[klickitat jim]

I might be overthinking this but isn't that a yeast selection issue?

[Whiskers]

It was my understanding that it also has to do with pitch rate.  If you only pitched one tenth of your james bond starter, and disregarding bacterial contamination, wouldn't the resulting beer be quite different? 

Even if you started with a typical English strain, wouldn't the beer be too 'clean' if your initial cell count was to high, say by pitching a double james bond into 3gal of 1.045 wort?   

[hopfenundmalz]

She scores the maximum of thirty as an introvert on Meyers -briggs and won't let anyone take her picture.

I scored pretty high on the introverted scale on the Meyers-Briggs Type Indicator.  I am an INTP.

So am I. As I get older, it is easier to put the introvert part on the back burner, and be a little more outgoing. There are times I like being quiet and contemplative, so year the NHC is draining.

We just got back from a road trip out west, and some of those lonely landscapes were outstanding for the soul.

[RPIScotty]

...how could one manipulate their starter protocol..

If I've been listening and absorbing anything Mark has been saying then you could reduce your starter volume, thereby reducing maximum cell density of the starter, thus pitching less yeast (i.e. reducing pitch rate).


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[klickitat jim]

Re Wiskers post 47

Thats what has been said, but clearly yeast strain choice is the primary way of controling flavor. Then comes temperature in my experience. Pitching rate, in my experience, has the least effect of the three. For example if you want X character from the fermentation then most of that control comes in yeast choice, followed by fermentation temperature,  and after all that maybe there is some fine tuning with pitch rate. I think this is even more true with pitching at high krausen. Pitching quiescent slurry may have slightly more control with pitching rate changes, though I never experienced it myself when pitching quiescent slurries.

[Whiskers]

I seem to recall Mark posting in one of these threads that he wanted an extra-ester English beer so he "underpitched" by some amount.  Can't recall the specifics of the strain choice.  I don't recall there was a manipulation of the temperature though.  Pretty sure pitch rate was the primary tool for the ester manipulation. 

[RPIScotty]

I seem to recall Mark posting in one of these threads that he wanted an extra-ester English beer so he "underpitched" by some amount.  Can't recall the specifics of the strain choice.  I don't recall there was a manipulation of the temperature though.  Pretty sure pitch rate was the primary tool for the ester manipulation.

Look at my response to you above. Reply #48

[Whiskers]

I saw it, thanks Derek. 

[klickitat jim]

I seem to recall Mark posting in one of these threads that he wanted an extra-ester English beer so he "underpitched" by some amount.  Can't recall the specifics of the strain choice.  I don't recall there was a manipulation of the temperature though.  Pretty sure pitch rate was the primary tool for the ester manipulation.

I vaguely recall that too. Maybe he will fill in the blanks for us. But what im saying is 1 yeast strain, 2 temp, 3 pitch rate maybe. So I'll bet he used an English strain (1), I'll bet he didnt ferment it at the cold end(2). At the risk of sounding ridiculous,  im sure he didnt use 05, fermented at 50, but underpitched to try to make it English. Point being that if there is flavor control from pitch rate, its minimal and way behind strain choice and fermentation temp. At least thats wha I ive experienced.

[S. cerevisiae]

Thanks for the write up.  The test is very clear.  I do have a couple of critiques - hope you don't mind.  Readability would be greatly improved if the equations were written with an equation editor rather than as text. 

I am working within the constraints of the blogging software.  I had to write raw HTML just to get superscripts.  I sure as heck do not want to have to resort to inserting graphics just to have pretty equations.   

The goal of the equations was to get across the impact of exponential growth without confusing people with too much mathematics.   I put in the asymptotic plug for the computer scientists in my readership.  That being said, I also recognize that many brewers struggle with basic algebraic equations.   

I'd like to understand, and perhaps others would as well, how pitching rates, cell/membrane health, and O2 (of the starter wort and eventual beer wort) affect ester/phenol/higher alcohol production in the final beer. 

It seems that within the advanced homebrewing community, most people are more concerned with developing a certain flavor balance rather than struggling with fermentation where the yeast have not owned the wort.  There's a lot of leeway in initial cell count with regards to time-before-wort-is-owned, but how do the replications affect the other critical aspects?  I understand all yeast behave differently in this regard, but what about general trends?  If cell count is low down the totem pole, how could one manipulate their starter protocol to make a very ester-filled mild vs. being very confident that their pils is nearly free of esters? 

I do understand that there is plenty of information out there about these questions, but perhaps the gospel is not what we thought it was, especially in regards to the over-reliance on cell numbers in the past.

First off, there is no such thing as an ester-free beer.  Even lagers contain esters and higher alcohols. If they did not, the finished beer would taste just like the wort, which we know is not true.  Secondly, I plan to cover many other areas in future blog entries.  It is just that many of those areas are not fully developed.  My focus in the near future is to distill information that I have posted here in various threads into coherent blog posts, so that I do not have to keep repeating the same information in different threads.  I also plan to blog about yeast related things that are of interest to me personally that may or may not have anything to do with the nuts and bolts of fermentation.   

One thing that people need to keep in mind is that most blogs are usually written for middling readers, and this blog will be no exception.  There is a fine line between being not technical enough and being too technical, especially when the subject involves mathematics and/or science.  Hopefully, no one had the idea that I planned to write a blog for elite brewers. 

[S. cerevisiae]

I vaguely recall that too. Maybe he will fill in the blanks for us. But what im saying is 1 yeast strain, 2 temp, 3 pitch rate maybe.

You are correct. Esters are a combination of all three aspects.  This information is currently spread across a bunch of threads.

[gdlbrewingco]

Thanks a lot for sharing this excellent article.


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[denny]

Re Wiskers post 47

Thats what has been said, but clearly yeast strain choice is the primary way of controling flavor. Then comes temperature in my experience. Pitching rate, in my experience, has the least effect of the three. For example if you want X character from the fermentation then most of that control comes in yeast choice, followed by fermentation temperature,  and after all that maybe there is some fine tuning with pitch rate. I think this is even more true with pitching at high krausen. Pitching quiescent slurry may have slightly more control with pitching rate changes, though I never experienced it myself when pitching quiescent slurries.

THIS^^^^^pitching rate is a very inexact way to try to control flavor.

[Whiskers]

OK - so if you were shooting for a very low ester pils or a high ester bitter, one would use the appropriate yeast and temp., but keep the 1L/5gal bond starter for all but high gravity worts?  Any reasonable exceptions? 

When journal articles specify that some experiment was done with such and such a cell count, is the assumption that this is a nominal cell count, and that the real/viable/healthy count is significantly lower due to the yeast being from a harvested slurry?  The reason I'm asking is because when texts mention pitch rate/cell count (not meaning homebrew conventional wisdom here), the ranges tend to be higher than what a 1L/5gal bond starter would deliver. 

[charles1968]

I'd like to understand, and perhaps others would as well, how pitching rates, cell/membrane health, and O2 (of the starter wort and eventual beer wort) affect ester/phenol/higher alcohol production in the final beer. 

^This. Not just how but why. There are so many bogus theories on the net about how yeast produce more esters when they're "stressed" by high temperatures (though temps higher than beer fermentation are optimal for yeastl) or stressed by low population (actually competition for resources is minimal when cell count is low) or going through a "growth phase" (yeast cells are continually growing and dividing throughout the whole fermentation cycle). It's perhaps the one topic that is most full of misunderstanding and pseudoscience on forums. A clear account of what really goes on would be invaluable.