Putting fermenter on a stir plate?

[MackerelQ]

I’ve done a fair amount of looking around for anyone who has posted on this topic and either I am the only one asking or I am not searching for the right thing or the answer is so intrinsically obvious that I am the only one missing the boat here. In any case, here’s my idea/question.

What would be the negative or positive effects of placing my fermenter on a stir plate during the first few days of primary fermentation?

I’ve seen time and time again people recommending stirring or agitating to wake up lazy yeast during slow or stuck fermentation. Why not put a stir bar in the fermenter and keep them swirling during the first few days? Any downsides?

 

[Nagorg]

I dont think thats really required to be honest. What would you be trying to achieve by doing this? The only thing I can think of would be for O2 but you'd be better off with an O2 tank from HD and a aeration stone...

 

[MackerelQ]

Nagorg, I agree- definitely not required. I see it like this: it’s great for yeast starters, why don’t we do it for fermenting our final product?

 

[radwizard]

The starter is solely to grow the yeasts population. You are adding the O2 constantly in a starter specifically to grow yeast, not create flavors. I usually don't even pitch that starter wort into the beer.

You only want to give the yeasts o2 when they are growing. Easy to do in 60 seconds with a cheap o2 set-up.

During your planning you should know how much yeast you want to pitch to get a desired profile, so what would be the point in making a giant stir plate?

 

[MackerelQ]

Radwizard, unless one is doing open fermentation the amount of oxygen the yeast is exposed to is the same if it’s being stirred or not (because it’s a closed system). I believe there are more benefits to the stirring than just oxygen absorption like keeping the yeast active. I don’t think you could actually get a full vortex from a 5+ gallon batch using a normal stir plate.

I do appreciate people’s input and advice, but I notice posters tend to not address the original question and provide argumentative statements instead. So, if anyone actually knows if there are any benefits (negative or positive) to using a stir plate on their fermenting wort, I would love to hear from you.

 

[Pkrd]

if anyone actually knows if there are any benefits (negative or positive) to using a stir plate on their fermenting wort, I would love to hear from you.

One benefit is to make you feel better about accidentally pitching your stir bar, yet again.

 

[radwizard]

I'm not trying to be "argumentative" at all. I'm just saying yeast need the O2 of constant agitation during the growth phase, and do not once the population is built and begin the fermentation stage.

If you are pitching enough yeast in the right conditions you should not need anymore agitation, the yeast themselves will do that.

So to address the question better... I see the positive benefits as being none. I can not think of one reason to agitate after fermentation has began.

 

[Imperator85]

Practically speaking, the type of stir plate most people use for stirring a yeast starter would not be capable of stirring a 5 gallon batch. It might also not be able to handle the weight or be properly balanced. A larger stir plate with an equally larger magnetic stir bar would be needed. In the lab, stir plates tend to get replaced by mechanical stirrers once your flask or reaction vessel gets to a certain size (and these rarely actually sit on the stir plate anyway).

Active fermentations are pretty convective, so moving things around is not really an issue until things have slowed down considerably.

 

[vtipsy]

Agitation with a stir plate can speed up the dry hopping process apparently:

http://brulosophy.com/2017/05/15/dr...on-vs-4-days-undisturbed-exbeeriment-results/

 

[SanPancho]

There are very large commercial systems that utilize recirc/agitation in fermenters. Decreases ferment time, fewer byproducts, etc.

Everything above is just random opinions. I’ll believe the europeos running the multimillion dollar plant on whether it has an effect or not. They aren’t exactly known for being wasteful or silly when it comes to this sort of thing.

 

[MackerelQ]

Thanks, SanPancho. That’s actually interesting and useful information.

 

[aamcle]

Somebody has to so here goes with the obvious answer.

Try it and let us know

For all we actually know it might make a huge difference.

It's something I've thought about my self but I'm not curious enough to motivate me to do the testing.


ATB. aamcle

 

[Northern_Brewer]

During your planning you should know how much yeast you want to pitch to get a desired profile, so what would be the point in making a giant stir plate?

There's two reasons which have nothing to do with oxygen levels per se. As has been mentioned above, it can help hop utilisation from your early dry hops. But also your carefullly-calculated pitching numbers will not be correct if you have a hard-floccing yeast that sinks to the bottom and is unable to access the wort. Think of it as a homebrew version of what happens in Yorkshire squares, some British yeast need regular rousing in order to perform as expected. You don't need a massive vortex, just enough to keep the yeast in suspension.

 

[schematix]

Most of the good points regarding oxidation and necessity have already been made.

I think the bigger issue you’ll encounter is finding a flat bottomed fermenter for the stir bar to be happy and stable on.

 

[SanPancho]

I thought of this myslef. Not using stir bar. Sit carboy on a lazy susan contraption from Home Depot. And use a slow turntable setting with a belt around the carboy.

Never followed through on the plan though.

 

[radwizard]

@Northern_Brewer

Cool. What type of stir plate are you using on your fermenter?
I understand the concept about dry hopping and agitation. I guess I assumed the yeasts themselves were doing enough agitation, or I could adjust that by adding a tad bit more hops.

From what I understand, agitation in the earlier stages of fermentation would speed up the growth phase. I'd guess that is primarily the interest larger scale breweries would have in recirculating, quicker turnaround times on product and fermenters.

It's all interesting stuff, though. It would be great to hear more about your system for constant fermenter agitation.

 

[Northern_Brewer]

Personally, my yeast-rousing system is nothing more complicated than a spoon - to be honest I've not had any need to go beyond that, my beers are generally not that "challenging" to yeast (<1050 OG, nothing too weird in the grist) so I don't need to show them too much love beyond the basics. But there's been lots of discussion in other threads on how to replicate things like Yorkshire squares at homebrew level, if you do a search.

 

[triethylborane]

Everything above is just random opinions.

Discrediting the "above" as random opinions without addressing them is not a valid approach. So the information regarding yeast starters is random and therefore to be ignored? This information applied to the OP's question should be dismissed because you say so? Incredible.

I’ll believe the europeos running the multimillion dollar plant on whether it has an effect or not. They aren’t exactly known for being wasteful or silly when it comes to this sort of thing.

An appeal to authority.

There are very large commercial systems that utilize recirc/agitation in fermenters. Decreases ferment time, fewer byproducts, etc.

Good info. Can/how this be applied to the homebrew scale?

I do appreciate people’s input and advice, but I notice posters tend to not address the original question and provide argumentative statements instead. So, if anyone actually knows if there are any benefits (negative or positive) to using a stir plate on their fermenting wort, I would love to hear from you.

Do you want genuine input or do you want responses that cater to your aims? Why can you not do your own analysis on this issue and provide the pros/cons so we can discuss them . . . instead of people taking your premise and providing their feedback as they see it? If you did your own analysis then we wouldnt have to be concerned about being argumentative with you.

 

[MackerelQ]

@triethylborane,

Wow, okay. Didn’t realize we were already in the “pissy flame war” portion of our program.

My question was simple. Does anyone know if there’s a positive or negative effect to constantly stirring the fermenting wort?

I didn’t feel that questioning my motives or getting into an esoteric discussion on pitch rates or the difference between yeast starter and beer wort or the difficulties of the practical application of this were in any way actually providing an answer or relevant information to the question.

As I said, I do value people’s input, but so many people like to respond when they don’t actually have any relevant knowledge on the subject. I think that’s what @SanPancho may have been voicing.

As to my lack of own analysis on this subject, I thought this forum was designed to be a platform for seeking and sharing knowledge.

I have yet to try this in my own practice and my research was searching this forum for anyone else who had potentially done the same thing. You seem to be implying I can only present fully fledged solutions and not ask a question for which I do not already have the answer.

Just like some of the prior posts, your response does nothing to address or actually answer the question. If you feel you need to parent the rest of us and let us know how much of a disappointment we are to the whole HBT community, could you kindly do it on a different thread. I’m actually trying to get some real information here and comments like these only serve to muddy the waters and are not germane to the subject.

 

[mediant]

I've seen this idea tested at Brulosophy a year ago, check it out here - http://brulosophy.com/2016/10/17/th...tion-during-fermentation-exbeeriment-results/

 

[MackerelQ]

Thanks @mediant, great find.

 

[Azura]

Someone made a big stir plate for the bottom of their bucket several years ago. They were promptly ridiculed. Sadly, they never reported if it did anything positive.

 

[Northern_Brewer]

One of the guys over on the BrewUK forum has reported results with stirring his dry hops that have been successful enough for him to stick with it, can't remember the details of his system though. There's been some academic papers to support the idea as well.

 

[Azura]

It's not happening with a stir plate. The system for recirculating dry hops that has academic support is basically pumping dry hopped beer out and returning it to the fermenter without introducing significant O2. A homebrewer could do this, but it's easier just to use an extra ounce of dry hops and be more patient. The primary benefit of the recirculation system was speed and efficiency.

 

[bleme]

I think there is a reason that every commercial brewery recirculates by pumping from the bottom to the top. That also seems considerably cheaper and more available to a homebrewer than finding a fermentor that won't throw the bar.

 

[SanPancho]

Discrediting the "above" as random opinions without addressing them is not a valid approach.

there were no scientific journals, experimental results, or other evidence based references in any of the posts so what else are they if not opinions? do they stick to the OP's original question regarding recirc and primary fementation? or veer off into asides about starters and dry hopping? and unless somebody here is hiding a doctorate in biochem or ferm science i guess that means everyone is just a rando from the interwebs, no?

so yeah. RANDOM OPINIONS.

and putting faith in a bunch of euros who installed these systems is not in any way deferring to authority as they are not commonplace and therefore could not be considered to be the "authoratative" version of brewing. but given that these are huge multimillion dollar facilities i defer to these guys HAVING THE BALLS TO MAKE SUCH A CHANGE.

 

[SanPancho]

well, no. thats kind of a recipe for disaster. to rouse yeast most folks throw a couple quick blasts of 30-40-50psi co2 into the bottom outlet.

for dry hop recirc you come off the racking arm typically, then down into pump and into the bottom outlet. blows all the sunken hops material up and into suspension.

you would never put suction from the bottom outlet and then back to the top as it would be likely to either clog or punch through the hops/yeast cake and you end up leaving most of it where it is.

 

[Gadjobrinus]

Personally, my yeast-rousing system is nothing more complicated than a spoon - to be honest I've not had any need to go beyond that, my beers are generally not that "challenging" to yeast (<1050 OG, nothing too weird in the grist) so I don't need to show them too much love beyond the basics. But there's been lots of discussion in other threads on how to replicate things like Yorkshire squares at homebrew level, if you do a search.

Not ready yet as my brew frame is nearing completion, but I do have the thought to just use my MLT, which is an almost ideal 1:1 aspect ratio, and Chugger to at least start the process of emulating the Yorkshire process - rather vigorous recirc according to the known cycle to target gravity. I don't have a fishtail spreader, but even that, hope to get fabricated. Just reslanted my HH from Brewlab so we'll see how it all goes.

 

[Azura]

The hop recirculation apparatus with academic support that was mentioned earlier is this:

I'm not an engineer, but it appears there is no stir bar in this set up. This information was sourced from Peter Wolfe's dry hop thesis which is free to view on the internet. A lot of good modern dry hop info is there. The image and sensory table was cut and pasted with my homebrew comment.

Continuous stirring during fermentation has been studied by brewing scientists. However, it's not something that is widely used to make beer regardless of scale.

 

[SanPancho]

dont forget to reference the part about astrigency and polyphenol harshness. its a delicate dance. wouldnt want folks to start shakin the hell out of their fermenters without knowing possible side effects.

 

[Azura]

dont forget to reference the part about astrigency and polyphenol harshness. its a delicate dance. wouldnt want folks to start shakin the hell out of their fermenters without knowing possible side effects.

Astringency and polyphenol harshness are not terms extreme hop heads worry about. Smelling the beer from at least two feet away from the glass is more important.

For two years in a row, I was a keg dry hop inverter/shaker every day for 5 days while using bagged hops. They were the most aromatic beers I've made using 4oz of dry hops. No enthusiastic IPA drinker that tasted the beers said they were astringent or harsh.

Then I got too lazy to invert the damn keg once a day for 5 days and my IPAs became less impressive, but I didn't really care. The beer still tasted good and had good enough aroma to be enjoyable.

Then I compensated for my laziness by using more unshaken hops. The flavor and aroma kicked up a notch or two.

 

[ba-brewer]

Not sure how this fits in but I believe one of the function of a stir plate is to push CO2 out solution.

There are some people on the American homebrew Association forum that believe a stir plate is a bad thing for yeast and use a shaken not stir approach. Something about pressure or forces damaging the yeast some how.
​

 

[SanPancho]

yeah, its pretty insane what folks will do on homebrew level- things that just would never scale into commercial beer- unless it was like $10/pint or more. its crazy. but damnit its good.

but joking aside- shaking your keg has little to nothing to do with the kind of forces generated by the impeller of a 5hp pump. even slowing it down you can still get some bad reactions.

i cant remember as it has been so long since it read that paper but i think it had alot to do with the green material. so in theory, things like hop powder would be a perfect candidate for recirc- pure flavor, no green material, no harshness or polyphenols. i havent used it yet, but from what i hear about issues with it not dispersing well and clumping sometimes, maybe a good blast through a pump could be a good solution if done o2-free.

 

[Azura]

Not sure how this fits in but I believe one of the function of a stir plate is to push CO2 out solution.

There are some people on the American homebrew Association forum that believe a stir plate is a bad thing for yeast and use a shaken not stir approach. Something about pressure or forces damaging the yeast some how.
​

CO2 will remain in solution if the head space pressure is more than or equal to the pressure of the solution. Since no one ferments starters with a truly closed pressure system, CO2 will escape solution.

The concept of stir plate starters being bad for yeast is silly. If it was bad for yeast, then I guess I have been very lucky 100% of the time hundreds of times. I'd rather be lucky than talented!

 

[ba-brewer]

CO2 will remain in solution if the head space pressure is more than or equal to the pressure of the solution. Since no one ferments starters with a truly closed pressure system, CO2 will escape solution.

The concept of stir plate starters being bad for yeast is silly. If it was bad for yeast, then I guess I have been very lucky 100% of the time hundreds of times. I'd rather be lucky than talented!

The amount of CO2 generated by yeast is greater than what can passively escape that is why your fermentor continues to bubbles even after fermentation is complete. Also if you throw your stir bar and put it back into action the starter will foam up some times. The BOMM approach to mead can also demonstrate the principle if you don't read the full thread.

I mentioned the shaken not stir approach because there are some people that think a stir plate it is not a good thing. I am not one of them. I believe they have studies to support the claims.

 

[Azura]

yeah, its pretty insane what folks will do on homebrew level- things that just would never scale into commercial beer- unless it was like $10/pint or more. its crazy. but damnit its good.

but joking aside- shaking your keg has little to nothing to do with the kind of forces generated by the impeller of a 5hp pump. even slowing it down you can still get some bad reactions.

Well you were the one who was really worried about home brewers getting harsh hop results from shaking the keg. Instead of shaking, I prefer to gently invert them for 1-2 hours once a day to let things mix when I'm not feeling lazy. Shaking a keg is something a 500 pound gorilla would do for no apparent reason. I can assure you, I'm not a 500 pound gorilla.

Since there are probably still zero homebrewers that have tested the apparatus in the pic I posted above that was published 6 years ago, how can you be so sure about what you are saying here? Presumably, you have tested this dry hop pump apparatus in the home brew scale? If yes, where did you talk about it?

And which homebrew pumps are 5hp? That's a lot of horses for homebrew! The typical Chugger is 1/20 hp.

 

[Azura]

The amount of CO2 generated by yeast is greater than what can passively escape that is why your fermentor continues to bubbles even after fermentation is complete. Also if you throw your stir bar and put it back into action the starter will foam up some times. The BOMM approach to mead can also demonstrate the principle if you don't read the full thread.

I mentioned the shaken not stir approach because there are some people that think a stir plate it is not a good thing. I am not one of them. I believe they have studies to support the claims.

I'm not disagreeing with anything you have said here. However, whatever 'study' claims a stir plate starter isn't good for my beer is irrelevant to me. I've made plenty of beer with and without stir starters and determined stir starters are worth doing. However, they aren't necessary.

 

[radwizard]

The thing i am not getting here is what are you hoping to accomplish... I get the concept of dry hop utilization through agigating, and understand why a commercial brewery would want to to trim a few days off the growth stage of fermentation. On a homebrew level, i just honestly cant think of what could be gained.

Im really not trying to be rude at all and i apologize if i was. Part of the question was if it so great for the starter then why not for the fermentation... in my rando opinion it wouldnt be purposeful.

Id love to learn something new and may be missing something. So the question id ask is, what is your goals with the method?

Cheers!

 

[Azura]

I've seen this idea tested at Brulosophy a year ago, check it out here - http://brulosophy.com/2016/10/17/th...tion-during-fermentation-exbeeriment-results/

Knit picking Brulosopher xBmts is like shooting fish in a barrel. This particular xBmt is significantly more flawed than the rest. If anyone thinks this is a valid brewing experiment, please defend it.

They used a home made cigar box 1-5L? stir plate to spin 18L of beer in a tall 5 gallon keg. What could possibly go wrong there? Pretty sure the stir bar kicked while the Brulosopher was sleeping and dreaming about being relevant.

Not surprisingly, the beers finished at the same FG and tasted the same according to less than 20 people.

 

[Azura]

The thing i am not getting here is what are you hoping to accomplish...

Id love to learn something new and may be missing something. So the question id ask is, what are your goals with the method?

Fair questions that deserve a fair reply from the OP. It's probably not going to happen now. No one said something that validated the OP's concept. A lot of people politely refuted it.