Using A Magnetic Stirrer During Fermentation

[RobW]

Have any of you blokes with magnetic stirrers tried using them in a fermenting wort? I guess it would be more applicable to ales than bottom fermenters but it seems like it could be useful in maintaining consistent fermentation temperatures and stopping flocculant yeasts from dropping out too soon.

Judging by the way it kicks off starters it could reduce fermentation times too.

Alternatively, for those yeasts that need rousing, if you had a stir bar in the wort you could just switch on the mag stirrer at the appropriate time - easier than trying to swirl a full fermenter and less contamination & oxidation issues than opening the lid & using a paddle.

Interested in any feedback.

 

[Doc]

I've thought about it, and even consulted Dr Chris White (Whitelabs) on his last trip to Oz.
One thing first though; have you ever tasted the beer from a starter you've done on a stire plate. The resulting beer is very thin and watery.
When I posed this to Chris he mentioned this would happen also if done for fermentation. The yeast would not provide the flavours we want for finished beer.
Great for propogating, bad for fermentation.

Beers,
Doc

 

[Jye]

I was thinking of trying this with mead after reading they have a slow fermentation.

Airgead maybe you could comment on this :huh:

Have any of you blokes with magnetic stirrers tried using them in a fermenting wort? I guess it would be more applicable to ales than bottom fermenters but it seems like it could be useful in maintaining consistent fermentation temperatures and stopping flocculant yeasts from dropping out too soon.

Judging by the way it kicks off starters it could reduce fermentation times too.

Alternatively, for those yeasts that need rousing, if you had a stir bar in the wort you could just switch on the mag stirrer at the appropriate time - easier than trying to swirl a full fermenter and less contamination & oxidation issues than opening the lid & using a paddle.

Interested in any feedback.

Would it have any benefits only having it on until high krausen ?

 

[Stagger]

I am doing it right know, I have a lager stop at 1020 so placed the stirrer under and away I go. This is not the first time I have tried it, around 6 months ago I had a ale stop, gave it a stir and away it went. I have had no bad flavours or watery beer for the one time I tried it, however I do 50l so maybe have something to do with that.

Stagger

 

[RobW]

I've thought about it, and even consulted Dr Chris White (Whitelabs) on his last trip to Oz.
One thing first though; have you ever tasted the beer from a starter you've done on a stire plate. The resulting beer is very thin and watery.
When I posed this to Chris he mentioned this would happen also if done for fermentation. The yeast would not provide the flavours we want for finished beer.
Great for propogating, bad for fermentation.

Beers,
Doc

Was there any explanation why this happens Doc?

Sounds like from Chris White's comment & Stagger's experience it's OK for starters & rousing but that's all.

 

[poiter]

I have just begun to use a stirrer, not for stuck ferments, but for making starters and was wondering,
1. How long to keep the stirrer going?
2. Is it ok to add more cooled wort to the already stirred starter and stir again to step it up without risking oxidation?
If you're stirring the wort in your fermenter, you must have a pretty solid base for your stirrer.
Cheers, poiter.

 

[Trev]

I use a stir plate quite regularly but I've heard of many different methods of use.

For me, I use it to initially aerate the starter and then I turn it back on at random intervals (whenever I remember) so as to bring everything back into suspension.

Some others use it much more aggressively, keeping it running with maybe a 50% duty cycle.

If I was going to get very nerdy on it, I'd probably put a timer on it that had it on and off in 5 minute cycles

As for adding more wort, I'm thinking that as long as the yeast are in that stage where they multiply, then fine and dandy. They use up the O2 as part of their budding and multiplication. As long as there is a larger volume, and more nurtient, then I think its OK.

You want to simulate what happens when yeast stumbles across a nice healthy meal. Lots of O2, lots of sugars and alots of volume. This I believe is the basis for the 10:1 rule - as you step up a starter you multiply it by about 10 times.

Trev