Homebrewers Association | AHA Forum

General Category => Yeast and Fermentation => Topic started by: a10t2 on May 10, 2010, 04:52:28 AM

Title: Pitching rate effects (experimental results)
Post by: a10t2 on May 10, 2010, 04:52:28 AM
I (and some very generous volunteers from the NB forum) recently conducted an experiment to determine what, if any, impact under-pitching would have on a beer. The results more or less conform to the conventional wisdom - slower fermentation, increased off-flavors, etc. I know a lot of people, especially new brewers, question the need for starters, and I think the tasters' results make a pretty persuasive case for using them.

Yeast Pitching Rate Results (http://seanterrill.com/2010/05/09/yeast-pitching-rate-results/)
Title: Re: Pitching rate effects (experimental results)
Post by: tom on May 10, 2010, 04:16:24 PM
That is fantastic. Thanks for the indepth analysis.
Title: Re: Pitching rate effects (experimental results)
Post by: glitterbug on May 10, 2010, 04:28:13 PM
That is fantastic. Thanks for the indepth analysis.

+1000
Title: Re: Pitching rate effects (experimental results)
Post by: richardt on May 10, 2010, 04:43:21 PM
Thanks for the post.  It humbly reminds us that it is the yeast that make the beer.

I used to think doing a yeast starter was overkill (Erlenmeyer flasks, stir plates, test tubes, etc.) and an unnecessary expense.
I thought, "What's the difference if I pitch one cell or 100 Billion--it will eventually multiply and ferment the beer and finish the same?"

I was only half right--the FG finishes the same, but it doesn't taste the same. 
Use a starter to ensure you have enough healthy yeast to do the job right.

Now, I just need to get my fermentation fridge set up to ensure the yeast have optimal temperatures in which to do their work...
Title: Re: Pitching rate effects (experimental results)
Post by: bluesman on May 10, 2010, 04:43:28 PM
I experienced this first hand when I first started brewing many years ago. This is a testament to the fact.

Really nice work!
Title: Re: Pitching rate effects (experimental results)
Post by: majorvices on May 10, 2010, 04:52:51 PM
this will provide a valuable link for the nay sayers and/or beginners who question the need for a starter. Thanks!
Title: Re: Pitching rate effects (experimental results)
Post by: denny on May 10, 2010, 06:24:23 PM
I think I preferred the underpitched beer if I read the results correctly!   :-[
Title: Re: Pitching rate effects (experimental results)
Post by: dbeechum on May 10, 2010, 06:32:00 PM
Very nice.. I tossed a link to it up on the Falcons website.
Title: Re: Pitching rate effects (experimental results)
Post by: abraxas on May 10, 2010, 06:37:28 PM
9/30 testers could correctly identify the underpitched sample.

I wonder if this is related to about 25% of the population being "Supertasters"?
http://en.wikipedia.org/wiki/Supertaster (http://en.wikipedia.org/wiki/Supertaster)

It would be interesting to see if there was a correlation between their tasting/brewing experience level and correct identification.
Title: Re: Pitching rate effects (experimental results)
Post by: denny on May 10, 2010, 06:40:38 PM
It would be interesting to see if there was a correlation between there tasting/brewing experience level and correct identification.

Not in my case!   :(
Title: Re: Pitching rate effects (experimental results)
Post by: glitterbug on May 10, 2010, 06:43:11 PM
I think I preferred the underpitched beer if I read the results correctly!   :-[

From the article:
Based on the relative frequencies of some words, I think one can reasonably conclude that the under-pitched beer was perceived to be more bitter, more astringent, more solventy, less sweet, and – bizarrely – cleaner than the beer using the standard rate. Obviously, the increased perception of negative characteristics makes a persuasive case for the use of higher pitching rates.



Title: Re: Pitching rate effects (experimental results)
Post by: denny on May 10, 2010, 06:55:29 PM
I think I preferred the underpitched beer if I read the results correctly!   :-[

From the article:
Based on the relative frequencies of some words, I think one can reasonably conclude that the under-pitched beer was perceived to be more bitter, more astringent, more solventy, less sweet, and – bizarrely – cleaner than the beer using the standard rate. Obviously, the increased perception of negative characteristics makes a persuasive case for the use of higher pitching rates.

Cleaner and more bitter were the 2 attributes I detected that made me prefer the underpitched beer.  To me, the properly pitched one seemed "flabby".
Title: Re: Pitching rate effects (experimental results)
Post by: narvin on May 10, 2010, 07:12:54 PM
What was the OG of the Amber?  Also, what type of aeration was used?  There are definitely a lot of factors at play when it comes to ester production, so although it is always a good idea to pitch "enough" healthy yeast, it would be interesting to know what other parameters were used in this specific case when looking at the results.
Title: Re: Pitching rate effects (experimental results)
Post by: Kaiser on May 10, 2010, 07:28:57 PM
Nice experiment and, even better, a detailed write-up of how you arrived at your conclusions. The large number of tasters who were not able to tell a difference or preferred the underpitched beer reminded me of my Kraeusen skimming experiment. But for that I did not have as many tasters as you had.

One thing to note, which I also noticed in other pitching rate experiments, was that underpitched beers don’t necessarily end up being more estery and fruity than beers pitched with more yeast. There is a lot written in home brewing literature that suggests that underpitching leads to fruity beers.

Kai
Title: Re: Pitching rate effects (experimental results)
Post by: denny on May 10, 2010, 07:56:00 PM
One thing to note, which I also noticed in other pitching rate experiments, was that underpitched beers don’t necessarily end up being more estery and fruity than beers pitched with more yeast. There is a lot written in home brewing literature that suggests that underpitching leads to fruity beers.

Kai


I agree completely with this.  I often cite Dr. Clayton Cone of Lallemand who says that beers with lower pitching rates should be less estery.
Title: Re: Pitching rate effects (experimental results)
Post by: majorvices on May 10, 2010, 08:32:16 PM
I think sometimes people get confused between "estery" and "solventy".
Title: Re: Pitching rate effects (experimental results)
Post by: tygo on May 10, 2010, 08:34:47 PM
Denny, did you see a difference in head retention between the two when you did your tasting?
Title: Re: Pitching rate effects (experimental results)
Post by: a10t2 on May 10, 2010, 08:47:22 PM
What was the OG of the Amber?  Also, what type of aeration was used?

The OG was 1.059, and they were aerated for 10 minutes using an aquarium pump and plastic air stone. The recipe and notes from the actual brew session are in the first post (http://seanterrill.com/2010/02/18/yeast-pitching-rate-experiment/).

Denny, did you see a difference in head retention between the two when you did your tasting?

He noted better retention in the control.

(Sorry to answer for you, Denny!)
Title: Re: Pitching rate effects (experimental results)
Post by: denny on May 10, 2010, 08:56:50 PM
He noted better retention in the control.

(Sorry to answer for you, Denny!)

I appreciate it, Sean.  That way I don't have to dig out my notes!
Title: Re: Pitching rate effects (experimental results)
Post by: glitterbug on May 10, 2010, 09:11:56 PM
Cleaner and more bitter were the 2 attributes I detected that made me prefer the underpitched beer.  To me, the properly pitched one seemed "flabby".

Based on this experiment, would you consider making future brews without a "proper" starter?
Title: Re: Pitching rate effects (experimental results)
Post by: mashweasel on May 10, 2010, 09:50:56 PM
I'm not sure about the reason for this experiment. This experiment, along with a massive number like it (high/low gravity, yeast viability, generation mutations, etc) have been done. Not just done but done in a properly controlled lab setting. Kai and I have chatted about things like this quite a bit. Its a big pet peeve of mine for people to blindly do experiments without doing any basic research to see if anything like this has been done. Kai does a good job of finding original sources and then replicating the experiment to the best of his abilities. I'm not crapping on the effort here boys, what Im still wondering is that how this data is supposed to hold water. The vast majority of studies is not based on subjective analysis rather objective. Samples pulled are tested for numerous things along with being put on an HPLC to determine exactly what the differences are. Meaning levels of ethanol, isoamly alcohol, ethyl hexanoate, etc etc. There are tables that indicate sensory anaylsis of the human palate and the correlation with the amount of some chemical. Meaning that they can correlate the amount of X in a beer to the average human perception of it. My case in point: http://www.mbaa.com/TechQuarterly/Abstracts/1996/tq96ab09.htm Patino does some very good work.

Recently Chris White did a good job of summarizing high gravity fermentations of which pitch rate was talked about a lot:
http://www.ahaconference.org/presentations/2008/ChrisWhite_HighGravityFermentation.pdf

To this specific experiment, in my professional opinion, here are the biggest problems I see. This is not meant to bring down the one doing the experiment but to help them, and everyone else, where small changes can make very large effects:

- vernacular - if one are going to do research use the terms that everyone uses in the industry. Pitching rate is always discussed at millions of cells/ ml not billions/ L.
- yeast age - 52 days is very very old for a slurry even under the best conditions. CO2 toxicity is a big deal.
- yeast count - Assuming number of cells in a 'starter' is an absolute no-no. If one doesn't count the yeast, the experiment can't be done.
- yeast starters - the starters need to be done exactly the same way, same speed stiring, etc etc. Regardless of anything else, they should have at least been done together and then split at the very end.
- Yeast viability -  Irregardless of your actual number you are pitching you have no idea of how viable they are (eg. methylene blue stain). Are you sending in old grannies or soldiers? Very important. Additionally, decanting starters is very hairy in that how much is too much to decant, how much did you lose etc etc.
- Experimental controls - Three beers are needed. An underpitch, an over pitch and a 'correct' pitch. Two beers doesn't give enough variables.
- OG - Its just too high. What would be a yeast pitch rate experiment to one has change, instantly, to a yeast pitch rate of high gravity beers...unless you wanted to do a high gravity experiment but I didn't read that.
- Open fermentation and headspace - It wasn't clear to me if this experiment was done fermenting 'open' in buckets or in buckets with a lid. If they were closed the head space was absolutely massive which could skew the experiment. Books have been written on 'fermenter-head space' specifics.
- Yeast choice - The yeast type makes a massive difference in the outcome of the experiment.
- Sensory evaluation - should have been done using a double blind test and not a triangle test. The double blind takes all of the bias out.
- Format of sensory form - Its much easier to get good data but using a polar type plot for assessing peoples subjective perceptions. Also called a 'spider plot'. http://www.appellationbeer.com/images/20091217-spider.jpg
- Data presentation - the data should be presented in a histogram format with the average indicated. This way one can acutal see where each individual lands. A simple sd and T-test would be very easy to do if you did the spider plot.
- Summary of the summary - Using a starter makes better beer. This had absolutely nothing to do with the actual experiment.

Yes this list is extensive but all the points I've listed are not exhaustive. They all need to be addressed for all experiments and not just this one. That's why data is always peer reviewed. Point short, there is nothing I can ascertain from the data presented. There are too many holes for even the smallest assumption to be made.

This is the world I work in. When data is presented its up to the researcher to be able to support it. If someone doesn't show people whats expected for make an actual assumption they we are all living 'blind' and will allow falsehoods to continue and hearsay to continue.

Cheers

Kristen
Title: Re: Pitching rate effects (experimental results)
Post by: Kaiser on May 10, 2010, 11:06:21 PM
While I agree with Kristen on the importance of peer review we have to acknowledge that most of us don't have access to most of the good papers. Though our experiments do oftentimes lack the control and precision of professional reseach I support and encurage them. Maybe at some point one of us runs into something "odd" that warrants better experients and reseach.

Kristen came up with quite a list of concerns. Many if which I totally missed. Though it may reduce the validity of the conclusion it's good that you data was detailed enough to allow for this critique.

Cheers,
Kai
Title: Re: Pitching rate effects (experimental results)
Post by: narvin on May 11, 2010, 12:54:36 AM
Well, it's a big pet peeve of mine when people say "irregardless".

That aside, I think this experiment was supposed to contribute some practical information about making a starter versus using average age yeast from an LHBS directly.  And while this is far too complex of a topic for generalizations without knowing OG, amount of aeration, and a number of other variables, I think it actually reflects homebrewing conditions better than most laboratory experiments. 

So, it may not be that useful to the brewing chemists at Coors. Likewise, most of what they do is not useful to me.
Title: Re: Pitching rate effects (experimental results)
Post by: glitterbug on May 11, 2010, 12:57:32 AM
Well, it's a big pet peeve of mine when people say "irregardless".

That aside, I think this experiment was supposed to contribute some practical information about making a starter versus using average age yeast from an LHBS directly.  And while this is far too complex of a topic for generalizations without knowing OG, amount of aeration, and a number of other variables, I think it actually reflects homebrewing conditions better than most laboratory experiments. 

So, it may not be that useful to the brewing chemists at Coors. Likewise, most of what they do is not useful to me.

+1


Title: Re: Pitching rate effects (experimental results)
Post by: richardt on May 11, 2010, 01:12:09 AM
Drink something yellow and let's be mellow, guys.  It's just ideas we're discussing. 

Dr England's comments regarding the poor scientific methodology employed with most zymurgological "studies" are accurate.
While detractors may argue that forums (fora, for you Latin purists) like this one and unscientific magazines like Zymurgy that primarily target the general public are not to be held to the same standards as professional, peer-reviewed articles and journals, both Kristin and Kai make good points about applying more rigorous scientific standards to any "studies" that do get published.

I applaud those who find the homebrewing hobby (or "obsession") so fascinating that their childlike curiosity compels them to conduct an experiment.  But, most of these studies are quite poorly designed with regards to their hypothesis, materials and methods employed, the use of objective and standardized metrics, and arriving at unsupported and biased claims and conclusions.

As a homebrewer, I'd actualy respect your opinion more if you just wore flip flops and a loud tropical shirt and said, "Well... in my experience, underpitching yeast blah blah blah (insert your opinion here)."  Otherwise, it's just dogma hiding behind the scrim of science.

"The greater the ignorance the greater the dogmatism."

-Sir William Osler
Title: Re: Pitching rate effects (experimental results)
Post by: narvin on May 11, 2010, 01:40:22 AM

I applaud those who find the homebrewing hobby (or "obsession") so fascinating that their childlike curiosity compels them to conduct an experiment.  But, most of these studies are quite poorly designed with regards to their hypothesis, materials and methods employed, the use of objective and standardized metrics, and arriving at unsupported and biased claims and conclusions.

As a homebrewer, I'd actualy respect your opinion more if you just wore flip flops and a loud tropical shirt and said, "Well... in my experience, underpitching yeast blah blah blah (insert your opinion here)."  Otherwise, it's just dogma hiding behind the scrim of science.

"The greater the ignorance the greater the dogmatism."

-Sir William Osler


Well, that's slightly patronizing.  I agree with "Dr. England's" last sentiment (and I'm not questioning his credentials, but the only professor I ever had who actually told us to call him "Dr." was completely clueless) -- that allowing word of mouth myths to perpetuate only harms the hobby.  But most of his objections are basically excuses to dismiss without even commenting. Not sure about the reason for this experiment?  Don't be obtuse.  It you think that testing different procedure or ingredients in a homebrew setting with only "subjective" sensory analysis is a waste of time, just come out and say it.  But a useful contribution to making great beer is not necessarily the same as one that help us understand the metabolic pathways of yeast in a laboratory.

Your quote about dogmatic belief can apply to scientists as well.  I'm sure mathematicians smirk when they see biologists who are absolutely convinced they know what's going on with life ;)
Title: Re: Pitching rate effects (experimental results)
Post by: majorvices on May 11, 2010, 01:58:15 AM
Well said, in both posts Narvin. I'm not a ph.D or a Doctor and thank GOD I don;t wear flip flops or a loud tropical shirt but I thought the experiment was much  more approachable to the average homebrewer than some of the others I have seen, and was fairly well thought out as well.
Title: Re: Pitching rate effects (experimental results)
Post by: tygo on May 11, 2010, 02:16:58 AM
Well said, in both posts Narvin. I'm not a ph.D or a Doctor and thank GOD I don;t wear flip flops or a loud tropical shirt but I thought the experiment was much  more approachable to the average homebrewer than some of the others I have seen, and was fairly well thought out as well.

+10

Most homebrewing experiments that people conduct are similar to this.  Brew up a batch, split it up and vary a single variable.  Try as hard as possible to keep everything else the same and see what happens.  After that it’s based on our perceptions to evaluate the results.  As mashweasel points out there are plenty of factors which can skew these kinds of results.

Sean went out of his way to keep the variables as stable as he could and then conducted a much larger tasting than most would.  And now he’s presenting his data to us. 

Am I going to take the results as absolute gospel and go forth with no questions?  No, of course not.  But this was a very interesting and informative experiment and gave me several things to think about.  I think this was a great homebrewing experiment and I’m grateful for the information.
Title: Re: Pitching rate effects (experimental results)
Post by: mashweasel on May 11, 2010, 02:35:15 AM
Guys,

The points I list are not meant to be comprehensive in the fact that they prove/disprove any data. They are thought points.

Narvin, you have a very good point. I don't give indepth reasons for my points. I will absolutely go over point by point. That is a very good question. Just let me know what you think are the points I should cover and will. NP.

Every single publication offers free abstract's. The links I give show this. Most other publications can be found freely. If not, then a simple email to the person doing the study is all thats needed for more information. Nearly every person I know would email back freely with additional input that can't be read with plain 'text'.

As for the 'doctor' business, I am also one that is much laid back and has, nor will, be called doctor. My title is well earned as is why I use it. Nothing more.

As for the 'good enough' theory of home brewing 'experimentation' that really needs to stop. Nearly all of the points I list are very simple things to cover. Nothing that requires a ton of ability or research. Additionally, I haven't met a single home brewer that compares their wares to commercial products. We can't have it both ways. We can't say that our beers are better than the commercial thing but in the same breath say that we aren't held to any standard of experimentation.

Guys, again, the entire purpose of this post was not to show what I can see that you can't but to offer talking points in hopes that all the home scientists would see these things in future studies that they carry out. Its definitely not attacking the people carrying these out. I applaud these people.

Please continue the conversation and enough with the + (plus) agreements. State your questions. Thats how we all get better. My point rarely comes across the first time through of which I apologize. Kai and I have have had numerous conversations which entail this very thing. When one experiments in a vacuum one learns nothing.
Title: Re: Pitching rate effects (experimental results)
Post by: a10t2 on May 11, 2010, 02:44:09 AM
Its a big pet peeve of mine for people to blindly do experiments without doing any basic research to see if anything like this has been done.

Thanks for taking the time to respond in so much depth, Kristen. I did search for previous research in this area (I have access to a couple of the academic databases) and found some good papers, but they all dealt specifically with lagers, and none of them involved a large blind tasting. I'm sure those papers exist too and I simply don't have access to them, but I think it's important to keep in mind that most home brewers don't have access to any of the literature at all.

I'd like to respond to a few specific points. For the rest I'll defer to your superior knowledge and experience, and simply plead that I was working within the limitations of some very basic equipment.

- Experimental controls - Three beers are needed. An underpitch, an over pitch and a 'correct' pitch. Two beers doesn't give enough variables.

I'm not sure why that would be the case. Is an experiment that has one control and one experimental group inherently invalid? I do have *some* training in conducting a controlled experiment and I've never come across a statement like that.

- OG - Its just too high. What would be a yeast pitch rate experiment to one has change, instantly, to a yeast pitch rate of high gravity beers...unless you wanted to do a high gravity experiment but I didn't read that.

The OG was targeted to be at the high end of what White Labs and Wyeast say is "pitchable" for their standard (home brewer) products. Both manufacturers say a starter is only needed for OGs above 1.060.

- Open fermentation and headspace - It wasn't clear to me if this experiment was done fermenting 'open' in buckets or in buckets with a lid. If they were closed the head space was absolutely massive which could skew the experiment. Books have been written on 'fermenter-head space' specifics.

The fermenters were sealed and you're right, the head space is massive. Perhaps not ideal, but at least consistent between the two fermentations.

- Summary of the summary - Using a starter makes better beer. This had absolutely nothing to do with the actual experiment.

That's snarky and unscientific and maybe even inappropriate, but it actually does speak directly to what the experiment is designed to assess - do home brewers prefer beers pitched at a standard rate, or at the pitching rate associated with using a smack pack directly?

Point short, there is nothing I can ascertain from the data presented. There are too many holes for even the smallest assumption to be made.

I am disappointed to hear that you think that, since I respect and value your opinion. I guess all I can say is that I feel I learned some things as a result, and that those with a higher standard for proof will have to conduct their own experiments, or rely on the peer-reviewed literature.
Title: Re: Pitching rate effects (experimental results)
Post by: narvin on May 11, 2010, 02:58:15 AM
Well said, in both posts Narvin. I'm not a ph.D or a Doctor and thank GOD I don;t wear flip flops or a loud tropical shirt but I thought the experiment was much  more approachable to the average homebrewer than some of the others I have seen, and was fairly well thought out as well.

"Only two types of guys wear Hawaiian shirts ... and Bart doesn't look like a big fat party animal to me!"
Title: Re: Pitching rate effects (experimental results)
Post by: Kaiser on May 11, 2010, 02:59:43 AM
I too agree that the experiment itself is not invalid even though some of the parameters did not exactly match an actual 5 gal batch fermentation. The yeast amount could have been assed by its volume or the sediment weight.

I generally do side-by-sides where the beers are brewed 1 to 2 weeks apart. Though I'm aware that this is a problem I see these experiments as opportunities to find parameters that may be worth additional investigation or worth trying by other home brewers.

In the end it's all about the coclusions that are drawn and how much is put into the results and how strongly the conclusion is worded.

BTW, if you look at the Chris White's presentation you'll notice that in his experiments some of the flavor active components actuallty increased with pitching rate.

Kai
Title: Re: Pitching rate effects (experimental results)
Post by: a10t2 on May 11, 2010, 03:05:23 AM
The yeast amount could have been assed by its volume or the sediment weight.

In hindsight, that is something I wish I'd done, but my previous slurry volumes have matched up so well with the MrMalty predictions that I simply didn't feel the need. Shortsighted, I know...
Title: Re: Pitching rate effects (experimental results)
Post by: akr71 on May 11, 2010, 12:55:49 PM
Thanks Sean, I thought it was a great article!

Folks, lets keep in mind that we are talking about beer.  While we all love it, the only thing that is truly important is taste, which is purely and wholly subjective (IMHO).
Title: Re: Pitching rate effects (experimental results)
Post by: bluesman on May 11, 2010, 02:57:12 PM
Great discussion and debate. Great points made by Kristen. Definitely more things to consider upon further trials.
There are so many variables to consider when conducting an experiment of this nature. I am thankful to all the folks who have participated and especially Sean for conducting this experiment however flawed it may or may not be. But even more important than that it's what we have learned from this and how we will move forward as a community that counts. Keep up the great work!
Title: Re: Pitching rate effects (experimental results)
Post by: mashweasel on May 11, 2010, 07:53:37 PM
Ill just address the points as we go by briefly summarizing.

Re data access – the ability to access high end journals can get very expensive. What is not expensive, but free is the access to the abstract to any article pretty much ever written. Abstracts definitely don’t tell the entire story but will give one a very good idea of what is in the paper. Its basically a short summary of what was done and the results. Google Scholar is a good tool for the beginner.

Re controls – At the very end of the experiment you make the claim about a starter is better (we’ll get to that later). However, to have an experiment that holds water one always needs an unmanipulated control. If you wanted to test the validity of making a starter then you would need a non-starter control.

Re OG – Both do claim that you can pitch either product into <1.060 wort. However you are doing an experiment for the number of yeast to be pitched and the effects therein. In order to do this one first needs to understand that high gravity brewing is a beast of its own. This was not your experiment which needs to be addressed. Don’t get me wrong, this in and of itself is very much an experiment but not what you

Re fermenters – you are correct. Both fermenters were the same which does take out the effects that the individual fermenter geometry would play. It doesn’t, however, take into account the fermentation kinetics of that much head space and how the fermentations react/behave as such. This is something that is very easy to fix but at the same time this would not in and of itself ruin the experiment.

Re the summary – I’m not being snarky but I understand what you mean so let me explain further. You may have known what you were trying to do but in your summary and presentation it focuses on the difference between pitch rate and nothing to do with using a starter. Moreover, the starter creation is flawed as I have said before. Add to this there was no non-starter control making there no way that one can draw any solid conclusions. Let me put it a different way. What if I was trying to see if it was faster to ‘go by foot’, to ride a bike or drive a car through London in the same manner this experiment is done? I would have the car and the bike only competing. The car finishing the fastest followed by the bike shows absolutely nothing to do with how long it takes to ‘go by foot’. Does that make more sense?

Re ascertaining new knowledge from this experiment – you make a statement I hear a lot, ‘…I learned some things as a result.’ You may very well have learned things as a result but what are those things? One never really every ‘proves’ anything when doing experiments only basically disproves things. Read back through your notes, see what you can find. Go back over my points and see what you can improve. One of the most important things that I haven’t touched on are the number of repeats you did with this experiments. Meaning how many of each did you do in duplicate, triplicate, etc. The reason we do this is b/c single experiments are inherently flawed. Even if you kept everything the same it would have been better to do 2 sets of 3 one gallon fermenters.

Re the ‘its only beer’ theory – If people put the time and energy into doing an experiment, they, just like me, don’t want to be wasting their time. On top of that people brewing beer don’t want to be wasting their time. I very much understand that a lot of this technical knowledge hasn’t been seen by the average home brewer. Any sort of experiment people love. However one needs to take everything with a grain of salt. Does it make sense? Was it carried out well? Etc etc. This may be only beer but don’t tell me that if some dude did an experiment saying that olive oil should be put into a beer and then there is really no need for oxygen that if the beer then went south and wasn’t shelf stable people wouldn’t be pissed! BTW – this last one happened. Research New Belgium olive oil. A dude wrote his Masters on it if I’m not mistaken.

Please keep up this conversation as it helps everyone out.
Title: Re: Pitching rate effects (experimental results)
Post by: bluesman on May 11, 2010, 08:33:21 PM
Kristen,

You are a man that speaks with profound confidence on this subject. You get my vote to set up the next experiment on Pitching rate effects. I still have to give Sean credit for his work. Whether he proved or disproved the theory, he did a great job.

I see you may be in the running for this years Ninkasi. Good Luck with that!
Title: Re: Pitching rate effects (experimental results)
Post by: majorvices on May 11, 2010, 08:47:44 PM
Ill just address the points as we go by briefly summarizing.

Re data access – the ability to access high end journals can get very expensive. .... people wouldn’t be pissed! BTW – this last one happened. Research New Belgium olive oil. A dude wrote his Masters on it if I’m not mistaken.

Please keep up this conversation as it helps everyone out.


Kinda disappointed you didn't address the flip flop, Hawaiian shirt conundrum....
Title: Re: Pitching rate effects (experimental results)
Post by: narvin on May 11, 2010, 09:00:07 PM
I agree that if you're doing an experiment, you should do it properly, or it's not worth doing.  But I don't think everything has to be in commercial / academic terms -- no one here is trying to write a paper published in a journal.  What's the point of talking about cell count if most homebrewers don't have a hemacytometer?  Home-friendly units like starter size (as long as you can replicate the conditions -- stir plate, 1.040 OG, pitched one tube of White Labs, etc) are "good enough" in the sense that the pitching rate will be within a range that provides similar fermentations to other homebrewers.  Of course you can't pitch some old slurry from the back of your fridge and expect the same results, but there's enough info on making starters that homebrewers should know this.

Is brewing a science?  Is it engineering?  Is it art?  It's a little of everything, but in the end, what matters is that the beer tastes good, not that it has sound theoretical underpinnings.  A beer isn't going to become invalid like a public key encryption algorithm if the prior research turns out to be wrong.  I don't see any reason why science is a necessity to make a good beer that you can brag about and compare to the best commercial beers.  What about the cheese maker who knows nothing of the enzymes and molds that make the cheese, but knows exactly what to do and when to do it based on generations of trial and error?  Science can tell us why things are happening and help us to improve faster, and help to create consistency in large industrial settings, but it's not the end all for making great beer.
Title: Re: Pitching rate effects (experimental results)
Post by: a10t2 on May 11, 2010, 09:26:27 PM
Re the summary – I’m not being snarky but I understand what you mean so let me explain further. You may have known what you were trying to do but in your summary and presentation it focuses on the difference between pitch rate and nothing to do with using a starter.

I see, your concern is that I'm making a statement about starters when what was actually tested was the pitching rate associated with using a starter or not. You're absolutely right about that, and it's something I actually addressed briefly on the episode of Basic Brewing that will air tomorrow.

And by the way, I meant that I was being snarky (when I wrote that), not you.

One never really every ‘proves’ anything when doing experiments only basically disproves things.

I certainly wouldn't claim that this experiment proves or disproves anything - the data can only support or fail to support a hypothesis. There's no such thing as absolute proof. That fundamental fact doesn't validate or invalidate the data though.

One of the most important things that I haven’t touched on are the number of repeats you did with this experiments. Meaning how many of each did you do in duplicate, triplicate, etc. The reason we do this is b/c single experiments are inherently flawed. Even if you kept everything the same it would have been better to do 2 sets of 3 one gallon fermenters.

I do understand the importance of repeatability, but the one gallon fermenter idea seems a little impractical. If different tasters received beers from different fermenters, it would add an uncontrolled variable. And if each taster received beers from all three fermenters, it would demonstrate repeatability, but cut the sample size by a third.
Title: Re: Pitching rate effects (experimental results)
Post by: akr71 on May 11, 2010, 09:41:35 PM
... Please keep up this conversation as it helps everyone out.
Don't get me wrong, mashweasel, I thoroughly enjoyed reading your critique of Sean's experiment.  I'm no scientist, but the idea of a repeatable procedure & peer review is not new to me, so your insight was quite enlightening.  I also really enjoyed reading Sean's article.

Now, the 'only beer' thing I said...
Folks, lets keep in mind that we are talking about beer.  While we all love it, the only thing that is truly important is taste, which is purely and wholly subjective (IMHO).
All I was really trying to say was that we are all passionate about beer (or else we wouldn't engage in this hobby).  If Sean took the time to round up some tasters, gather their subjective opinions and write it up for us to enjoy, lets take it at face value - they are subjective opinions about beer.  Reading peer reviewed articles is great, but nothing beats the empirical evidence gathered by your own senses from a couple of frosty pints!
Title: Re: Pitching rate effects (experimental results)
Post by: dean on May 12, 2010, 03:58:47 PM
Kristen,

You are a man that speaks with profound confidence on this subject. You get my vote to set up the next experiment on Pitching rate effects. I still have to give Sean credit for his work. Whether he proved or disproved the theory, he did a great job.



Gotta give credit where credit is due, most homebrewers rely on other homebrewers for many experiments and very few of us are able to maintain a lab quality, controlled experiment.  I'm into it for the beer, yeh some are better than others but if I can brew a decent beer that other people like... why tell them I might have sneezed over the brew kettle?   :D  ;) 

I like being able to read a report without having to take a class to understand what a cyclotron or some other gadget is, don't get me wrong I do appreciate those experiments... I just wish those experimenters (scientists) wrote their report like they were addressing ME rather than a group of professional scientists in such a manner that it seems they are seeking a nobel prize etc.  We're "home"- brewers that like to dabble just enough to hopefully make decent beer on a regular basis for the most-part.   :D

Kris, yeh, I like reading your posts on what you've found or done too... but you're a bit wordy sometimes and I start drifting... not your fault but mine, I'm getting old and like to cut to the chase more now.

Sean... great job imo.   8)



Title: Re: Pitching rate effects (experimental results)
Post by: glitterbug on May 12, 2010, 05:35:05 PM
I like being able to read a report without having to take a class to understand what a cyclotron or some other gadget is, don't get me wrong I do appreciate those experiments... I just wish those experimenters (scientists) wrote their report like they were addressing ME rather than a group of professional scientists in such a manner that it seems they are seeking a nobel prize etc. 

You are not the intended audience for those types of experiments and reports and asking scientists to cater to your intellectual capacity is a little silly  :)
Title: Re: Pitching rate effects (experimental results)
Post by: Kaiser on May 12, 2010, 06:05:25 PM
I just wish those experimenters (scientists) wrote their report like they were addressing ME rather than a group of professional scientists in such a manner that it seems they are seeking a nobel prize etc.

I don't think that the write-up of the experiments should be simplified as much as possible in order to make them more understandable. Most of these write-ups are simply for the sake of documenting what was done which allows peer-review. This way the experimenter down't have to worry about the audicence.

However, I do agree that it is helpful to present conclusions drawn from the experiment in simple terms since this is what most other brewers are looking for.

Kai
Title: Re: Pitching rate effects (experimental results)
Post by: dean on May 12, 2010, 08:41:19 PM
Wow, I thought the major breweries had their own scientists and reports.  I guess I just thought discussing pitching rates for 5 or 10 gallon batches in an in-home setting was more of a home brewers issue.

Glitterbug, you're full of yourself aren't ya.  I believe you will teach one day.   ;)
Title: Re: Pitching rate effects (experimental results)
Post by: majorvices on May 12, 2010, 09:05:03 PM
My MO is just to read the first paragraph and the last paragraph. If there's more to it then that I give up. Hey, I did manage to read all of the Dune series and I understood at least 45 percent of it.
Title: Re: Pitching rate effects (experimental results)
Post by: narcout on May 12, 2010, 09:10:45 PM
http://www.mbaa.com/TechQuarterly/Abstracts/1996/tq96ab09.htm

"It was also found that higher pitching rates led to lower bitterness unit levels in the resulting beers (possibly due to the uptake of bitter substances by yeast cell walls and/or to increased foaming during fermentation) . . ."

I think it's cool that the tasters in Sean's experiment perceived the beer with the higher pitching rate to be less bitter.

It would be really awesome if someone who had access to and has read these scientific studies would put together a short summary of the results most relevant to homebrewers. Then we could all share in the knowledge. If the summary was citated, then people who were interested in more detailed results would have a guide as to which articles they might want to purchase in full.
Title: Re: Pitching rate effects (experimental results)
Post by: dean on May 13, 2010, 12:53:07 PM
I thought that was interesting too.  More than a few times I've questioned why some of my brews seemed more bitter than expected with astringency issues from time to time.  I use mostly dry yeast and usually teeter on the edge of underpitching anyway and then consider the date code on some packets.  I'm glad Sean did this home style experiment and shared it with us, I've learned something from it.   :)  8)
Title: Re: Pitching rate effects (experimental results)
Post by: weithman5 on May 13, 2010, 09:36:38 PM
not that this matters much but

i was a nuclear engineer and am now a doctor (why i am now broke)
i lived in hawaii but struggled with flip flops.

i don't have to know what wavelength of light is coming off my truck to know i love the old gray mare

i know that if i prime my lawnmower 3 times it will start if i prime it twice most times it won't (and i am a poor beer judge but i still enjoy a cold bud after mowing the lawn)

some people have good results with fly sparging, some with batch


as presented the information is helpful so that most of us can experiment and find out what works on  our own brew