Splitting a starter

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SouthernGorilla

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Is it possible to split a starter so that both halves are equally potent? I'm about to start a small experiment with four one-gallon test batches and two different yeasts. I thought I ordered four packs of yeast for the starters, but I only ordered two. Can I whip up an oversize starter of each yeast and then cut them in half accurately? Could I split the contents of the packets while dry? Or am I better off finding an LHBS that carries the same yeast so I can buy a couple more packets?
 
If you're really dealing with dry yeast you probably have plenty enough to not need to build a starter. A single pack of 11.5 g yeast can handle a typical 5-gallon batch unless you're talking very high gravity. You've got less wort than that. So if you want to pitch normal quantities, you can split the packet(s) while dry. You'll need a decent scale to measure accurately, or just eyeball it if you're going to split into 2 or 4 equal pitches. Since it's an experiment you might want to go to the extra effort of getting the pitching rates accurately equal. You could also overpitch, but it might take away from the intended character of the beer.
 
The experiment is comparing lager vs warm fermentation with the same yeast and recipe. I'm using two different yeasts just to provide more data. The plan is to make up four gallons of brew, split it into four gallon jugs, add each yeast to two jugs, put one jug of each yeast in an SOF chiller, and leave the others at room temperature. Then keep track of each individual fermentation to see the differences in how they ferment. And then to compare the final products of each to see just exactly what difference lagering makes. I haven't found any research on this subject. Would half a pack of dry yeast be sufficient to run a lager? I've always read that lagers require a good starter. And for consistency I want all every batch to have the same starting conditions. So if I do need a starter for the lagers I also want one for the warm batches. But if I can simply split the packets in half and rehydrate them then I'll go that route.
 
SouthernGorilla said:
The experiment is comparing lager vs warm fermentation with the same yeast and recipe. I'm using two different yeasts just to provide more data. The plan is to make up four gallons of brew, split it into four gallon jugs, add each yeast to two jugs, put one jug of each yeast in an SOF chiller, and leave the others at room temperature. Then keep track of each individual fermentation to see the differences in how they ferment. And then to compare the final products of each to see just exactly what difference lagering makes. I haven't found any research on this subject. Would half a pack of dry yeast be sufficient to run a lager? I've always read that lagers require a good starter. And for consistency I want all every batch to have the same starting conditions. So if I do need a starter for the lagers I also want one for the warm batches. But if I can simply split the packets in half and rehydrate them then I'll go that route.
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I love experimenting. I've got a 5-way lager experiment going now myself. 6 gallons split into 5 different lager strains: WLP820, 833, 838, 860 and Wy2633.

The yeast pitching rate calculator on MrMalty.com says that you'd need about 5g of dry yeast for 1 gal of 1.050 wort (75% viability). You can plug in your conditions there (http://www.mrmalty.com/calc/calc.html). If you're packs are 11.5g, the you've likely got enough.

As for your experiment, consider this: If you want to compare methods that would show even more difference you could compare pitching cold (e.g. Narziss-like ~44F) and fermenting cold vs pitching warm and fermenting warm. The current experiment you're planning is pitching warm and fermenting cold vs pitching warm and fermenting warm. Since the main flavor components are set early in fermentation and you're pitching warm in both cases, you might not see much difference. A classic debate is on whether it's OK to warm pitch lagers. Also consider whether you'll be doing a d-rest. Usually cold pitching (Narziss-like) will avoid the need.
 
Hex23 said:
I love experimenting. I've got a 5-way lager experiment going now myself. 6 gallons split into 5 different lager strains: WLP820, 833, 838, 860 and Wy2633.

The yeast pitching rate calculator on MrMalty.com says that you'd need about 5g of dry yeast for 1 gal of 1.050 wort (75% viability). You can plug in your conditions there (http://www.mrmalty.com/calc/calc.html). If you're packs are 11.5g, the you've likely got enough.

As for your experiment, consider this: If you want to compare methods that would show even more difference you could compare pitching cold (e.g. Narziss-like ~44F) and fermenting cold vs pitching warm and fermenting warm. The current experiment you're planning is pitching warm and fermenting cold vs pitching warm and fermenting warm. Since the main flavor components are set early in fermentation and you're pitching warm in both cases, you might not see much difference. A classic debate is on whether it's OK to warm pitch lagers. Also consider whether you'll be doing a d-rest. Usually cold pitching (Narziss-like) will avoid the need.
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I plan to chill the lager before pitching because I do want to create as much difference as possible. I should have mentioned that in the outline I gave above. I like the warm vs cold pitch idea. I might test that at a later date.

Turns out I have the 5g yeast packs. Simply splitting them would have me underpitching by half. Maybe run a starter, let the yeast settle out, then split the cake in half?

I'm a huge fan of firsthand experimentation. Like most hobbies, brewing is full of myth and hearsay. Future experiments I plan include; tap water vs distilled vs "spring", thin vs thick decoction vs infusion, and then (maybe) more detailed experiments on lager temperature and duration. I just like having a good side-by-side comparison of things to really show how different aspects of the process affect the final product.
 
That's what I'm asking, whether there's any technique for accurately splitting a starter. That's the title of the thread.
 
SouthernGorilla said:
That's what I'm asking, whether there's any technique for accurately splitting a starter. That's the title of the thread.
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Yes, when everything is completely in suspension simply pour into graduated vessels equal amounts:)
 
SouthernGorilla said:
So about 48 hours after pitching the starter? I've never used a starter so I have no idea how long it might take to peak.
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Yes, should be done by then, you should see a slight krausen ring.
 
Not to complicate things, but ...

Usually when I make a starter for a lager, I end up decanting the spent starter beer because the volume of the starter is relatively large compared to the main batch. And that will take longer than 48 hours, because you're supposed to let it ferment out, fully flocculate, then decant. However depending on the specs on your starter, you might not have to do that, which brings me to my other point. If you care to pitch close to the proper amount, you're going to need to calculate a proper volume and method for your starter. Typical starter calculators (like on Mr Malty) won't tell you about building starters from dry yeast, because it's not common. You'll have to do some math based on the cell counts of dry vs liquid yeast packets. Since the calculators are based on experiments with liquid yeast, it won't be exact, but probably close enough.
 
SouthernGorilla said:
I'm a huge fan of firsthand experimentation. Like most hobbies, brewing is full of myth and hearsay. Future experiments I plan include; tap water vs distilled vs "spring", thin vs thick decoction vs infusion, and then (maybe) more detailed experiments on lager temperature and duration. I just like having a good side-by-side comparison of things to really show how different aspects of the process affect the final product.
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Totally agree. I've found it filled with things that are theoretically true, or directionally true, but with difference in outcome so small that it's almost irrelevant.
 
Hex23 said:
Not to complicate things, but ...
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You know it's time to run for cover when somebody says that. :)

So now I need to plan more thoroughly. I need to know what OG I plan and what temperature I want to use for the lager. I'll calculate the starter off that and use the same starter for the warm fermentation. That will probably mean overpitching the warm batches. What are the consequences of that?
 
As long as the 4 beers aren't way overpitched or underpitched, I wouldn't worry too much. Giving them the same pitch amount is probably more important for the experiment - only change one variable at a time. One should pitch higher amounts for colder temps (a main reason lagers require higher pitches than ales), but I wouldn't sweat it too much. I'm probably over-complicating things. But I would pay attention to how large your starter is and consider not pitching it all into the wort, but instead decanting. A general rule of thumb is no greater than 5% volume.

What's I've heard about overpitching is that it will generally result in less overall "beer character". Yeast make byproducts that make beer what it is. Yeast will make less of these byproducts with larger pitches.
 
So run the starter until it finishes and the yeast settle. Then decant most of the liquid and split the cake as needed. Simple enough.

I'm not terribly worried about the character of the final product since this is just an experiment. But I still want to do what I can to ensure it turns out right.
 
Yes, if your total starter will be more than 5% of 4 gallons (possibly not the case here), then it's recommended to decant. If you need to decant, it will be easier if you also save enough liquid to swirl the yeast back out of the sludge/cake.
 
Since you're needing to roughly double your cell count, a 1 liter starter is probably good enough. That wouldn't be too much more than 5% volume, so you you probably don't need to decant. Make sure you have enough head-space in your starter vessel. My experience with putting dry yeast into a starter is that they'll take off pretty quickly and vigorously.
 
Of course, now the problem is equipment. I need four one-liter starters and I only have one two-liter flask. So what I might do is split each yeast pack in half and make four individual starters in quart mason jars. I'll mix the starter "wort" in a gallon jug for uniformity, split it between the four jars, then pitch the yeast into each. That way I have as much consistency as possible between the starters.

Thanks for the help.
 
SouthernGorilla said:
Of course, now the problem is equipment. I need four one-liter starters and I only have one two-liter flask. So what I might do is split each yeast pack in half and make four individual starters in quart mason jars. I'll mix the starter "wort" in a gallon jug for uniformity, split it between the four jars, then pitch the yeast into each. That way I have as much consistency as possible between the starters.

Thanks for the help.
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BTW, I was actually calculating a single 1L starter for the whole 4 gallons. 0.25 liters into 1 gallon is about 6.6%. What I did was not a very accurate way of calculating the volume because I just calculated the volume it would take to double a 100B cells to 200B, with a stir-plate. Since you are starting with more than 100B cells, it might not be that accurate, but probably close enough.

You could do what you stated here, and it might be a better idea if you don't have a stir-plate, but you'll definitely want to decant that. 1L into 1 gallon is over 25% volume. If you've ever tasted starter beer, you'll know why you should decant large starter volumes. Some say that the beer will clean it up, but in a small gravity light lager, I doubt that.
 
No way to make a single starter for all of it since I'm using two yeasts. I can either split the dry packs and make two small starters from each yeast or I can make a single starter from each pack and then split the cakes after they settle.
 
SouthernGorilla said:
No way to make a single starter for all of it since I'm using two yeasts. I can either split the dry packs and make two small starters from each yeast or I can make a single starter from each pack and then split the cakes after they settle.
Click to expand...

Good point. I missed that fact.
Be sure to report back with your results. I'm curious.
 

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