Stirred Fermentation

[Sulli]

Sulli, I suspect the increased temperature in the stirred variant is from friction, which in my way of brewing is not a worry since increased temperature can happen in a pressurized fermentation with no ill effects. I am pumped about your results so far. I honestly was only interested in stirring from a maturation/aging faster standpoint, so your data is good to know. I can also assume (there is that damned word again that gets me into trouble) that a lot of the flavor aspects are from more suspended yeast and from CO2 being less in solution from being beaten out... but again that is only a assumption. I can't wait till the final finished product tasting information from you on these batches.
Again, I am thinking this is due to people thinking about open air starter type stirred fermentations. This is a closed air, as in "NO O2 after oxygenation and pitching" type of fermentation, and IMHO all that is happening is yeast are allowed a greater chance to eat more and faster. Even though the un-stirred is a point less, I feel they will equal out in time due to the stirred version being "green" a shorter amount of time.

I cannot wait to try this with a pressurized fermentation to see just how much one could shave off the time of a beer. My beer is already fully carbonated after primary all on it's own. Imagine carbed, matured, and in my glass in just over two weeks, and I mean READY not just DRINKABLE!:rockin:

heh heh, I applaud your enthusiasm Sounds like you enjoy playing with your beer as much as I do. I've been reading up on your method of using pressurized sanke kegs, sounds very interesting. I've put my buddies 20 gal boil kettle on this stir plate, dropped a stir bar in, and had a vortex going through about 10 gallons of water.[In fact I'm considering using this method in combination with an immersion chiller to cool my next 10 gal batch of wort] So I'm sure you could make it work with a sanke keg. Your gonna need some strong-ass magnets though.

 

[Sulli]

If the beers reached different temperatures during the first 36 hours, they will likely taste different. Temperature variances as little as 2 degrees F can have a dramatic influence on the flavor of any beer, especially ales fermenting above 60. Precisely controlled fermentation temperature is one of the most crucial elements in brewing. If your beers taste different, I believe this will come mainly from the different temperatures at which they spent their first 36 hours and have less to do with CO2 and/or yeast in suspension. I am interested to know how the final flavors of all three examples compare.

The stirred carboy kept about the same temp as the conical. I've got my Ranco set at 68/1/66/1 and it does a pretty good job holding 'em steady, I only have one temperature probe though, so I tape it the outside of the conical, since I figure it's going to be generating the most heat. This makes is hard to get the carboys much higher than about 65 degrees because the A/C is trying to keep the temps down on the conical. Maybe this is going to skew the results on the side by side between the carboys since the two non-stirred carboys fermented about 4 degrees lower than the stirred carboy; now that both the conical and the stirred carboy have slowed up, the temps have equalized across all the fermentation vessels and the non-stirred carboys have gained a few degrees. Could all equal out in the end. What are your thoughts?

 

[WortMonger]

heh heh, I applaud your enthusiasm Sounds like you enjoy playing with your beer as much as I do. I've been reading up on your method of using pressurized sanke kegs, sounds very interesting. I've put my buddies 20 gal boil kettle on this stir plate, dropped a stir bar in, and had a vortex going through about 10 gallons of water.[In fact I'm considering using this method in combination with an immersion chiller to cool my next 10 gal batch of wort] So I'm sure you could make it work with a sanke keg. Your gonna need some strong-ass magnets though.

You Sir are a bastard, for making me have to check this thread every time I walk into the room, lol. Enthusiastic is an understatement! Great work Sulli. So, these magnets you speak of, lol, strong due to the yeast or strong due to the amount of liquid. I am wondering about the tiny stir bar cutting through all the yeast you are seeing in your stirred carboy being the problem you are alluding to, but I am unclear. A little clarity on this matter will surely keep me up thinking even more tonight, lol.

 

[mightynintendo]

You Sir are a bastard, for making me have to check this thread every time I walk into the room, lol. Enthusiastic is an understatement! Great work Sulli. So, these magnets you speak of, lol, strong due to the yeast or strong due to the amount of liquid. I am wondering about the tiny stir bar cutting through all the yeast you are seeing in your stirred carboy being the problem you are alluding to, but I am unclear. A little clarity on this matter will surely keep me up thinking even more tonight, lol.

lol much?

 

[WortMonger]

How else does one show he is laughing at what he said so another doesn't get the wrong impression when I call him a bastard for completely blowing my mind by doing an experiment I wish I could do right this second? I wouldn't want him to take me serious on saying something I meant in jest.

 

[mightynintendo]

i'm just teasing you because you lol'd three times in one post like a grandmother on facebook.

 

[WortMonger]

You're a grandmother on facebook... what is a facebook?

 

[WortMonger]

^ humor

 

[WortMonger]

< Idiot

 

[mightynintendo]

< drunk

 

[mightynintendo]

our posts are so getting deleted... we are WAY off topic

oh right...

 

[WortMonger]

lol, BASTARD! I'm working on it. This WV game is a shut out, so I have been taking it easy.

 

[WortMonger]

Hey, no fair. I want a sign. Then again, I could be replaced with a bucket of sand with a sign in it that says, "Slow."

 

[Sulli]

^LOL'ed

 

[Sulli]

You Sir are a bastard, for making me have to check this thread every time I walk into the room, lol. Enthusiastic is an understatement! Great work Sulli. So, these magnets you speak of, lol, strong due to the yeast or strong due to the amount of liquid. I am wondering about the tiny stir bar cutting through all the yeast you are seeing in your stirred carboy being the problem you are alluding to, but I am unclear. A little clarity on this matter will surely keep me up thinking even more tonight, lol.

These are the magnets I have mounted on my stir plate, next time I build one of these I'll probably go to the next size up. The reason they need to be strong is that there is a lot of resistance from the volume of liquid you are trying to spin, so it tends to decouple the stir bar from the magnets at high speeds, not that you need high speeds to keep the yeast in suspension, it's just cool to be able to pull a vortex through 6 gallons of liquid. I'm using a 1.5" standard stir bar, but I have some dumbell shaped stir bars on the way, I think they will work better with the uneven convex surface of a carboy.

 

[WortMonger]

Damn those are strong magnets. I just use the ones I rip out of hard drives. They are very strong and flat.

 

[Sulli]

I had a couple of brewing comrades over last night, and we did some sampling on these beers, and several varieties of micro brews [I have the hangover to prove it. oy.]
The stirred carboy is now at 1.014; non-stirred 1.016; conical 1.012. I have to say, tasting these beers at varying specific gravities, has been very educational, especially for my palate. I'm really amazed at how much of a difference just a couple of points in gravity can make to the finish of a beer.

As far as flavor goes, all of the samples are very similar.
The sample from the conical has the best finish so far, I think this is mainly due to it being a slightly drier beer, like I said, I was surprised that I could detect a difference with only 2 points of gravity, but it was definitely there.
The stirred beer tastes great, If it drops those last 2 points of gravity, it will be an exceptional beer. I can't get Stone beers in Salt Lake City, I'm going to have to make a trip to Evanston so I can do a side by side.
Gonna leave em at temp for another week, then dry hop for one more.

 

[helibrewer]

I rouse daily all the way through conditioning then drop the temp for aging and leave it alone. It has worked very well.

 

[WortMonger]

So Sulli, explain real quick the stirring regiment (like when you started and when you ended the stir/etc). Is it still being stirred to help with maturation, or is it stopped to speed up settling? I am just curious. Oh, and the two points difference could be due to a difference in pitching rate or the shape of the vessel. I know you said you got the right amount for each, but unless all three batches were inoculated and then split, I think you would be off a little. I am so pumped there were no ill effects.

 

[Hermit]

When I thought about doing this I thought about treating it like a starter for at least the first 24 hours and put foil over the carboy instead of an air lock. I now have an oxygen setup though so extra oxygen would be trapped in by the airlock until it got used up or diluted and pushed out with the CO2. I could see this as a replacement for the O2 though. I got a free, full medical tank plus won a gift certificate that got me an .5 micron stone so I'm set for a while in that regard. Still, I think looking at turning this into an oxygenation technique for the first 24/36 hours might be worth looking into.

 

[Sulli]

So Sulli, explain real quick the stirring regiment (like when you started and when you ended the stir/etc). Is it still being stirred to help with maturation, or is it stopped to speed up settling? I am just curious. Oh, and the two points difference could be due to a difference in pitching rate or the shape of the vessel. I know you said you got the right amount for each, but unless all three batches were inoculated and then split, I think you would be off a little. I am so pumped there were no ill effects.

Let's see...I started the stir plate right when I pitched my yeast, and it ran for about 4 days, I'm using WLP007 so as soon as it flocculated, I could see it cruising around in big globs inside the carboy. That's when I turned the stir plate off, mainly, like you said, to let things settle out. In retrospect I'm thinking maybe I should have just let it run for a full two weeks. I dunno, experimentation is always full of 'should have's' and 'what-if's', next time I'll do it a little different. Probably run the stir plate for a full 2 weeks. So far, though, I'm pleased with the results. Thanks for askin'

 

[Sulli]

When I thought about doing this I thought about treating it like a starter for at least the first 24 hours and put foil over the carboy instead of an air lock. I now have an oxygen setup though so extra oxygen would be trapped in by the airlock until it got used up or diluted and pushed out with the CO2. I could see this as a replacement for the O2 though. I got a free, full medical tank plus won a gift certificate that got me an .5 micron stone so I'm set for a while in that regard. Still, I think looking at turning this into an oxygenation technique for the first 24/36 hours might be worth looking into.

^Worth thinking about.

 

[GNBrews]

[...]could have been the C02 that is still in solution, but it didn't seem nearly as smooth..

Is it possible that the dissolved CO2 is skewing your gravity readings, or are you degassing your samples? The conical would have the most dissolved CO2, which might explain the lower gravity reading. I have no idea how you're measuring gravity, but just an idea if it's not something you've thought about.

Cheers!

 

[bwomp313]

very cool experiment. definitely interested in your results and if you do more of these

 

[Sulli]

Is it possible that the dissolved CO2 is skewing your gravity readings, or are you degassing your samples? The conical would have the most dissolved CO2, which might explain the lower gravity reading. I have no idea how you're measuring gravity, but just an idea if it's not something you've thought about.

Cheers!

I do gravity readings with a refractometer, so this shouldn't be an issue.

 

[Sulli]

very cool experiment. definitely interested in your results and if you do more of these

cool, I will definitely be doing more, thanks.

 

[GNBrews]

I do gravity readings with a refractometer, so this shouldn't be an issue.

Surprisingly, it is. I also use a refractometer, and have found that the corrected gravity readings are as much as 5 points off unless I degass the sample.

 

[Sulli]

Surprisingly, it is. I also use a refractometer, and have found that the corrected gravity readings are as much as 5 points off unless I degass the sample.

Really? I had no idea...so, how would you degass a drop of liquid?

 

[GNBrews]

Really? I had no idea...so, how would you degass a drop of liquid?

Yeah, I was surprised as well. Though it makes sense if you think about it, since the gas is actually dissolved in the liquid.

I take about half an ounce sample, put it into an old White Labs yeast vial, and shake the hell out of it for a few seconds. Then, I take a drop or two from that.

 

[Sulli]

I just did a pretty thorough search of the web, and I can't find any information on the effects of c02 on the refractive index. I did find this website. Which says A refractometer with ATC (Auto Thermal Compensation) is unaffected by temperature or fermentation gases. Where did you get your information? Can you site some sources?