Mr Malty and Bottle Harvesting of Yeast

I am in the process of again harvesting some yeast from a bottle conditioned Ale and am unsure about the volume of actual yeast slurry I need for a 6 US gallon batch which will have an OG of only 1035. Have looked at Mr Malty and still unsure. Previously I have just pitched the 2 litre starter and it has been successful but I want to do it according to what is recommended rather than what appears to have been ok previously.

The calculator has 3 tabs labelled - Liquid Yeast , Dry Yeast and Repitched from Slurry

The yeast that I have grown (from one 375ml bottle of ale) in flasks via multiple step up stages still appears short of the figures the Mr Malty Calculator indicates as the recommended quantity.

Assuming I am going to have a 23 litre (6 gallons US) volume of wort at an SG of 1.035 and temperature of 22°C (71°F) and I have finished the step up of the starter 30 July 2011.
Can the calculator tell me an actual recommended volume of yeast (slurry only - not spent wort) from this cultivation method that I should pitch? Do I use the Repitched from Slurry tab for my calculation? I tried this tab and set the concentration slider to about 4 (nearly full right) and set the Non-Yeast % Slider to around 5%. This indicated the recommended yeast volume was 43ml. Am I on the right track?
Can anyone walk me through the process if I have it all wrong.

bump

El_caro, I have been working with slants and came across the same problem. How do you know how much yeast you have.... well I used two references to base my numbers. The first one and by far the best reading on yeast propagation and maintenance is the maltose falcon web site. They give you concentration of yeast in a solution of wort (if stepped up properly under sterile conditions) prepared in different ways. I made a spread sheet from this and the numbers there match MrMalty exactly (in terms of final cells required and starter volume).

The second was mrmalty repitch from slurry tab as my yeast was yery clean i set non yeast % to minimum and density i put low as it had not compacted much and use that to guestimate volume(note i put the starter in the fridge for 48 hrs before i calculated the slurry quantity to get max yeast to foc out of suspension) both of these gave me the confidence to pitch the yeast.

I assume being a good South Aussie your using coopers pale. The coopers web site has a HB forum with some good info on culturing from bottles.

Clem
Clem

Clementine said:

El_caro, I have been working with slants and came across the same problem. How do you know how much yeast you have.... well I used two references to base my numbers. The first one and by far the best reading on yeast propagation and maintenance is the maltose falcon web site. They give you concentration of yeast in a solution of wort (if stepped up properly under sterile conditions) prepared in different ways. I made a spread sheet from this and the numbers there match MrMalty exactly (in terms of final cells required and starter volume).

The second was mrmalty repitch from slurry tab as my yeast was yery clean i set non yeast % to minimum and density i put low as it had not compacted much and use that to guestimate volume(note i put the starter in the fridge for 48 hrs before i calculated the slurry quantity to get max yeast to foc out of suspension) both of these gave me the confidence to pitch the yeast.

I assume being a good South Aussie your using coopers pale. The coopers web site has a HB forum with some good info on culturing from bottles.

Clem
Clem

Click to expand...

Thanks Clem
Yes Coopers Pale Ale it is this time. Have bottle harvested on several occassions before quite easily but never really sure on the technical side of yeast quantity. I just pitched the results of a 2 litre starter and away she went.
I really would like to know how many ml of fresh yeast I should be pitching though by using the calculator.
I will take your advice and look at the maltose falcon web site.

Cheers

Here is the link to the site

http://www.maltosefalcons.com/tech/yeast-propagation-and-maintenance-principles-and-practices

Clementine said:

Here is the link to the site

http://www.maltosefalcons.com/tech/yeast-propagation-and-maintenance-principles-and-practices

Click to expand...

Good reading!
Thanks Clem

As far as I understand it, if you use mr malty re pitching from slurry calculator. Use the defalt settings and that should give you the right thickness if you have crash cooled your starter and allowed the yeast to compact. There is a function that helps you estimate yeast health by entering the date the yeast was harvested, In your case it would be 0 days.
As far as Mr Malty is concerned, if you want to pitch the whole starter without crash cooling you would have to use guess work.

bob3000 said:

As far as I understand it, if you use mr malty re pitching from slurry calculator. Use the defalt settings and that should give you the right thickness if you have crash cooled your starter and allowed the yeast to compact. There is a function that helps you estimate yeast health by entering the date the yeast was harvested, In your case it would be 0 days.
As far as Mr Malty is concerned, if you want to pitch the whole starter without crash cooling you would have to use guess work.

Click to expand...

Hi Bob, Those slider setting are what confuses me a little - where to set them for a cold crashed starter is the big question I have.

I was wondering whether the default setting of around 15% non yeast is not a little high and the yeast concentration default perhaps a little low for a well crashed starter.

If you listen to Jamil's podcast "Brewstrong" he talks about it. I can't remember which one it is, might be yeast washing or re pitching?
Anyway he says for most cases you shouldn't touch the slider settings as they are designed for the standard yeast washing process, crash cooling and all. Just adjust the harvest date for viability and do the o.g and all that. So that's from the horses mouth.

I would be interested to find out if anyone has an accurate way to estimate non-yeast percentage and concentration.