anyone know what the default OG that’s used for the mr.malty (Mrmalty.com) and yeast calculator (http://www.yeastcalc.com/indexupdate.html) starter calculators use?
im thinking they use 1.035 or 1.040, but not sure. i learned recently its more beneficial to use around 1.030 for creating healthier yeast, and want to make sure i’m calculating the amount produced correctly for my starters.
thanks
When I go to yeastcalc.com the default in the OG for the calculator that tells me how much DME to use is 1.037 so I would assume that is the same defualt they are using. But you might be able to email the site admin and find out for sure.
ok good idea. do you target lower OG for your starter than 1.037? im not sure the cell count difference between 1.030 and 1.037, but imagine it could result in under pitching if using 1.030 and stepping up.
I am not all that exacting, I use the 10ml:1gram formula which results in pretty dead on 1.037. That being said I am not brewing lagers at this time which seems you be your personal golden fleece and it may be more important given your larger cell count needs. The ‘minor’ cell count discrepancies in my 1.5 liter starter are going to be magnified in your 6 l
understood. i emailed mr.malty to see what they use for OG. i will report back when i get an answer…i suspect your are right in that both calculators are similar.
Jamil assumes a 1.040 starter wort, but realistically the difference between the estimated and actual cell counts are going to be greater than the effect of using 1.032 or 1.037 or 1.040 wort.
so i found a calculator that lets you modify your OG…uses either braukaiser or chris white growth formulation (you choose). http://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/
braukaiser is much more conservative with growth calculations vs. chris white. seems yeast calc is closer to braukaiser.
What Sean said. They’re all (MM,YC,BF) estimates and if you do actual cel counts there are pretty large discrepancies.
Even the 100bl. cel per pack count is an estimated figure…I’m sure each batch is checked, but not each pack.
That said, I do like Brewersfriend. It gives you more data sets to choose from so you can find something that works well for you.
i agree. im using the braukaiser growth model as its the most conservative, and if i do anything, i’d rather over pitch.
The difference is because Jamil’s model for yeas grow assumes fairly high growth rate when the starting pitch rate is high and low growth when the starting pitch rate is low.
In my experiments I found different behavior and documented it here: Estimating yeast growth | Braukaiser
If you look at the 1st step, you are getting more growth with the braukaiser model. Then for the 2nd step you are getting less growth b/c you are starting out with many more cells per gram gram on extract.
Kai
Exactly. I’d rather go with conservative since I will never know exactly how many cells I start with from the vial or pack, or exactly how many are produced in the starter. I like brewersfriend especially because of the ability to manipulate the OG of the starter wort.
I recently had my yeast samples counted. I grow up the yeast and decant into sanitized White Labs vials. When I am done the vial look identical to the vials at the LHBS…so I thought. The cell count showed that my sample wasn’t nearly as dense as fresh WL vial…only about 50 billion cells or roughly half. I usually use YeastCalc but I found out that my results were only about 75% of the calculators growth rate.
The other thing is that I believe those calculators use 100 billion cells as the starting point. I think that White Labs say their vial contain on average 100 billion cells but can be as low as 80 billion and as high as 120 billion. A 20% difference at the very beginning would have a huge impact, especially with stepped starters, on your final cell count. Now…how much does it really matter? I have been making award winning beer using “flawed” cell counts and underpitching healthy yeast.
The MrMalty calculator is sensitive to the initial cell density in ways that I have not observed. I observed that for stirred starters the new growth is mainly dependent on the amount of extract in the wort regardless of the cell density. At least up to a certain density. Because of that starting out with 80 or 100 Billion cells doesn’t make much of a difference if you will be growing 300 B regardless of the starting cell count.
Kai
That sounds about right. My experience has been that slurries compact relatively quickly to about 2-2.5 billion/mL, but after that it can take several weeks at 4°C to reach the fully compacted count of 3.5-4 billion/mL.
I think you mean 2-2.5 billion/ml, 3.5-4 billion/ml.
Oh sure, the PhD weighs in. :
You’re right, of course. Thanks!
I’m having a long brew day - LOTS of time on my hands, but not enough time to tackle any of the projects that need to happen around here. I’ve been able to read the forum a lot more today