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

[mixmasterob]

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

hmmm anyone else try this? good choice for starter?

 

[dfohio]

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?

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.

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

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.

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

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.

 

[dfohio]

hmmm anyone else try this? good choice for starter?

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.

 

[SpanishCastleAle]

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.

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.

Results of my rinky-dink O2 diffusion experiment upcoming.

 

[SpanishCastleAle]

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.

 

[SpanishCastleAle]

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.

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?

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.

 

[dfohio]

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

 

[Pleepleus]

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.