are going to make a 25L 1.050OG American Amber, those are the details you put in.
> When I re-pitch from slurry I wash the yeast a few times to remove any unwanted gunk and to clean it up a bit (anything that sinks quickly or floats gets thrown out, I just keep the milky/yeasty middle layer) then I let it settle out and pitch just the thick slurry from the bottom.
> With those parameters you're looking at about 60-100ml of the slurry pitched into your 25L wort (which is probably only 1/2 or 1/3 of what you saved from the previous batch).



How do you determine if you need to make a starter or not? I assumed that the whole point was to grow a healthy population of yeast enough to chew through whatever amount you are fermenting? If so then wouldn't it be completely dependant on the amount of yeast you happened to pick up from the previous batch?
I did three batches at once, two of which I first mixed the slurry and yeast together and put into long necks to settle out. The third I put into a two litre container. I then proceded to wash them about 4 times each However along the way I forgot to sanitise one of the jars and therefor had to throw that sample out which meant that, that paricular strain was left with much smaller sample then the others because i had to wash that strain from the dregs of the previous washing jar.
So i the end I have three strains with three different quantities of yeast in them. I could try to make them all of the same consistency but I am guessing that the first sample (2litre slurry) will end up being approx 80 mls the second about 50 and the third about 10mls which I guess would mean that I would need to make a starter from them? I would Also like to keep at least a small quantity of all three yeasts after I pitch them So I can use them in future brews. 


So If i put the details for a 25L 1050 @ 86% wort into malty I get about 80mls which if I want to save a little for next time will mean I need to make a starter for all three of my varieties. 
So how do i determine how many yeast cells will be created from the starter If I decided to only use say 10ml of slurry at any particular quantity at the usual 1040 starter?


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## Wolfy (29/4/10)

daft templar said:


> How do you determine if you need to make a starter or not? I assumed that the whole point was to grow a healthy population of yeast enough to chew through whatever amount you are fermenting? If so then wouldn't it be completely dependant on the amount of yeast you happened to pick up from the previous batch?
> ...
> So If i put the details for a 25L 1050 @ 86% wort into malty I get about 80mls which if I want to save a little for next time will mean I need to make a starter for all three of my varieties.
> So how do i determine how many yeast cells will be created from the starter If I decided to only use say 10ml of slurry at any particular quantity at the usual 1040 starter?


Yes, but if you think of your first batch as simply a 25L starter then you should always have ample yeast to use when you re-pitch.
I usually find I have about 1L trub/yeast left in the fermenter, after aggressive washing there is usually at least 250ml left, and - if used within a week - that is usually more than adequate for repitching into any volume/OG wort.

If I have only a small amount of yeast to start with (a slant or 10ml slurry) then I treat it as a liquid starter (as *Thirsty Boy* also said he does) and work on the assumption that because I 'step up' in small steps (usually 4-6x each step) the volume of starter calculated will be the same as if I used a smack-pack to start (I usually take 3-4 steps to get to the 1.5 to 2L starter rather than just 1 if using a smack-pack).


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## Screwtop (29/4/10)

Wolfy said:


> Yes, but if you think of your first batch as simply a 25L starter then you should always have ample yeast to use when you re-pitch.
> I usually find I have about 1L trub/yeast left in the fermenter, after aggressive washing there is usually at least 250ml left, and - if used within a week - that is usually more than adequate for repitching into any volume/OG wort.




Yes.................but! 

If you do have an adequate volume of healthy yeast cells, suitable for the volume and gravity (not any) of wort you are pitching to.....it is always best to pitch a STARTER. This is a case of confusion AGAIN between STARTERS and STEPPING UP to reach an adequate cell count.

A STARTER is simply an active amount of fermenting wort! Two reasons for making a starter 1. To proof the yeast (make sure it is healthy). 2. To reduce lag time.

Stepping up is used to reach the required cell count. If you need to step up, yeast cells will multiply roughly 3 times in wort of a gravity around 1.040


There is a good help page associated with the Mr Malty Calculator: http://www.mrmalty.com/calc/liquid_tab.html

This is also a good read: http://brewingtechniques.com/library/backi.../kingtable.html

Hope some of this helps you get a better handle on stepping and starters daft templar

Cheers,

Screwy


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## razz (29/4/10)

razz said:


> DT, if you check the Wyeast site the calculator works a bit differently than the JZ calculator. From memory, it more easily cals the amount of yeast slurry, especially if repitching or doing two step starters. The Yeast Labs site calculator also talks about yeast slurry densities which possibly is what your after.
> PS. Sorry, that should be the White Labs site, not Yeast Labs.





http://www.wyeastlab.com/hb_pitchrates.cfm
My mistake dt, it was this page from Wyeast I was referreing to. I thought it may help you when you were talking about your washed yeast.


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## Wolfy (29/4/10)

Screwtop said:


> Yes.................but!
> 
> If you do *not *have an adequate volume of healthy yeast cells, suitable for the volume and gravity (not any) of wort you are pitching to.....it is always best to pitch a STARTER. This is a case of confusion AGAIN between STARTERS and STEPPING UP to reach an adequate cell count.
> 
> ...


May I assume you did not mean to leave out the '*not*' as I have added in bold above?

Do you have a reference for the 3x increase in yeast cells when stepping up? The link you provided indicates logarithmic growth and that the increase may be 1000x.
(I've been working on the assumption that the yeast cell count would be related to total volume and wort conditions more than anything else.)


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## jiesu (29/4/10)

Thanks for the replies I have done some more reading. 
So after using a combination of the Wyeast starter and growth calculator in combination with Mr malty and several conversions between total cell count and millions per /ml then Converting between Gallons and Litres like 8 times I have deduced the following. Provided my maths is correct which I doubt it is 

If I used approx 25mls of my slurry Into a starter of 250mls then at high krausen I pour another 1.5litres of wort into the starter I will have around 280B Cells that I can pitch to my 25Litre wort.

Does that sound correct?


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## jiesu (29/4/10)

Shit this is complicated.... Why is their not an all in one growth and And pitching rate calculator.


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## drsmurto (29/4/10)

If you have an entire yeastcake from a previous batch and its only been in the fridge for a week then i would be using a cup (250mL) of it in the next 20-25L batch (OG <1.060)

Any longer than a week and i would be doing as Screwy mentioned and proving it first by adding a cup of the slurry to a small starter, 1L would seem adequate. Wait till high krausen and pitch.

The only times i have lost a batch to an infection is when i was lazy and used yeast slurry that had been in the fridge for a month or more without making a starter. An entire yeastcake on one occasion and still the lag time was more than 48h. 

Lesson learnt. Healthy yeast makes nice beer :icon_cheers:


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