Is there much growth difference between step and batch starters? For example, difference between a 4 qt starter or a 2 qt starter and adding 2 qts two days later
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In theory the yeast multiply until they run out of food. But that process is best accomplished with the least amount of stress, which occurs when you go too large in one step. Whether going directly to one gallon is stressful would depend on the number of cells pitched. From a slurry of lively harvested yeast, i see no problem going to a gallon straight away. From a slant culture - now that would be a problem.
Check out www.yeastcalc.com
I can’t speak to adding 2 quarts later. If I step up a starter I’ll chill and decant first.
Dave
Yeast cell density does make a difference in growth, but at this size i doubt it would be noticeable. Actually, 4 gallons probably is not large enough to decrease cell growth. The Yeast book has a table showing density and growth.
Can’t get on that site with my shmart phone, sadly
“Freedom is temporary unless you are also Brave!” - Patriot
In theory, you’ll get a little more growth out of the large single starter since the pitching rate is lower. Are these stirred or aerated starters? If not, oxygen will be the limiting factor either way. I doubt you’ll see a practical difference no matter what - unless you’re doing cell counts, the variations in pitching rate are probably ±20% or more regardless.
So risk reward is null… sounds like single batch will be easier and less prone to infection, so if there’s not real gain from steps, I’ll be doing batch from now on.
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According to Wyeast, you would get more yeast from the 2 step starter (28 million cells/ml vs. about 20).
http://www.wyeastlab.com/hb_pitchrate.cfm
The effect seems to be more pronounced with a stir plate… without one the results were 18 vs 16.
I’m sure someone who knows a lot more about yeast than me can explain the theory behind this. I do multi-step starters for big batches and have done cell counts on them and can say that the results are in the ballpark.
So if you have the space, there is no need to chill and decant? I never thought of that. For example, I have a 2.5 gallon bucket with a little over a gallon of starter wort spinning on a stir plate right now (Wyeast 2352). Rather than chilling and decanting before pitching another gallon of starter wort, I can just boil up then chill the new wort and add it. Then chill and decant prior to the pitch into the batch this weekend. It saves a step!
There’s alcohol. Not that 2% is going to be awful for the yeast, but I’d much rather have them in a 0.2% solution.
The advantage of stepping if you need a large pitch is that one can achieve an optimal growth rate if the starter pitch rate is within certain limits (also discussed in the book “Yeast”). Within that pitch rate the yeast will grow at their highest rate while maintaining a healthy growth environment.
The disadvantage of stepping is vessel size limitations (for some, myself included), time, and risk of infection. If sanitation is at the forefront of your brewing operations, infection should not be a problem. Stepping does require crashing and decanting to remove the spent wort leaving only the healthy slurry, and a significant increase in the volume is usually a good idea, 10 times is recommended but I’ve had good success with much smaller second steps.
Making a starter is as much about increasing the cell count as it is about creating the healthiest pitch possible. Starting with a large volume such as 4 liters will grow yeast, just not as much as a 2 liter starter, assuming one vial or smack-pack is used.
I’ve not had a sanitation issue yet. I have brewed with US05 just dumped in, hydrated, proofed, then Wyeast smaks just dumped in, started in 1 qt, 2 qt, 4 qt, and recently learned about 2 qt steps. I’ve done steps but didn’t crash and decant. I may try that next and see what I get. With this thread I was fishing for opinion, experience and numbers. It sounds like I can increase growth by maybe 10% with steps. Stir plates are the big jump.
Stir plates are on my next upgrade wish list. That will be next fall along with adding two ORANGE Gott mash tuns so I can do two fives at a time.
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I’m pretty sure that’s backwards… Using the Wyeast calculator a 2 L starter will grow 150-250 billion cells, and a 4 L will grow 240-370 billion. MrMalty/YeastCalc says 110-210/190-330, and Kai’s suggested equation 300/610 (stir plate).
As Kai has pointed out recently, the assumption that increasing pitching rate will increase growth is counterintuitive, and not borne out by experimental data.
In your example no, not much difference. But your example also is not a “stepped” starter, the step refers to increasing the amount of the starter, say from 1 to 3 liters or 2 to 4 liters etc. This will get you the substantial difference in growth that stepped starters are intended to create. I will at least try to double the previous volume when doing stepped starters.
If you can get near your pitch rate with one starter, then definitely do that.
I make starters for 2 reasons, to grow an appropriate amount of yeast to pitch. Or to “wake” the yeast up and pitch an active, ready to go starter for a quick fermentation.
I’m not following you here. He’s proposing a step from two quarts to four quarts. Sort of like your two liters to four liters. How is that not a stepped starter?
When I step up starters I typically double the volume as he is proposing, which is also what you seem to be recommending.
HUH??? He is merely not decanting, making 2- two qt starters, not a 2-qt starter then a 4 qt starter.
I follow you now.
He’s doing steps in that he’s first pitching ~100 billion cells in 2 liters and then pitching the resulting starter (with more yeast) in 2 liters. He’s just not “stepping up” the size, so there’s less advantage than you’d get otherwise.
According to the Wyeast calc and Mr malty, you do get more new cell growth from 2 liters of starter wort when you pitch 2 packs versus 1. Hence the steps result in more overall yeast than 2 seperate 2-liter starters (or one 4l starter).
Oy. …
I pitch one activator into two quarts, then in two days I add two quarts. Is that stepped?
I am going to try crash/decant before adding the second two quarts. Would that not be stepped?
In theory other seems no different other the first method other than getting rid of spent wort and alcohol. But I have been totally lost before
“Freedom is temporary unless you are also Brave!” - Patriot
IMO it is stepped. Repo is saying that you’ll get better growth if you added four quarts to the two quarts (or decanting and then adding the four quarts) so that you’re stepping up the size of the starter.
I don’t always decant and frequently do what you are proposing to do. It works just fine for me.
Either way you will get growth. Doubling the amount of wort for the second step will give you better growth.
Do it whichever way works best for you.