| Author |
Message |
    
Scott Folsom (141.156.14.53)
| | Posted on Tuesday, April 27, 2004 - 02:49 am: | 
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How many of you use a magnetic stirrer on your starters? I have 3 erlenmeyer flasks, a 500ml, 1k ml, and a big ol' 3k ml one I got cheap on ebay. I used to start in the 500 ml and step up twice, now I just start in the 1k ml and step up to 2k of wort in the big boy. I kind of like the idea of the magnetic stirrer, but I'm not sure if it actually makes that much a difference. I know it's supposed to produce healthier cells, but will I see the benifit of it?
thx
~S~ |
Jeff Sherer (172.158.222.115)
| | Posted on Tuesday, April 27, 2004 - 03:30 am: |
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It's a lot more fun and adds a whole new demention of geekitude to the process. Does that count as a benefit? ;-) |
Bill Freeman/ER (66.25.112.80)
| | Posted on Tuesday, April 27, 2004 - 04:04 am: |
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I have an unheated mag stirrer. When setting up a starter - I begin with 500ml and go to 2 L - I start the stirrer when adding the Wyeast or White Labs yeast sample along with pure O2. What I get is a faster, more active starter. I think that the end resulting yeast count is probably pretty much the same only that it is arrived at much sooner.
Remember to remove the stir bar before adding the starter to the wort or you will end up pouring the stir bar into the fermenter. There is a long handled magnetic pick up for doing this. |
Richard Nye (216.75.223.70)
| | Posted on Tuesday, April 27, 2004 - 09:23 am: |
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I use a stirrer, and I think it eliminates the need to oxygenate the starter (why oxygenate if you're continuously adding air to the starter). I loosely cover my 4L flask with aluminum foil and let it churn. Only disadvantage is my wife complains about the noise.
I use a magnet on the OUTSIDE of the flask to keep the stir bar in the flask when I pitch my yeast. |
Craig Johnson (172.194.194.82)
| | Posted on Tuesday, April 27, 2004 - 11:17 am: |
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I am 100% in agreement with Richard, including the wife's complaints.
If you are going to get a used stirrer check out www.labx.com. they tend to be about half the price of ebay. |
Scott Folsom (151.200.112.141)
| | Posted on Tuesday, April 27, 2004 - 11:17 am: |
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Well, I have already decided to get one. I just wanted to see what you guys had to say. Trolling ebay as we speak.
And yes, high geekitude factor always gets bonus points! |
John McElver (144.29.1.16)
| | Posted on Tuesday, April 27, 2004 - 12:03 pm: |
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Put the stir bar into the flask and starter wort before you process (boil or pressure cook) it.
It's easier that way.
If you forget and dump the magnet into the fermenter, it'll be OK, unless you have a conical with a bottom drain. Just don't dump it into the sink drain at the end!
Even geekier would be an orbiting shaker. No stir bars to mess with. It's what I grow bacterial cultures with at work. Of course, they're more expensive, and I use a stir plate at home.
Richard & Craig,
you can move the thing around somewhat and it'll generally alleviate the noise. Ting-ting-ting...
Of course, you could also spring for a stir bar float (a little teflon do-hickey that holds the stir bar just off the bottom) for maximum geek-dom.
John |
Bill Pierce (24.141.129.137)
| | Posted on Tuesday, April 27, 2004 - 12:16 pm: |
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I use a stir plate for starters. It speeds up the process and seems to produce more yeast.
As for the claim that aeration of the starter eliminates the need for aerating the wort, I don't buy it unless the starter size is *huge*, on the order of 30 percent or more of the batch size. Otherwise there is still considerable yeast reproduction taking place and the requirement for lots of oxygen. |
Fredrik (213.114.44.249)
| | Posted on Tuesday, April 27, 2004 - 03:41 pm: |
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Richard, do you leave the flask alone for the entire time without pump? then I wonder how oxygen you will actually supply, depending on the headspace, especially since the CO2 is on it's way out, most probably forcing the O2 out too eventually. Stirring or shaking alone will speed reaching saturation equilibrium but you still need to supply the oxygen itself. The bigger headspace the better though. I don't have a stirrer yet but I would sure like one  I guess a good way would be to supply oxygen or air continously in the stirrer, if you can filter it. If that is not an option I would at least flush the CO2 in the headspace a few times to get new air in there. To just keep stirring if there is nothing but CO2 in there will not bring oxygen to the yeast. But some stirring is possibly still favourable for other reasons.
/Fredrik |
Bill Freeman/ER (66.25.112.80)
| | Posted on Tuesday, April 27, 2004 - 04:48 pm: |
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I once made an O2 injector for a flask by drilling a second hole in the ferm lock stopper and inserting a small stainless aerater stone attached to a short piece of 1/8th copper tubing. I connected a pure O2 source to the tubing and let a small trickle of O2 run into the stirring starter wort.
I let the O2 flow for about the first 15 minutes and again after a couple of hours wait.
It is true that after the first minute or so the O2 in the head space of a flask is used up and further oxygen input is rejected once the starter begins to ferment and create CO2. |
Richard Nye (24.34.142.13)
| | Posted on Tuesday, April 27, 2004 - 08:44 pm: |
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I just set up the stirrer and let it go. I used to put an inverted glass over the top of the flask (supported by 3 short, slit pieces of plastic tubing placed on the lip of the flask). Now I just put a loose piece of aluminum foil over the mouth of the flask. I can get some sterile cotton gauze at work and I'll try that next. I don't know how much air makes it into the wort, but there is a pretty good vortex that probably draws fresh air into the flask. CO2 and air are nearly the same density, and I don't think there is a blanket of CO2 over the starter. Anyway, I get 4 hour starts and good tasting beer. |
Brews and Views Archive 2004 
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