Author Topic: Right RPM for stir plate?  (Read 16123 times)

Offline Wort-H.O.G.

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Re: Right RPM for stir plate?
« Reply #105 on: January 17, 2015, 02:20:47 PM »

Wow! What a great thread that is hidden under this crappy title.
Yeah, I started this thread just expecting a simple nuts-and-bolts answer.  Then boom...no KA-BOOM!
This Forum is amazing!  A whole bunch of thoughtful, literate, respectful, fun-loving, BEER-loving folks talking about how to brew beer.  What you folks have done here deserves a very long slow clap!

Yeah you should edit the title so others find it. Something like starter: stir plate or not.


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Offline mabrungard

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Re: Right RPM for stir plate?
« Reply #106 on: January 17, 2015, 03:37:25 PM »
"My problem with stir plates is that they, like yeast rinsing, have been sold to the home brewing community based on faulty information.  A stir plate is a poor investment when used with an Erlenmeyer flask and a stir bar.  This setup has been sold to home brewers as a self-aerating, "set it and forget it" way to propagate yeast.  The craziest thing is that brewers who arrived on the scene after the introduction of stir plates have been taught that starter media is always too foul to pitch.  Foul smelling media is a sign that the yeast cells in one's starter are stressed."

...


"My post was meant to bring attention to the fact that temperature-controlled fermentation chambers are one of the first things that are pushed onto new brewers when they inquire about process improvement, not that there is never a need for temperature control.  More often than not, quality control problems have little to do with whether or not not a brewer is using tight or stepped temperature regulation during fermentation, especially when using a yeast strain that is as forgiving as BRY 96, which is the most popular yeast strain in home and craft brewing by a sizable margin.  The number one thing that will hold brewers back from producing quality beer is less than optimal sanitation."


Mark, I see that we agree on the uselessness of trying to propagate a starter without adequate oxygen. Aerobic conditions are REQUIRED for the yeast to synthesize sterols and just putting yeast in a narrow-ended flask is not going to keep the starter aerobic. Nor is a shot of oxygen, once or occasionally. I found that since the need for oxygen in keeping starter wort aerobic is relatively low, the use of air is OK...as long as its filtered adequately to prevent contamination. I understand that filtering at the sub-micron level should be sufficient to remove air-borne contaminants. I also found out the hard way, that using an air-stone for starter aeration is NOT required. Just pumping filtered air into the headspace over the starter wort is adequate. That should keep that headspace at over 19% oxygen content and that should easily transfer to the wort. I have to admit that my apparatus may be better suited for that transfer since I create 1 to 2 liter starters in a 6 liter ehrlenmeyer flask. That leaves a large surface area between the headspace and wort.

Mark, I have to point out your experience with the importance of temperature-control is biased. A basement in a home located in the northern US is actually a nicely temperature-controlled environment that is truly an advantage compared to those that live in a hotter climate and don't have a cool basement. You forgot to take of your blinders on that issue. While I am in the same situation as you...with a nice cool basement...I remember my days in Tallahassee and the dire need for temperature control then. For most brewers, temperature control is a critical step in producing high-quality beer.
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Re: Right RPM for stir plate?
« Reply #107 on: January 17, 2015, 03:48:42 PM »
my stir plate has very low speed...doesn't even make  a dimple on low speed-just swirls the wort. thats how I run my starters. there's just a lot of studies out there that will contradict your premise that a stationary starter without any o2 infusion (what most homebrewers do) will  produce the same amount of viable cells as the same on a stir plate. not my studies, just saying.

I recently stumbled upon a post made by Steven Deeds that blew my mind.   In that post, he made claims that mirrored my findings with respect to stir plates  (I always seem to be the fish that is swimming upstream within the home brewing community when it comes to yeast management).  Steven and I apparently came to the same conclusion in isolation.   After digging deeper into Steven's research, I found that he too discovered the "shake until almost all foam" method that I have been using since 1993.  Most home brewers who make a starter without a stir plate miss this critical step.   Swirling the culture into the media or shaking until a small amount of foam forms will not produce the same results.  One has to seriously shake the culture to produce that much foam, which requires the use of a container with a screw on cap or a sanitized rubber stopper that is held in place with one hand during the shake.  The container should also be at least three times the volume of the starter for best results (preferably four or more times the volume).



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Re: Right RPM for stir plate?
« Reply #108 on: January 17, 2015, 04:40:15 PM »
Mark, I have to point out your experience with the importance of temperature-control is biased. A basement in a home located in the northern US is actually a nicely temperature-controlled environment that is truly an advantage compared to those that live in a hotter climate and don't have a cool basement. You forgot to take of your blinders on that issue. While I am in the same situation as you...with a nice cool basement...I remember my days in Tallahassee and the dire need for temperature control then. For most brewers, temperature control is a critical step in producing high-quality beer.

If read all of my posts around where I first surfaced the issue, you will see that I put a disclaimer in for people who live in warm states.

However, that's not how low temperature ale fermentation or temperature ramped fermentation is presented in this forum and others.  It's presented as a requirement for quality ale production.  A temperature-controlled fermentation chamber is one of the first things that I see promoted when a new brewer asks about gear and/or process improvement even though the brewer is fermenting ale.  No one even bothers to ask what the ambient temperature is in the brewer's fermentation room before offering the suggestion.  It's all about using refrigeration for a process that can be performed in the high sixties/low seventies range with excellent results, a temperature range that is easily met for most of the year in below grade basements in states that experience four seasons. The trick is picking the right yeast culture for the task at hand, not tricking the yeast culture into performing the task at hand.  Those who live in warm states have no choice, but to resort to forced attemperation.

The original post was made to highlight the fact that a temperature-controlled fermentation chamber should not be the universal answer to improving fermentation quality, especially when the person making the recommendation has not asked the inquirer if he/she has space in his/her home that remains under 70F.

Over the years,  I have found that most home brewers who have quality issues from a fermentation point of view do not know how to clean and/or sanitize properly.   They also do not recognize how critical it is to be super anal when handling a yeast culture.   It is amazing how much a couple of hours spent teaching a brewer how to clean and sanitize his equipment as well as how to propagate yeast in a way that minimizes the risk of wild microflora contamination can go towards improving batch-to-batch consistency and overall quality. 

Offline HoosierBrew

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Re: Right RPM for stir plate?
« Reply #109 on: January 18, 2015, 12:03:21 AM »

Over the years,  I have found that most home brewers who have quality issues from a fermentation point of view do not know how to clean and/or sanitize properly.   They also do not recognize how critical it is to be super anal when handling a yeast culture.   It is amazing how much a couple of hours spent teaching a brewer how to clean and sanitize his equipment as well as how to propagate yeast in a way that minimizes the risk of wild microflora contamination can go towards improving batch-to-batch consistency and overall quality. 

I can see your point to an extent about sanitation. But I don't know, Mark - I've always been pretty 'sanitation OCD' even back before my beers were consistently good. And I remember (pre-temp control) a lot of beers that were perfectly clean but overly estery and fuselly. IIRC these were beers where I pitched from 70-72F for the most part.
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Re: Right RPM for stir plate?
« Reply #110 on: January 18, 2015, 12:52:45 AM »
I can see your point to an extent about sanitation. But I don't know, Mark - I've always been pretty 'sanitation OCD' even back before my beers were consistently good. And I remember (pre-temp control) a lot of beers that were perfectly clean but overly estery and fuselly. IIRC these were beers where I pitched from 70-72F for the most part.

Yes, but if one is pitching at 72F and the ambient room temperature is 72+, one is looking at peak fermentation temperature that could possibly exceed 80F due to the exothermic nature of fermentation.  Additionally, the culture becomes more active as the temperature rises, resulting in even more heat being produced.

I used to pitch ales at 70 to 72F on a fairly regular basis at my previous residence, but my basement was 66F and the carboy sat on a concrete floor, which acted as a heat sink.  My wort temperature would drop to around 66F before fermentation kicked into high gear, and would rarely go above 70F due to the concrete floor sinking heat from the fermentation vessel. 

One of the reasons why I hate plastic buckets is that HDPE has the lowest thermal conductivity rating of the "big three" materials that are used in the construction of fermentation vessels.  Stainless has a terminal conductivity rating of 16 watts per meter kelvin (W/(m·K)). Glass has a thermal conductivity rating of 1.05 W/(m·K).  HDPE plastic has a thermal conductivity of 0.42 W/m-K.   In essence, HDPE traps heat better than any of the materials commonly used in constructing fermentation vessels. 

Offline HoosierBrew

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Re: Right RPM for stir plate?
« Reply #111 on: January 18, 2015, 01:35:14 AM »
I can see your point to an extent about sanitation. But I don't know, Mark - I've always been pretty 'sanitation OCD' even back before my beers were consistently good. And I remember (pre-temp control) a lot of beers that were perfectly clean but overly estery and fuselly. IIRC these were beers where I pitched from 70-72F for the most part.

Yes, but if one is pitching at 72F and the ambient room temperature is 72+, one is looking at peak fermentation temperature that could possibly exceed 80F due to the exothermic nature of fermentation.  Additionally, the culture becomes more active as the temperature rises, resulting in even more heat being produced.

I used to pitch ales at 70 to 72F on a fairly regular basis at my previous residence, but my basement was 66F and the carboy sat on a concrete floor, which acted as a heat sink.  My wort temperature would drop to around 66F before fermentation kicked into high gear, and would rarely go above 70F due to the concrete floor sinking heat from the fermentation vessel. 

One of the reasons why I hate plastic buckets is that HDPE has the lowest thermal conductivity rating of the "big three" materials that are used in the construction of fermentation vessels.  Stainless has a terminal conductivity rating of 16 watts per meter kelvin (W/(m·K)). Glass has a thermal conductivity rating of 1.05 W/(m·K).  HDPE plastic has a thermal conductivity of 0.42 W/m-K.   In essence, HDPE traps heat better than any of the materials commonly used in constructing fermentation vessels. 

I should've given more info - at the time I was using glass carboys (before breaking, getting stitches, and going plastic) sitting on a concrete basement floor, too. Even using plastic now, I just like the beers better where I've pitched at 62, fermented at 64F (most strains anyway). Personal preference - I will say that, except for Belgian strains, I do prefer a pretty clean yeast character.
Jon H.

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Re: Right RPM for stir plate?
« Reply #112 on: January 18, 2015, 06:50:33 AM »
I brew very few American-style ales.  I like ale to have nice ester profile.   Most of the ale strains that I use are not neutral at normal ale fermentation temperatures.   


Offline klickitat jim

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Re: Right RPM for stir plate?
« Reply #113 on: January 18, 2015, 12:51:40 PM »


More award winning beers have been made without the aid of a stir plate than with one.

I'm going to pick on you here. Do you have a reference for this? What is the total count of awards won, and the % of non-stir vs stir? I've not seen competitions require the brewers to list what method of yeast propagation they used, but im new. Did they used to collect that info? Do any of these include awards won prior to the invention of electricity? Because that kind of unfairly stacks the deck in favor of the stirplatephobic hyperbole.

Offline Wort-H.O.G.

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Right RPM for stir plate?
« Reply #114 on: January 18, 2015, 02:10:58 PM »
Just poll A few folks Jim- you'll get your answer.

Mark- The point was not to statistically quantify award winning beer. Instead, I'm just contending that it's by no mistake Brewers make beer using starters and stir plates that taste great, win awards, and otherwise meet a standard developed to evaluate quality,

For me , as I said, if it tastes and smells like a great beer ( and that's me comparing to beers I've really Enjoyed) then it is a great beer. I will leave the award judgments to the judges.
« Last Edit: January 18, 2015, 02:18:20 PM by wort-h.o.g. »
Ken- Chagrin Falls, OH
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Offline hopfenundmalz

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Re: Right RPM for stir plate?
« Reply #115 on: January 18, 2015, 03:09:46 PM »
I would like to add that cold crashing at the end of the exponential phase reduces starter lead time from a couple of days to less than 24 hours when pitching a relatively fresh White Labs vial. This reduction in lead time means that a starter can be pitched the evening before one intends to brew, popped into one's refrigerator late morning the following day in preparation for decanting, and pitched late afternoon the following day.

I am going to try this.
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Offline brewday

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Re: Right RPM for stir plate?
« Reply #116 on: January 18, 2015, 04:28:18 PM »
I would like to add that cold crashing at the end of the exponential phase reduces starter lead time from a couple of days to less than 24 hours when pitching a relatively fresh White Labs vial. This reduction in lead time means that a starter can be pitched the evening before one intends to brew, popped into one's refrigerator late morning the following day in preparation for decanting, and pitched late afternoon the following day.

I am going to try this.

I just gave this a shot - pitching soon....

15 seconds O2 from the stone/red can, stopper w/airlock, no stir plate, no shake, no agitate, 18 hours, cold crash, decant, pitch.

No weird smells or tastes from the starter wort.  I probably could've crashed closer to 12 hours (WY 1968) based on what I saw.  My sense is that I have plenty of healthy yeast to pitch.  I'm hopeful that this leads to me permanently ditching the stir plate.

Awesome thread, thanks for the info Mark!  :D

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Re: Right RPM for stir plate?
« Reply #117 on: January 18, 2015, 05:10:03 PM »
One of the reasons why I hate plastic buckets is that HDPE has the lowest thermal conductivity rating of the "big three" materials that are used in the construction of fermentation vessels.  Stainless has a terminal conductivity rating of 16 watts per meter kelvin (W/(m·K)). Glass has a thermal conductivity rating of 1.05 W/(m·K).  HDPE plastic has a thermal conductivity of 0.42 W/m-K.   In essence, HDPE traps heat better than any of the materials commonly used in constructing fermentation vessels.

Once again, though, your objection is more theoretical than actual, at least in my experience.  In practice, having used carboys, buckets, and cornies, the difference in thermal conductivity makes little to no difference in actual use.  Your experience may differ from that, but mine is that they work equally well in terms of thermal conductivity.
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Offline denny

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Re: Right RPM for stir plate?
« Reply #118 on: January 18, 2015, 05:13:12 PM »
I brew very few American-style ales.  I like ale to have nice ester profile.   Most of the ale strains that I use are not neutral at normal ale fermentation temperatures.

And maybe this is the source of the differences...I brew 80% American ales and want the ingredients other than yeast to come through.  But even the Belgian and German styles I brew as the other 20% have benefitted from cooler fermentations.
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Offline HoosierBrew

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Re: Right RPM for stir plate?
« Reply #119 on: January 18, 2015, 05:19:48 PM »
I brew very few American-style ales.  I like ale to have nice ester profile.   Most of the ale strains that I use are not neutral at normal ale fermentation temperatures.

And maybe this is the source of the differences...I brew 80% American ales and want the ingredients other than yeast to come through.  But even the Belgian and German styles I brew as the other 20% have benefitted from cooler fermentations.

Yeah, that's what I was getting at, too. It's why I like Chico and 1450 for American styles - I like the malt and hops to shine and the yeast to mostly stay out of the way. I don't make as many British styles nowadays for this reason. And like you say, even Belgian beers (to me) are better started cool - I've had banana/phenol bombs from starting Belgian strains too warm. Just personal preference.
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