How large of a flask should I get for a yeast starter?

I want to start making starters but I need to get the flask. How large of a flask should I get? Is 1L big enough or should I definitely get a 2L flask?
My beers are usually not too big, I'd say typically between 1.050 and 1.080.

thanks

I'd get at the very least a 2L flask.

I regularly make 2 liter starters for 6 gallon batches, using two half-gallon growlers.

i'd also recommend growlers for starters.

why spend money on a flask when you can get a 1/2 gallon glass container full of beer for a lot cheaper? granted, you can't boil in a growler....

otherwise, i'd go at least 2 liters. i bought a 1 liter and wish I bought a 3. but then my 1L broke and I haven't missed it since I started using growlers.

1L is too small. 2L is a good size for most beers. I end up using 1 gal jugs or growlers for high gravity beers, though. They aren't as convenient as the Pyrex Ehrlenmeyer flasks, though, as someone previously mentioned.

Thanks for the responses. The only reason I don't like the idea of using a growler is because you can't see the yeast activity through the brown glass. Maybe that doesn't matter? For those of you that use growlers do you just wait until you see bubbling through the airlock?

thanks

I use 1L flasks because they were half the price of 2L flasks at the time I bought them and I'm a cheap bastard.

Pitching 600-800mL of liquid, I still notice a huge decrease in lag time over just dumping a vial, so I'm not that fussed about it. Someday I'll probably step up to a 2L flask but it's one of those "when it's convenient" things.

bubbling through the airlock?

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You don't want to use an airlock. A sanitized piece of aluminum foil is easier, cheaper, and allows O2 to enter the flask.

And def get at least 2L. 1L is fine if you're doing small 5-6g batches, but if you ever want to do bigger batches/beers and/or lagers...you'll be glad you went bigger.

Beavdowg said:

Thanks for the responses. The only reason I don't like the idea of using a growler is because you can't see the yeast activity through the brown glass. Maybe that doesn't matter? For those of you that use growlers do you just wait until you see bubbling through the airlock?

thanks

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Don't use an airlock. Just put tin foil over the top of the growler/jug/flask. You want to let out the CO2 and let in the O2.

And yes, the brown glass is a pain, but you can usually see krausen if you hold a light behind it. Glass jugs are more convenient from that perspective (I like the thick-walled cider jugs best). Alternatively, you can always pull a sample and taste for sweetness (i.e. lack of fermentation) or check its gravity.

i don't use an airlock. i use a piece of tin foil. i might grab a few foam stoppers next time i'm at the LBS and try those out.

i usually just make my starter 24-36 hours ahead of time. night before brew day i put it in the fridge, then morning of brew day I take it out of the fridge. then I decant, add a bit of fresh wort right before pitching, swirl it around and dump it in.

Do we really get O2 in a container that has actively fermenting beer inside? It's giving off CO2 and there is a positive pressure...i.e. gas is flowing out, not in. And it's not mixing at the mouth of the container and somehow getting in that way either (in my estimation, I can be convinced otherwise).

Just look at what the stir-plate manufacturers say. They say we're not using a stir plate to get O2 in the solution, just to keep the yeast in suspension and drive off CO2.

I know the popular opinion is foil over airlock in a starter but I just don't think the rationale for doing so makes sense. I really don't think it makes much difference, I don't think O2 isn't getting in either way.

EDIT: IMO, 1L flask is too small even if you use a stirplate. 2L is what I consider minimum size with a stirplate. 1 gal. without.

Diffusion of O2 works across the pressure gradient. Remember, that by using foil you aren't really restricting the flow of gas out of the flask. The pressure difference is essentially nothing in this case, so there is little to prevent oxygen from diffusing into the vessel.

Stir plates get O2 into your beer because they constantly move the fermenting wort to the surface where O2 diffusion can occur from the air into the liquid. Even if the concentration of O2 is less inside the vessel than atmospheric, remember that only a little is needed by the yeast and there is a constant supply.

My $.02

Charlos,

You might have the best avatar of any one on here! Well, I'm also quite fond of the 2 German Octoberfest girls going at it! Can't remember who that is. Anyway, could you get your avatar into your gallery so we can see it larger?

You can get clear growlers.



I think Northern Brewer has them (although I got mine from microbreweries).

Diffusion of O2 works across the pressure gradient. Remember, that by using foil you aren't really restricting the flow of gas out of the flask. The pressure difference is essentially nothing in this case, so there is little to prevent oxygen from diffusing into the vessel.

Stir plates get O2 into your beer because they constantly move the fermenting wort to the surface where O2 diffusion can occur from the air into the liquid. Even if the concentration of O2 is less inside the vessel than atmospheric, remember that only a little is needed by the yeast and there is a constant supply.

My $.02

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Yea, I bought into all that at first when you (or flyangler) made the "Don't use an airlock on your starter" thread. But the stirplate folks say it doesn't get O2 in your beer. And if you look at the yeast cell counts for stirplated starters vs non...it's not that much of an increase (seems like it would be more if we were constantly feeding O2). I realize that the diffusion works over the pressure gradient...but it just seems that inside that container(and especially at the surface of the beer)...no O2. And certainly not enough if there is no stirplate action (making the foil moot on non-stir plated starters).

Hmmmm....I have portable O2 monitors at work.

SpanishCastleAle said:

Hmmmm....I have portable O2 monitors at work.

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That would be the definitive test -- do it! :rockin:

SpanishCastleAle said:

Yea, I bought into all that at first when you (or flyangler) made the "Don't use an airlock on your starter" thread. But the stirplate folks say it doesn't get O2 in your beer. And if you look at the yeast cell counts for stirplated starters vs non...it's not that much of an increase (seems like it would be more if we were constantly feeding O2). I realize that the diffusion works over the pressure gradient...but it just seems that inside that container(and especially at the surface of the beer)...no O2. And certainly not enough if there is no stirplate action (making the foil moot on non-stir plated starters).

Hmmmm....I have portable O2 monitors at work.

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Figure 1. Effect of aeration on yeast cell number. 500 ml of BrewTek Superwort was pitched with a saturated 10 ml superstarter culture of BrewTek yeast and incubated at room temperature (75 °F) for two days. Cultures were either shaken 3-6 times a day, aerated with BrewTek aeration system for several minutes (foam permitting) 3-6 times a day, or continuously stirred on a magnetic stir plate. Yeast cell concentration was determined on the BrewTek hemacytometer. Traditional starter (with airlock) were taken from numbers published by Ray Daniels in HBD #1746 using Wyeast packet as inoculum.



Extracted from http://www.maltosefalcons.com/tech/yeast-propagation-and-maintenance-principles-and-practices
Written by Dr. M.B. Raines

FlyGuy said:

That would be the definitive test -- do it! :rockin:

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And dry ice and some badass glassware. Might take a few days to get it all done discreetly.

EDIT: Sudbuster those numbers are different than when I plug stuff into the Mr Malty Yeast Pitch Rate calculator. Simple example is 1 yeast pack plus ~1.1L starter. Stirplate yields ~240B and a simple starter (no agitation or anything) yields ~150B. It is a bigger difference than I implied but nowhere near the numbers you posted.

Split the difference. Buy a 1.5 liter jug of Carlo Rossi in the flavor of your choice. Consume. Clean. Make starter.

goose_on_fire said:

I use 1L flasks because they were half the price of 2L flasks at the time I bought them and I'm a cheap bastard.

Pitching 600-800mL of liquid, I still notice a huge decrease in lag time over just dumping a vial, so I'm not that fussed about it. Someday I'll probably step up to a 2L flask but it's one of those "when it's convenient" things.

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I'm a cheap bastard too. I got the 1L and regret it. It's better than nothing until I spring the green stuff to fix my mistake and get a 2L.....And I only make session beers!

FWIW, until I got a stirplate I used a 1 gal pickle jar. Like $6 and you get a bunch of tasty pickles.

SpanishCastleAle said:

And dry ice and some badass glassware. Might take a few days to get it all done discreetly.

EDIT: Sudbuster those numbers are different than when I plug stuff into the Mr Malty Yeast Pitch Rate calculator. Simple example is 1 yeast pack plus ~1.1L starter. Stirplate yields ~240B and a simple starter (no agitation or anything) yields ~150B. It is a bigger difference than I implied but nowhere near the numbers you posted.

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Well, yeah, that is a pretty big disparity, Hmmm, who we gonna trust, Dr. M.B. Rains or Jamil? Jeez... what a conundrum

Get a stirplate or your gonna need a huge bottle for any starters you do. If you have the stirplate, Get the 2L for most average gravity ales. You will still need a larger one for high gravity ales and all your lagers.

I've used the growlers. You can find clear ones but they are seam to be rare. Downside is you can't boil in them and you can flame the opening.

For big starters I use a 1 gallon apple juice bottle. It was about 5.00 and came with some tasty juice.

why can't you flame the opening on a growler? i have....

motobrewer said:

why can't you flame the opening on a growler? i have....

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Some times they crack from rapid changes in temp. That's what makes the flasks superior. The flasks are made of special glass that can go hot to cold very fast without breaking.

Sudbuster said:

Well, yeah, that is a pretty big disparity, Hmmm, who we gonna trust, Dr. M.B. Rains or Jamil? Jeez... what a conundrum

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Yea, I thought about that Sudbuster. Tough to argue with a real scientist. I went back and looked over JZ's Fourteen essential questions... article and in the section on stirplated starters he says:

In my tests, vigorously shaking a starter every hour resulted in approximately double the number of cells versus a non-shaken starter and a stir plate resulted in a 40% gain over a shaken starter.

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But when you use the calculator it doesn't agree (below I just changed the starter type and OG until the starter size was about the same, ~3.9L in this case. Then looked at the cell count).
Per the calculator:
1 yeast pack plus 3.97L of simple starter yields 275B cells
1 yeast pack plus 3.9L of shaken starter yields 347B cells
1 yeast pack plus 3.88L of stirplated starter yields 417B cells

Here the stirplated starter isn't even double the simple starter.

In any case, I've been sort of blindly trusting that calculator and you've given me reason to question it. So thanks for that.

I have a 1L, 2L, 4L and a 5L flask to cover everything I am doing. I use the 2L the most and at the minimum I would use that. I like the fact I can boil in it and do not have to transfer into another container.

Ive got 2L and 5L Erlenmeyer. I reckon the 5L is the most conventient. If I want a 4L starter I don't have the extra work of stepping up a 2L.
8L is just one step-up. And I can make a 2L in the same flask.

maida7 said:

Some times they crack from rapid changes in temp. That's what makes the flasks superior. The flasks are made of special glass that can go hot to cold very fast without breaking.

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yeahi get that. i can understand boiling in a growler, but a little flaming? i guess i'll find out when i break one, lol

i just flame lightly, i don't try to melt the glass or anything

SpanishCastleAle said:

Yea, I thought about that Sudbuster. Tough to argue with a real scientist. I went back and looked over JZ's Fourteen essential questions... article and in the section on stirplated starters he says:
But when you use the calculator it doesn't agree (below I just changed the starter type and OG until the starter size was about the same, ~3.9L in this case. Then looked at the cell count).
Per the calculator:
1 yeast pack plus 3.97L of simple starter yields 275B cells
1 yeast pack plus 3.9L of shaken starter yields 347B cells
1 yeast pack plus 3.88L of stirplated starter yields 417B cells

Here the stirplated starter isn't even double the simple starter.

In any case, I've been sort of blindly trusting that calculator and you've given me reason to question it. So thanks for that.

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I think you are manipulating the calculator to do something that it isn't meant to do. I'm not sure what variable Jamil has in the calculator that changes the concentration/ml like that. Yeast concentration per ml is what you should be focusing on instead of changing the gravity to match starter size.

For example, take an ale at 1.08 OG, 5 gallon batch at 97% viability.
This wort needs 273 billion cells. A stirplate accomplishes this with 1.52 liters and a simple start meets it at 4.06 liters

This means a stirplate starter has 180 million/ml and the simple starter has 67 million/ml. That is a huge difference IMO.

If you go on to read about millions/ml, you will see that MB Raines has given a fairly big range to stirplated starters at 180-360 million/ml. So these numbers coincide with Jamil's.

I have found that I usually average 200-225 million/ml with a stirplate. I do a crude but effective test by measuring yeast slurry concentration per ml.

Thanks dfohio.

I think you are manipulating the calculator to do something that it isn't meant to do. I'm not sure what variable Jamil has in the calculator that changes the concentration/ml like that. Yeast concentration per ml is what you should be focusing on instead of changing the gravity to match starter size.

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But it should still get the same numbers or at least close shouldn't it? This really has nothing to do with the actual beer to be pitched into...just the starter (you knew that just restating it). It's telling me that 1 pack plus X liters of starter yields Y number of yeast cells (shouldn't matter how we manipulated the "# of Yeast cells needed in billions'). I wonder why it doesn't agree?

I have found that I usually average 200-225 million/ml with a stirplate. I do a crude but effective test by measuring yeast slurry concentration per ml.

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Thanks for these numbers. Good to know. I assume that is starting with a reasonably fresh Activator smack pack or WL vial?

EDIT: Nice 12-string. I want one of those new Taylor 8-string baritones sooooo bad.

tomwirsing said:

Split the difference. Buy a 1.5 liter jug of Carlo Rossi in the flavor of your choice. Consume. Clean. Make starter.

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hmmm anyone else try this? good choice for starter?

SpanishCastleAle said:

Thanks dfohio.


But it should still get the same numbers or at least close shouldn't it? This really has nothing to do with the actual beer to be pitched into...just the starter (you knew that just restating it). It's telling me that 1 pack plus X liters of starter yields Y number of yeast cells (shouldn't matter how we manipulated the "# of Yeast cells needed in billions'). I wonder why it doesn't agree?

Click to expand...

I am not sure why Jamil has concentration/ml dropping as the gravity of the intended beer increases. Probably the same reason why I don't know why he doesn't have smaller than 1 liter starter sizes. I'm guessing there is a reason for it.

SpanishCastleAle said:

Thanks for these numbers. Good to know. I assume that is starting with a reasonably fresh Activator smack pack or WL vial?

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Actually, it didn't matter. A smackpack or a stepped up 10 ml frozen vial yielded the same count on my stirplate. It has to do with the limited concentration of cells/ml.

SpanishCastleAle said:

EDIT: Nice 12-string. I want one of those new Taylor 8-string baritones sooooo bad.

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Thanks, too bad its a stock photo because I am a bad photographer. I actually own a Taylor 6-string grand auditorium with Indian Rosewood. Love it.

mixmasterob said:

hmmm anyone else try this? good choice for starter?

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I have used the gallon jugs on my stirplate. It can be tricky to position the bar due to the raised bottom, but it can be done.

Probably the same reason why I don't know why he doesn't have smaller than 1 liter starter sizes. I'm guessing there is a reason for it.

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I think that's because he recommends not making starters less than 1L when using Activator packs or WL vials. It allegedly is not ideal for yeast health and he stresses that yeast health is even more important than yeast count.

From the Fourteen Essential Questions...:

Q: I’ve heard that too small or too large a starter can be bad for the yeast. How is that possible?

Parker says putting a fresh vial of yeast into 500 ml of wort and letting such a small starter go to completion can actually leave the yeast less ready to ferment a batch of beer. The yeast do not rebuild their reserves and have very little increase in cell mass.

The minimum starter size for significant yeast growth from a vial or pack of yeast is 1 liter. One vial or pack into 1 liter results in approximately a 50% increase in cell mass.

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Results of my rinky-dink O2 diffusion experiment upcoming.

My rinky-dink experiment (inconclusive at best imo but w/e):

The O2 monitor does not have a 'probe' but is a small handheld unit with a built-in sensor so I couldn't use a flask, I had to use a 4L beaker in order to get the monitor inside the 'fermenter'. I put about 1" of water in the bottom with a stirbar and placed it on a stirplate. I did not have CO2 (or dry ice) so I ran some plastic tubing from an inert gas source to the bottom of the beaker. I hung the portable O2 monitor such that it's sensor was facing the water and was about 1.5" above it. Then I covered the beaker reasonably tightly with foil (we'll change this later). The gas tubing and the tie-wrap I attached to the O2 monitor prevent a good seal at those two points anyway (I ran the gas tubing out of the pour 'spout' of the beaker).

At first I used GN2 because it was most readily available. It might be interesting to note that when using GN2 I had to use an unreasonable amount of flow just to purge the O2 out of the beaker and when I reduced the flow the O2 level went right back up. So I checked the molecular weight of GN2 and found that it is almost exactly the same as air (and ever so slightly less): GN2=28.01 and Air=28.97. The molecular weight of CO2 is significantly higher at 44.01. One other inert gas I had available; Argon, has a much closer molecular weight to CO2: Ar=39.95. So I switched to Argon and it was WAAAAY easier to purge the beaker and keep it purged.

First I purged the beaker by flowing faster than any reasonable starter fermentation. That got it down to about 0.3% O2 fairly quickly/easily and I didn't try to go any lower. Then I dialed back the flow to what seemed like a reasonable 'high krausen' bubble rate. Then I waited to see if there was an equilibrium point it would reach with no stirring, just some bubbling (within a reasonably short time frame). After about 30 minutes it was at 0.6% O2.
Then I turned on the stirplate and got a nice vortex, considerably more than just a dimple on the surface. After about 30 more minutes the monitor read 0.9% O2. Then I loosened the foil (stirplate still going) and the monitor climbed all the way up to 3.0% O2 in just 15 minutes.

The beaker obviously has a much larger opening at the top (7“ diameter). I had way more headspace than what most of us would have in; say a 2L flask; and the liquid level was much farther away from the top than a typ 2L flask starter. What the combined effect of these are I don’t know. The larger opening should allow air in more easily and the larger headspace should make it much harder to purge out the air. Also, a fermentation has CO2 coming out of solution over the entire surface, creating a more even upward ‘push’. The gas tubing in my experiment was bubbling against one side of the beaker so I would think that created some small ‘currents’ in there. I pre-purged the beaker with Argon which doesn’t happen in a starter fermentation but we usually have WAY less headspace (i.e. less gas to purge).

So I'm not sure if this showed anything other than:
The fact that CO2 is much heavier than air makes a huge difference in how much air remains in and gets into a flask of fermenting beer.
Covering your starter loosely vs. tightly does seem to make a difference.

Obviously, there is some rate of fermentation that would drive off all the initial air and would prevent any air from getting in (eg - otherwise chemists couldn't work with hypergolic substances in plain ole lab exhaust hoods and have the toxic vapor detector never make a peep ) but I'm not sure if we reach that rate.

dofohio said:

I think you are manipulating the calculator to do something that it isn't meant to do. I'm not sure what variable Jamil has in the calculator that changes the concentration/ml like that. Yeast concentration per ml is what you should be focusing on instead of changing the gravity to match starter size.

Click to expand...

SpanishCastleAle said:

But it should still get the same numbers or at least close shouldn't it? This really has nothing to do with the actual beer to be pitched into...just the starter (you knew that just restating it). It's telling me that 1 pack plus X liters of starter yields Y number of yeast cells (shouldn't matter how we manipulated the "# of Yeast cells needed in billions'). I wonder why it doesn't agree?

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FWIW, I PM'd jamilz about this and he was kind enough to respond. Cliff notes are:

The numbers in the calculator are correct and have been independently verified. Always trust the calculator numbers.

The text in the 14 questions is a compromise between me and folks at white labs and wyeast. It is more general advice than hard and fast numbers.

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Thanks for pursuing that.

Like I said before, I have experienced 180 million/ml with my stirplate but that is crude.
I have not tested at every step up and I am not doing true cell count by dilutions and streaks. I just do the test every time to make sure there was adequate cell production.

Here is where I got the info for that general test

http://www.wyeastlab.com/com-yeast-harvest.cfm

I know that in one of the BN podcasts, JZ says that Chris White did independant tests and collaberated with him in creating the calculator. I see no reason not to trust either.