How To Use A Stir Plate?

[Kimalinkas2]

Hi All.

When making a starter with a Stir plate - is there any special method or timeline that should be followed? Should you leave it turned on the whole time or for only the first 12 hours?

I have read and heard snippits that a stir plate should be used differently depending on what you are doing. By this I mean if you are culturing up from a coopers stubbie I have heard you are meant to stir the crap out of it for as long as possible but if you are using a wyeast starter pack perhaps only for 6 hours.

Any advanced stir plate users out there advice welcome!

Cheers.

 

[Wolfman]

Having built my getto stir plate I am also interested in some info on this.

 

[CosmicBertie]

The use of a stirplate, IMO, is to keep the yeast in suspension and to add air into the starter. For me, I have it running approx 24 hours a day, in which time it will probably have fully fermented out. I'm always surprised at how much yeast there is once its settled out.

 

[Jazzafish]

right or wrong, I let it run. I try to get it started 2-3 days in advance and then pitch the lot in an ale. Its usually at high krausen type of stage when I pitch. Lagers or light ales I crash chill after 4 -6 days and discard the liquid before pitching.

 

[seamad]

I run mine continually until done, CC for two days , pour off the bbeer, let it rise to pitching temp and pitch. Dont want oxidised beer mixed in with my brew, probably gives some off flavours.

 

[argon]

How you use the stirplate has more to do with how you intend to use the yeast in the wort.

As a rule of thumb, there are 2 options;
1. if you are going to pitch the entire volume of starter, limit the stirring to 24hrs or less or once high krausen appears. Continuing to stir beyond this point will introduce point will introduce further oxygen to the starter, potentially oxidising it and creating off flavours. So naturally you dont want to be adding this to your main wort.
2. If you are planning to decant the starter wort and pitch only the yeast, then you can leave it going the whole time prior to decanting. Typically i leave it about 24-36 hours. After that im not seeing a whole lot more yeast production. When decanting the oxidised wort in the starter is removed from the yeast and hence you wont be adding any associated off flavours to your main wort.

 

[mckenry]

Hi All.

When making a starter with a Stir plate - is there any special method or timeline that should be followed? Should you leave it turned on the whole time or for only the first 12 hours?

I have read and heard snippits that a stir plate should be used differently depending on what you are doing. By this I mean if you are culturing up from a coopers stubbie I have heard you are meant to stir the crap out of it for as long as possible but if you are using a wyeast starter pack perhaps only for 6 hours.

Any advanced stir plate users out there advice welcome!

Cheers.

I have been using a stir plate for about a year, and before that, just intermittent shaking.
Since this -> Yeast Calculator came along, my starters and therefore ferments have been fantastic. [Sample pool 4]
Its really good for working out optimum builds. My ferments have had massive pillows of krausen on them since using this calc.
The quick answer to your question is, I usually leave the stir plate going overnight, then step up the next day, or pitch if final count is reached.
So, overnight means anywhere between 8 and 15 hours. I have stepped up 1/3 of a wyeast into enough cells to pitch into 50L at 1.050 in a couple of days and the ferment was perfect. FG was spot on too.
In summary - get your cell count and growth rate right. The time doesnt really matter - its just oxygenating a starter. The starter tastes crap anyway. Just building cells. I assume you know the reat of the deal, re decanting the liquid after yeast has settled etc?
mckenry

 

[cdbrown]

How you use the stirplate has more to do with how you intend to use the yeast in the wort.

As a rule of thumb, there are 2 options;
1. if you are going to pitch the entire volume of starter, limit the stirring to 24hrs or less or once high krausen appears. Continuing to stir beyond this point will introduce point will introduce further oxygen to the starter, potentially oxidising it and creating off flavours. So naturally you dont want to be adding this to your main wort.
2. If you are planning to decant the starter wort and pitch only the yeast, then you can leave it going the whole time prior to decanting. Typically i leave it about 24-36 hours. After that im not seeing a whole lot more yeast production. When decanting the oxidised wort in the starter is removed from the yeast and hence you wont be adding any associated off flavours to your main wort.

Argon - do you chill it down after the 36hrs or just assuming that the yeast you want to use have already settled?

 

[argon]

Yep I chill it as part of my decanting process, typically 24 hours or so. There's heaps of yeast still in suspension and you can see the yeast slurry has significantly increased once chilled.

 

[iralosavic]

So if you're building up a lager population from a wyeast sample (ie 30ml), what would you do?

Put 30ml into 300ml wort, chill after 24 hours, decant in further 24 hours and repeat in 1L and 3L volumes of wort?

(I just threw in some random volumes, as I'm a noob to lager starters).

 

[argon]

I don't decant in between steps. Just chuck it all in with the next batch of starter wort.
Also I step up by 10 for ales = 100mL - 1L. And step up by 4 for lagers = 100mL - 400mL - 1600mL

 

[MaestroMatt]

How you use the stirplate has more to do with how you intend to use the yeast in the wort.

As a rule of thumb, there are 2 options;
1. if you are going to pitch the entire volume of starter, limit the stirring to 24hrs or less or once high krausen appears. Continuing to stir beyond this point will introduce point will introduce further oxygen to the starter, potentially oxidising it and creating off flavours. So naturally you dont want to be adding this to your main wort.
2. If you are planning to decant the starter wort and pitch only the yeast, then you can leave it going the whole time prior to decanting. Typically i leave it about 24-36 hours. After that im not seeing a whole lot more yeast production. When decanting the oxidised wort in the starter is removed from the yeast and hence you wont be adding any associated off flavours to your main wort.

+1

However, I find that if your stir-plate has the ability to alter the speed of the stir (i.e. you might have a pot in line with your system), I ensure the stir is vigorous for the first 24 hours - so as to introduce plenty of oxygen. After 24 hours, I will turn down the speed so that all the stir plate is doing is barely keeping the yeast in suspension. Usually I will leave it for another day before I pitch - so two days before brewing.

By doing this, I have absolutely no problems in throwing in the whole starter (usually about 1.2L) in. I give it a small taste test most times and no oxidization can be found.

 

[iralosavic]

So for a lager starting with 30ml yeast you would:
1. prepare a 100ml wort, cool to pitching temps, pitch 30mls of yeast, chuck on the stir-plate for 24 hours (or until high krausen)
2. prepare a 400ml wort, cool to pitching temps, pitch previous (~130ml) starter into it... Stirplate for 24 hours. (need 600ml min flask)
3. 1600ml wort, repeat. (need 2200L min flask) Is this enough yeast for a 20-25L ferment (assume standard yeast viability)?
4. Can't continue with 4x volume with this process, so if not enough yeast yet, chill and decant and add 5L wort?

Also how important is it to use a flask that matches the volume of wort? Ie would 100ml in a litre be too shallow to achieve a vortex? Is there a rule of thumb for this?

 

[argon]

That's pretty much how I do it... Except I prep all my starter wort at once (up to 2L) into individual sterile containers, like little no chills.

No need for the flask to be appropriately matched to the size of the starter. 100mL is fine in a larger flask.

I use 200mL glass juice bottles then into a 2L flask or glass bottle. If I need to go bigger I have a 10L plastic bucket that sits on my stir plate fine.

 

[iralosavic]

Apologies if this is taking the topic on a side-journey, but I thought the answers might be helpful to anyone who would have otherwise found this thread useful.

The calculators I usually use (for ales) assume 100% original smack pack contents are used. If I'm using a 30ml sample (let's assume viability is 50%), how do I estimate my yeast population after the first three steps (100ml, 400ml, 1600ml)
to determine if a fourth is necessary and if so, how much wort should be used to hit the target final cell count?

At a guess, I would say that these three steps would not be sufficient to pitch a typical lager strain into 20-25L, but without knowing the approx population, it would be easy to still underpitch or even overpitch, both of which I'd rather avoid.

 

[Wolfman]

Thanks for all the great info guys.

I think I have my all grain process under control. I have now started this venture into liquid yeast, starters and stir plates! So much to learn about this obsession!

What do you guys think about hooking the stir plate up to a timer? I had it on for an hour off for an hour? Was going great guns like this. Then I thought on for 15 off for 15 so the yeast stays in suspension?

Following on from Tonys article and instrucions about splitting wyeast packs I only made up a 2L wort to 1.038 and split the yeast into 3 vials and poured the rest into the flask of wort. I did spill some trying to pour into the vials, cut the pack the wrong way, so pitched another of the vials as after 24 hours nothing was going on. I am confident that this batch will be OK
Now having now found the Yeast Calc I am going to start to step up from now on.

Like I said SO MUCH TO LEARN!

 

[Camo1234]

I did spill some trying to pour into the vials, cut the pack the wrong way,

Get yourself a plastic syringe from the chemist and boil this at the same time as boiling the vials... then use that to get the yeast out of the smack pack and into the vial... Works a treat and no spillage :beer:

 

[Wolfman]

Get yourself a plastic syringe from the chemist and boil this at the same time as boiling the vials... then use that to get the yeast out of the smack pack and into the vial... Works a treat and no spillage :beer:

Consider that done.