Stir plates...?

[Newtons Shed]

Hi
I've done some reading on yeast and looked at how to build stir plates but I don't understand what they actually do? Am I right in thinking as the name suggest it keeps the liquid vortexing I guess this is because other wise the yeast would settle out at the botom? To step the yeast up do you really need a stir plate to cultervate yeast or is just a nice to have?

After rebuilding the brewery I next want to concentrate on fermention and want to move on from rehydrating dried yeast to liquid yeast or capturing from donor bottles and build a bank of yeast up as I hope to brew at least once a fortnight.
Never used liquid yeast before, as thought no point until I can control the fermentation tempreture better (just in process of building the FV chamber and scrap fridge as cooler) I want to ensure I have enoght yeast count for either 25l or 50l brew lenght

Thanks

 

[Dave1970]

It does keep the yeast in suspension. It also helps the yeast reproduce by encouraging gaseous exchange. The movement will encourage CO2 out of solution and O2 from the atmosphere into solution. Both will help the yeast to reproduce.
You can do without, I cultured some Fuller's yeast from bottles using a demijohn. Every time I walked past I gave it a swirl and it worked fine.

 

[wilsoa1111]

agreed not essential but is meant to increase the yeast yields significantly,

but on my scale its a bit pointless, just brew a bigger starter or start with more yeast when culturing

besides flasks and stirplates in my neighbor hood would probably get me raided lol

 

[dennisdk2000]

Embarrassingly, this points out the fact that I don't really need a stir-plate - I just really want one...
Keep telling myself that all my little additions, while not strictly necessary at the moment, will be completely justifiable once I move on the brewing on a bigger scale... :whistle:

Dennis

 

[Dave1970]

You can self build one VERY cheaply. I think mine was
£1 for a pound shop food container
£3.50 for 2 Hornby power supplies delivered from Ebay
£1.50 for a pretty glowing fan from Ebay
screws/washers etc...mostly had enough hanging around had to buy 1 pack of machine screws for £1.50 ish

Not sure of exact price but well under a tenner and it glows!

 

[jonnymorris]

You can self build one VERY cheaply...

Mine was similar though I saved on the Hornby power supplies by using an old mobile phone charger. I think the magnetic stir bar was £3 and the magnets £2.

Using a stir plate will double the yield due to the benefits described by Dave above so worth it besides just being something to make.

 

[CRoark]

I've also read that using a stir plate improves on the condition and thickness of the yeast cell walls making them more resistant to higher alcohols and other things they don't like. I built my stir plate using parts off of an old computer (cpu fan, old hard drive for the magnet) and a multi voltage ac adaptor so I can control the speed, and a cigar box I got for free from a local tobacconist.