Author Topic: Just ordered a stir plate  (Read 7740 times)

maxieboy

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Re: Just ordered a stir plate
« Reply #30 on: January 27, 2011, 10:06:58 am »
I'd rather step up starters from one vial. Saves cash. Check this out(from BN forum):

"You can tweak the calculator at Mr Malty to help you work out starter stepping up.

Say you want are brewing a 1.072 bock and you want 500billion cells. Thats either a 6L starter on a stirplate, or 5 fresh packs of yeast. But you can step up instead. You are going to pitch a fresh tube/smackpack into 1.0L of wort as your first step.

So what you do, is juggle the gravity and volume numbers in the calculator, till it tells you that you need a 1.01L starter - dont worry about what you are actually brewing, just muck about till it tells you what you need is 1.01L. Now look at the amount of cells it says that will be in that 1.01L starter. Remember that number. (its about 237billion cells)

OK, without changing anything else - go to the % viability input box and increase it. It will go up past 100%. Increase it till the line that says "vials or packs needed without starter" decreases to 1. It will be roughly the amount of cells you have divided by 100billion. so for our example, the percentage figure where the packs needed figure changes from 1.1 to 1.0 is 226% and it says no starter required.

so effectively you have one smackpack with 226% viability.

Go back to the start - plug in the gravity and volume of the beer you want to make - and set the viability to the percentage figure you just worked out (226%) - and now the calculator will tell you what size to make your "second" starter if you use the yeast from the first one. in this example it tells us we need a 2L starter to go from our 237billion cells to 500billion.

So you start with a fresh vial - make a 1L starter - then either decant the beer and add 2L of fresh wort to the yeast, OR assume that all the nutrient is gone, and add a further 1L of double strength wort (which when diluted with the first one = 2L of starter strength wort) - and this will give you the approximately 500billion cells you need. And your starter was never more than 2L.

Ive gone 1L - 2L - 4L and ended up with over 1000billion cells for a big batch of strong beer."

« Last Edit: January 28, 2011, 02:41:45 pm by maxieboy »
A dog can show you more honest affection with a flick of his tail than a man can gather through a lifetime of handshakes." Gene Hill

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Kaiser

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• Imperial Brewing Geek
Re: Just ordered a stir plate
« Reply #31 on: January 27, 2011, 10:48:11 am »
Ive gone 1L - 2L - 4L and ended up with over 1000billion cells for a big batch of strong beer

Maxieboy,

I'd be careful in using Jamil's calculator in a way that it may not have been designed for. Mostly because Jamil's experiments may have made certain assumptions.

I have been looking into yeast growth as well and some of the things that Jamil was/is seeing don't line up with what I'm seeing. For example I don't see much difference in new yeast growth per extract for different initial cell concentrations. At least up to a point.

What I'm seeing is that on a stir plate you get about 1.1 - 1.4 B new cells for every gram of extract in your wort. What this means is that your 6 l of 1.040 wort can grow 660 - 840 B new cells. To what extent that can be optimized by stepping up, I.e. splitting the 6l into steps, I don't know. I suspect that if you need to let fermentation finish in each of these steps to decant the starter wort you may loose some efficiency since more of the available energy needs to be spent to maintain the yeast during those dormant phases.

Kai

richardt

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Re: Just ordered a stir plate
« Reply #32 on: January 27, 2011, 11:58:49 am »
Practically speaking, I'd rather have a yeast pitching calculator that tells me to pitch one vial or smack pack of yeast into 1 liter of "x" SG wort, aerate on a stir plate or with aquarium pump/tubing for "y" days, to get "z" cells/ml.

Based on the calculated or planned OG of my beer, it would then advise me whether or not I needed to do further step ups for the starter and provide details how to do such with regards to starter wort volume, starter wort gravity, starter size, number of steps, etc.  Very few of us have a hemocytometer.

The counts aren't practical, in my view, but telling me that I should have an adequate number of cells in a 600 ml yeast cake in my cold-crashed 2 liter yeast starter after pitching a smack pack into 1.040 starter wort and giving it 72 hours to grow and 48 hours to chill would be more useful info for me.

Kaiser

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Re: Just ordered a stir plate
« Reply #33 on: January 27, 2011, 12:07:00 pm »
Practically speaking, I'd rather have a yeast pitching calculator that tells me to pitch one vial or smack pack of yeast into 1 liter of "x" SG wort, aerate on a stir plate or with aquarium pump/tubing for "y" days, to get "z" cells/ml.

Yes, that’s what I was thinking as well. It always bothered me that Jamil would assume that I’d be starting with more than 1 vial/pack of yeast. And from my experience, if you start with that many cells (50-100B) you can pitch directly into the final starter volume if you have a large enough starter vessel.

Quote
Very few of us have a hemocytometer.

Most of us have scales and I do think that we can weigh the sediment and use that to estimate the actual cell count. Especially in starters where you tend to have less trub.

Kai

maxieboy

• Senior Brewmaster
• Posts: 1155
• Mid MI
Re: Just ordered a stir plate
« Reply #34 on: January 27, 2011, 02:04:27 pm »
Ive gone 1L - 2L - 4L and ended up with over 1000billion cells for a big batch of strong beer

Maxieboy,

I'd be careful in using Jamil's calculator in a way that it may not have been designed for. Mostly because Jamil's experiments may have made certain assumptions.

I have been looking into yeast growth as well and some of the things that Jamil was/is seeing don't line up with what I'm seeing. For example I don't see much difference in new yeast growth per extract for different initial cell concentrations. At least up to a point.

What I'm seeing is that on a stir plate you get about 1.1 - 1.4 B new cells for every gram of extract in your wort. What this means is that your 6 l of 1.040 wort can grow 660 - 840 B new cells. To what extent that can be optimized by stepping up, I.e. splitting the 6l into steps, I don't know. I suspect that if you need to let fermentation finish in each of these steps to decant the starter wort you may loose some efficiency since more of the available energy needs to be spent to maintain the yeast during those dormant phases.

Kai

I should have put quotes around the whole thing. The one thousand billion cells statement is the BN poster's. JZ did weigh in later in the thread and thought that the process was sound.

I am FAR from an expert on this subject. I just got into stirplate starters and was looking for info on starters and stepping them up in order to save a little money while assuring proper pitch rates as well. I'll probably never get in to counting yeast cells and I think this method gets me as close as I need to be. I am always looking to simplify and streamline my process and this fits the bill for me.

The calculator does allow you to build your starter from one pack to your starter in one step but in most cases you're going to need a vessel larger than 2L(for 10g batches). The advantage in the process above is that you can do a 2 step starter in the one 2L vessel(stirplated) and get aprrox.450- 500B cells which is what I need for the majority of my 10g batches.

Wow, is it hard to type and edit a response when everything doesn't fit into the space allotted or what?! Yecch.
« Last Edit: January 27, 2011, 07:01:53 pm by maxieboy »
A dog can show you more honest affection with a flick of his tail than a man can gather through a lifetime of handshakes." Gene Hill

[47.7, 310.8] AR

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Hokerer

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Re: Just ordered a stir plate
« Reply #35 on: January 27, 2011, 02:34:59 pm »
Wow, is it hard to type and edit a response when everything doesn't fit into the space allotted or what?! Yecch.

Yayyyy!!!  It's not just me.  When I'm typing a post and go beyond the limits of the text entry box, things go absolutely nuts.
Joe

Pawtucket Patriot

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Re: Just ordered a stir plate
« Reply #36 on: January 27, 2011, 07:19:23 pm »
Update: I got home from work and took a look at my stirring starter.  There's definitely more activity evident at this point.  It's been fermenting for about 24 hours.  I turned up the speed a bit and there is more foam forming at the surface.  Looks like I'm growing yeast!
Matt Schwandt | Minneapolis, MN
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