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-   -   MrMalty Caculator - Are the vials to volume ratios linear? (http://www.homebrewtalk.com/f163/mrmalty-caculator-vials-volume-ratios-linear-373781/)

jtkratzer 12-12-2012 06:42 PM

MrMalty Caculator - Are the vials to volume ratios linear?
 
I'm brewing batches making 10 gallons of finished beer into kegs. I haven't done anything that I'd consider high gravity since starting all grain and I want to confirm that I can tweak the numbers on MrMalty.

Results indicate I need 3 vials of yeast in a 2.4 L starter for 11 gallons of wort. If I double the starter size to 5 liters, can I cut the number of packs in half? I know 1.5 packs of yeast is not a quantity one could buy. Just checking if the math works and the yeast behave that way.

Liquid yeast seems to be the highest priced ingredient and I don't mind making starters. I've never used more than single vial of yeast for any batch of beer. I usually make starters or used washed yeast with a starter.

I'm thinking if I do a 4L starter with a single vial, that puts me at roughly 400 billion cells per the pitching rate section of MrMalty. If I decant, and add another 2-4L, that should get me plenty of yeast.

Preference is to do one starter, but if I have to step it up for a beer this size, no worries.

Yes? No? Maybe?

jkendal 12-12-2012 06:49 PM

Quote:

Originally Posted by jtkratzer (Post 4675894)
I'm thinking if I do a 4L starter with a single vial, that puts me at roughly 400 billion cells per the pitching rate section of MrMalty. If I decant, and add another 2-4L, that should get me plenty of yeast.

Preference is to do one starter, but if I have to step it up for a beer this size, no worries.

Yes? No? Maybe?

I have a 10-gallon system. When I use liquid yeast I start with a 2L starter and then the next evening step it up to 4L. I get excellent results every time.

WoodlandBrew 12-12-2012 06:52 PM

Yeast is expensive. That's why I went to saving slurries and counting cells.

Slide the "growth rate" slider to see how big the recommended starter is with less vials.

As for the volume of the starter, it isn't linear. As the inoculation rate drops (less vials to more wort) the growth also drops. I would figure out how much wort 100 billion cells (one vial) can support and pitch into that. Wait a day and add the remainder of the wort. See here for details:
http://woodlandbrew.blogspot.com/201...-starters.html

If you are interested in cell counts check this:
http://woodlandbrew.blogspot.com/201...viability.html

Golddiggie 12-12-2012 06:56 PM

If you want to save vials of yeast (or not buy so many) check into making stepped starters. Yeastcalc.com will be of more help, there, than mr. malty. With two, or three, starter steps, you can get the same (or more) yeast than you would with a huge starter. Talking about each step being under 2-3L in size, compared with over 20L as a single step.

jtkratzer 12-12-2012 07:02 PM

I have a 2L flask and just ordered a 5L flask as the 2L seems to be too small to do a single step for a 10 gallon batch of 1.075 or higher wort.

I'll check out the links, but I'm looking for simple without having to buy multiple yeast vials. When washing yeast, I measure the volume of the yeast slurry for pitching into a starter, but that's about it. I have two kids under 3 and I just want to make beer. I'd rather avoid spending 2 weeks on the starter with multiple steps of growth, chill, decant, add wort, repeat.

jtkratzer 12-12-2012 07:07 PM

Quote:

Originally Posted by WoodlandBrew (Post 4675928)
Yeast is expensive. That's why I went to saving slurries and counting cells.

Slide the "growth rate" slider to see how big the recommended starter is with less vials.

As for the volume of the starter, it isn't linear. As the inoculation rate drops (less vials to more wort) the growth also drops. I would figure out how much wort 100 billion cells (one vial) can support and pitch into that. Wait a day and add the remainder of the wort. See here for details:
http://woodlandbrew.blogspot.com/201...-starters.html

If you are interested in cell counts check this:
http://woodlandbrew.blogspot.com/201...viability.html

The stepped calculator is pretty sweet. A 4 liter starter of 1.040 wort followed up by a 1.5 liter step puts me at my target total cell count.

Golddiggie 12-12-2012 07:08 PM

Longest I've ever had a 3 step starter schedule take was 6-7 days. That was with older yeast too (over 4-6 months old), with a stirplate. If you don't have a stirplate get or make one ASAP. Not only will your starters finish faster, but you'll be able to make smaller ones too.

I typically use either my 2L or 3L flask (on the stirplate). I have yet to need to use my 5L flask by doing at least two steps.

BTW, I get Wyeast packs from the LHBS (Jasper's) for <$7/pack. Some stores sell them for about $8/pack. Online, you'll spend a lot on shipping charges. You can also wash/harvest yeast after it's been used. OR, get a single pack/vial, make a starter from it, gather that up and freeze it. Then just thaw out the vial you're going to use and make another starter to get the cell count up.. Serious savings to be had that way. I did that part of a starter I reserved. Stepped it up in my 2L flask a couple of times and froze 12 50ml vials of it. :rockin: I should have enough yeast (of that strain) to easily go until they offer it again (Wyeast 1882-PC). Thinking about getting a couple of other strains and doing the same thing. Especially ones I can't easily get locally.

zeg 12-12-2012 07:10 PM

In general, no, it's not linear in either number of yeast packs or starter volume. If you hold these in constant ratio, then yes, it should be linear (so if you double the volume and pitch twice as much yeast, you will end up with twice as many cells).

There's an optimal pitching rate for maximum growth factor, which is one good target. However, since it's generally cheaper to increase the starter size (or do multiple steps), the financially optimal rate might differ. I recommend playing with yeastcalc.com to get a feel for this.

There's also a good discussion of this (with plots!) in the book "Yeast."

zeg 12-12-2012 07:13 PM

Quote:

Originally Posted by jtkratzer (Post 4675993)
The stepped calculator is pretty sweet. A 4 liter starter of 1.040 wort followed up by a 1.5 liter step puts me at my target total cell count.

I'd suggest playing with the numbers to do two similarly-sized steps or a smaller size in the first step and a larger in the second. The calculator is likely to be more accurate for modest growth factors. It is also likely to be gentler on the yeast.

Golddiggie 12-12-2012 07:28 PM

I typically make a smaller starter for the first step, then the second (or third) so that it will still fit in the flask.

Also, yeast production date impacts the size of your starter. If the calculation tool doesn't have provisions for that, don't use it. Also be sure to enter that information into the tool. Otherwise, you won't get an accurate assessment.


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