Yeast starter calculators- OG not an issue?
- Thread starter guldalian
- Start date
Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:
Jeepaholic
Well-Known Member
Not really, yeast only reproduce while they have access to oxygen. That us why you use a stir plate on a starter. Once the oxygen is gone it doesn't matter how much food is left they will just eat not reproduce.
Jeepaholic
Well-Known Member
It will make less yeast. Because in a starter you are either stirring or shaking constantly there will be less food for them to use to make more yeast. There is a huge difference in yeast production between making a starter and making beer. When making beer they go into an anaerobic state in starters they stay in an aerobic state.
The CO2 produced by the yeast is pushing out of the container- no new oxygen is getting back in. The reason we use a stir plate is to keep the yeast in suspension so they'll continue to reproduce.
I target my starters at 1.030, for no other reason than I've seen the acceptable range given as 1.020 - 1.040 and decided to split the difference.
In every case the starter worked.
Jeepaholic
Well-Known Member
Very true except I have read that some air does make it in the flask even with the co2 pushing out. I have been planning to get a O2 meter for use in my wort. It would be fun to see what the level of O2 is in a starter.
Looks like the calculator just uses the gravity to calculate the amount of DME required and assumes that the gravity of the starter is within reasonable limits.
-a.
-a.
PaulVikingAles
Active Member
- Joined
- Oct 23, 2012
- Messages
- 39
- Reaction score
- 2
You can only grow a fixed amount of yeast in a fixed size starter. You will not grow enough yeast in a 1.25L starter if it required a 1.5L. If you are not using a stir plate then you will grow less and the only way to make up some of that is I use a larger starter and good aeration. Are you brewing 5 gallons? Our minimum starter size is a 2L starter on a stir plate for 5 gallons and goes up for higher gravity beers. It has never failed us.
it seems like it may be more a function of how much food (sugar) is available to the yeast. read the first post in this excellent blog.
http://woodlandbrew.blogspot.com/
sethlovex
Well-Known Member
- Joined
- Jan 25, 2013
- Messages
- 189
- Reaction score
- 15
What is your source for this information? Is there some study or experiment you are quoting? I feel like if this were true you could just put an airlock on your starter instead of a foam stopper or sanitized foil
A starter's not much different that a regular 5 gallon batch. You can aerate your batch, then throw an airlock on, and there's enough dissolved O2 and in in the headspace to finish fermentation.
Some O2 does diffuse in using a loose covering of foil. How much depends really depends on the velocity of the CO2 through the neck of the container. A vigorous fermentation with a narrow-necked container will allow less oxygen in (Chico strain in boiling flask). Conversely, a less vigorous fermentation with a wider necked container will allow more oxygen to diffuse in (most Belgians in a straight-walled beaker). BUT, we don't really care how much is exchanged because there's enough to finish fermenting a batch of 1.040 anyway (edit: assuming you aerated), so most people just opt for the smaller opening because it's easier to keep contaminants out.
Since we don't care about oxidation of the starter wort, there's no harm in using the stir plate with the foil.
Back on topic. Yes. More food, more cells. Assuming oxygen and space are not limiting factors. Think of a stir plate as increasing the available space the yeast have by keeping them from floc'ing into a pile at the bottom.
Oversimplification perhaps, but it's a decent memory aid.
I'm sure it'll finish fine. Just maybe not in 24 hours like a stir plate would.
PaulVikingAles
Active Member
- Joined
- Oct 23, 2012
- Messages
- 39
- Reaction score
- 2
I might not made myself clear on my post. The amount of food is important for yeast growth but there are other factors that are just as important. If a 1.5L starter is required then pitching into a 1.25L starter wort will never give you enough yeast unless the 1.5L starter was calculated with shaking as your aeration but you actually put your 1.25L starter on a stir plate. You will then grow enough yeast. Stepping up is the best way to go and that is to grow your 1.25L starter and repitch only a portion of the yeast slurry. If you pitch the entire slurry into another 1.25L starter you will not grow more yeast, maybe a little. Your yeast will begin to ferment the beer and there will be minimal yeast growth. The only way to grow more yeast is to pitch small amounts of the slurry into the same size starter or to pitch the entire slurry into larger volume starters and continue increasing until you reach the cell count you need. You can read more on this in Yeast: A practical guide to beer fermentation written by Christ White with Jamil Zainasheff. You do not typically need to produce more than what a 2L starter, aerated on a stir plate, will grow for 5 gallon batches.
Hmm. Ok. I used 151g dme ehich was req'd for 1.5L which is 1.25L instead. I pitched the 2 vials of yeast and shook it every half hour for about 3 hrs until i went to bed. I may try and pitch some of the slurry in a new starter. Or start over. My beer is going to have an og of 1.085 so I want to get this right
No problem. I don't know how old your vials were, but I'll assume 80% viability and that they were Wyeast packs at 100b cells ea.
Using YeastCalc:
Enter "5" for 'Batch Volume [Gallons]'
Enter "1.085" for 'Original Gravity [SG]'
Notice you need 290b cells total. That's not very much.
Uncheck 'Calculate Viability from Date' and enter "80" for 'Viability%', or enter a date
Enter "200" for 'Initial Cell Count [billions]'
Select 'Intermittent Shaking' for 'Method of Aeration'
Enter "1.5" for 'Starter Volume [Liters]
Notice you will have made 135b new cells for a total of 295b. This is fine.
In this case, you could have avoided the second vial by making a 3.3L starter instead (in a gallon jug).
Or, use the quick and dirty 1.5 b/g DME estimate to come up with 226b new cells, putting you at 387b total cells.
Either way, you're fine. Keep shaking it for 48 hours total, then cold crash it for brew day.
Estimating yeast cell count is a very rough process. Getting within a factor of 2 on your pitch rate is considered good enough. Because cell growth is exponential, you don't start getting odd flavors until past a factor of 2.
Using YeastCalc:
Enter "5" for 'Batch Volume [Gallons]'
Enter "1.085" for 'Original Gravity [SG]'
Notice you need 290b cells total. That's not very much.
Uncheck 'Calculate Viability from Date' and enter "80" for 'Viability%', or enter a date
Enter "200" for 'Initial Cell Count [billions]'
Select 'Intermittent Shaking' for 'Method of Aeration'
Enter "1.5" for 'Starter Volume [Liters]
Notice you will have made 135b new cells for a total of 295b. This is fine.
In this case, you could have avoided the second vial by making a 3.3L starter instead (in a gallon jug).
Or, use the quick and dirty 1.5 b/g DME estimate to come up with 226b new cells, putting you at 387b total cells.
Either way, you're fine. Keep shaking it for 48 hours total, then cold crash it for brew day.
Estimating yeast cell count is a very rough process. Getting within a factor of 2 on your pitch rate is considered good enough. Because cell growth is exponential, you don't start getting odd flavors until past a factor of 2.
Last thing. What yeast strain was this? You might have been able to do this much cheaper with dry yeast packs.
wow thanks! I didn't know about that calculator. I like it. Only question I have is if the starter volume is how much you boil? or is it the final volume in the starter. In my case I boiled 1.5 ened up with 1.25 in flask. Just for future reference. Thanks
The calculator assumes you use every drop of what you boiled. None was thrown away.
Stir or swirl your starter wort before pouring it so it's a homogeneous solution. That what there's the same percentage of fermentables in what you keep and what you toss.
But personally I'd never toss starter. Throw it in a sanitized jar and put it in the fridge. Chances are you'll need it in two weeks.
Stir or swirl your starter wort before pouring it so it's a homogeneous solution. That what there's the same percentage of fermentables in what you keep and what you toss.
But personally I'd never toss starter. Throw it in a sanitized jar and put it in the fridge. Chances are you'll need it in two weeks.
WLP001. That's the same as Wyeast 1056. And the same as Safale US-05.
Next time, just pick up Safale US-05 packets. 250b cells in a packet. No starter needed. At my LHBS, White Labs is $7.75 for 75-150b cells, Wyeast is $6.50 for 100b cells, and Safale is $3.75 for 250b cells.
Quality is the same. Liquid just provides more available strains with a shorter shelf life (6 mos vs 2 yrs).
Next time, just pick up Safale US-05 packets. 250b cells in a packet. No starter needed. At my LHBS, White Labs is $7.75 for 75-150b cells, Wyeast is $6.50 for 100b cells, and Safale is $3.75 for 250b cells.
Quality is the same. Liquid just provides more available strains with a shorter shelf life (6 mos vs 2 yrs).
sethlovex
Well-Known Member
- Joined
- Jan 25, 2013
- Messages
- 189
- Reaction score
- 15
So the northern brewer website has a yeast calc PDF and the 2nd step up is way smaller than the first, I just don't get the logic. 1 L starter, decant and pitch into .5 L starter? I thought you ere supposed to increase the volume at least 4x..
You have a 1.4 gal/hr boiloff rate on your stove? That's pretty darn high.
You just need to maintain the boil, not be roiling like crazy. We're not trying to caramelize the sugars or increase the gravity, just sanitize the water and DME by denaturing bacterium.
Feel free to boil starter wort with the lid on. We usually leave the lid off of AG wort we plan to drink because we're trying to boil off DMS which leads to a corn taste. But since we don't care about the taste of the starter wort, just its fermentability, feel free to lid it up. Just be aware that it's easier to boil over that way, so a few drops of FermCap-S goes a long way.
2nd step doesn't have to be larger than the first. You'll just get diminishing returns each additional step assuming the same amount of wort each time.
The idea being that as the cell count continues to grow, more and more of the sugars are used to sustain the existing cells and less to split off new cells.
1L into 0.5 L sounds a bit too small for this application.
sethlovex
Well-Known Member
- Joined
- Jan 25, 2013
- Messages
- 189
- Reaction score
- 15
thadius856 said:
Check this link:
http://www.northernbrewer.com/documentation/YeastPitchingRates.pdf
They say 338 billion cells...am I missing something?
No, you read that right.
YeastCalc puts it at 128b new cells for the 1st step, 34b new cells for the second step. That seems about right to me. And that's with a stir plate. MrMalty is usually with a few % of YeastCalc.
At a generous 1.5 b/g DME, that stepping should give 225b new cells.
As I said before, because of the exponential growth pattern of yeast, getting within a factor of 2 is good enough to make great beer.
YeastCalc puts it at 128b new cells for the 1st step, 34b new cells for the second step. That seems about right to me. And that's with a stir plate. MrMalty is usually with a few % of YeastCalc.
At a generous 1.5 b/g DME, that stepping should give 225b new cells.
As I said before, because of the exponential growth pattern of yeast, getting within a factor of 2 is good enough to make great beer.
Similar threads
