English yeasts and the miracle ester sweet spot of generation nr X

[beervoid]

Coming back to yeast pitching rates of CW if that is 240millon cells per ml
I calculated it back to 456 billion cells per 5 gallons that seems like a huge over-pitch.
I'm sure I'm doing something wrong.
If I use a yeast calculator the nr goes up tp 800+ billion..
Not sure how to read this spreadsheet

 

[beervoid]

Seems both under and over pitching can stimulate ester production. Gotta love brewing!

""When a cell is budding without enough oxygen, is when esters are produced.". Perhaps this could be the cause of the commonly held misconception that underpitching increases ester production? Underpitching promotes growth, which starts as aerobic growth (aerobic metabolic pathways are preferred over anaerobic ones) which consumes oxygen, thus forcing the yeast into budding without oxygen and producing esters. If underpitched beers are also under-oxygenated (which seems a plausible scenario) this could create the impression that underpitching results in estery beers. "

"
To complicate things even more... There is also evidence that heavy "over pitching" of yeast will produce similar higher esters to heavy "under pitching". The rational seems to be that fermentation finishes with less reproduction and a lower number of yeast generations. These earlier generations create more esters due to reduced energy toward reproduction, and are born into a higher sugar environment so they tend to flocculate in mass post fermentation rather than stay in suspension and clean up some remaining esters.

Plenty of disagreement out there over whether over pitching causes a beer to be cleaner or have more esters. My guess is that it is somewhat strain dependent."

Taken from: https://homebrew.stackexchange.com/questions/22989/pitching-rates-and-ester-formation

 

[Vale71]

Please do elaborate on the other means of increasing fruity esters.

Fermenter geometry is really important. Cylindroconical fermenters are the worst (if esters is what you aim for, that is). Shallow, large, square fermenters are best at promoting esters. Some old breweries haven't changed their fermenter geometry since forever for that very reason, even if they probably had to line them with stainless steel and cap them to prevent CO2 intoxication of the workforce due to updated health and safety regulations.

 

[beervoid]

Fermenter geometry is really important. Cylindroconical fermenters are the worst (if esters is what you aim for, that is). Shallow, large, square fermenters are best at promoting esters. Some old breweries haven't changed their fermenter geometry since forever for that very reason, even if they probably had to line them with stainless steel and cap them to prevent CO2 intoxication of the workforce due to updated health and safety regulations.

I ferment in corny kegs and had great esters so this doesnt seem to be the case here at least for the yeast I use.

 

[Miraculix]

Fermenter geometry is really important. Cylindroconical fermenters are the worst (if esters is what you aim for, that is). Shallow, large, square fermenters are best at promoting esters. Some old breweries haven't changed their fermenter geometry since forever for that very reason, even if they probably had to line them with stainless steel and cap them to prevent CO2 intoxication of the workforce due to updated health and safety regulations.

Why is that so?

 

[bierhaus15]

Can you elaborate on this?

Here is the spitballing, top of my head list of stuff for impacting esters (+/-). Basically all the stuff I had to memorize from Greg Casey's work. Look it up.

Yeast strain dependent - BAP2 gene and leucine uptake (+)
Ferment temp, higher (+) --> increasing temp towards end of fermentation with yeast flocculation (some yeasts) (+)
Pitch rate, lower (+)
Oygenation, higher (-)
Fermentation rousing (-)
High FAN/low unsaturated lipids (+) --> increase esters by addition of glucose or rice/sugar
Low FAN/high lipids (-) --> typical all malt worts (especially Euro malts)
Increased trub in fermentation (-)
Zinc (+)
Serial repitching (-)
Pitching in turbid wort (-)
Fermentation pressure (-)
High gravity wort (+) --> ethyl acetate
High maltose fermentations (-)
Undermodified malts (+)
High caramel malts (-)
Fermentation geometry

And my favorite two bits; propagating yeast in wort media high in glucose/fructose can increase ester development in subsequent generations. Also, "yeast are not indifferent to design and process change".... if a yeast is accustomed to a particular fermenter geometry/process and is then transferred to another fermentation environment, it will not behave the same nor produce the same fermentation flavor. Pretty much explains why all UK home brew strains never taste the same as the original, among other reasons. I worked at a brewery that went from shallow box fermenters to CCVs and flavor matching ale fermentations between the systems was nearly impossible. Courage struggled with this mightily for years.

Edit: Obviously, not all of these are better for total flavor quality.

 

[beervoid]

Found this one article quiet interesting. He is of the opinion that higher pitching rates encourage esters.
https://draymans.com/ester-production-in-yeast/

 

[Miraculix]

Found this one article quiet interesting. He is of the opinion that higher pitching rates encourage esters.
https://draymans.com/ester-production-in-yeast/

Ich Made once a starter with dry yeast, something American ale. It was fuuuull of esters.

The beer I used it in was clean.

 

[Northern_Brewer]

When thinking about pitch rate, it's not just about the esters produced by the yeast - although underpitching can have a dramatic effect - see this for the effect of underpitching US-05 on isoamyl acetate and ethyl hexanoate.

But on the following slide you'll see the effect of pitching on hop compounds - overpitching gives a particularly dramatic increase in geranyl isobutanoate and to a lesser extent myrcene and citronellol, but a decline in methyl geranate.

 

[beervoid]

When thinking about pitch rate, it's not just about the esters produced by the yeast - although underpitching can have a dramatic effect - see this for the effect of underpitching US-05 on isoamyl acetate and ethyl hexanoate.

But on the following slide you'll see the effect of pitching on hop compounds - overpitching gives a particularly dramatic increase in geranyl isobutanoate and to a lesser extent myrcene and citronellol, but a decline in methyl geranate.

Thanks for sharing that, fascinating stuff... was that from an australian conference?
I guess Methyl Geranate is Geraniol derived?

My next brew experiment has got to be an under-pitch vs over pitch now...