Esters: A reading list to understanding them better

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Esters: A reading list to understanding them better

Postby Single Malt Yinzer » Mon Jul 10, 2017 5:04 am

I will add to this list but here are some key ones to help you understand what esters are, their importance in flavor development, and how to increase their production in the fermenting, distilling, and aging processes.

In short an ester is a molecule of alcohol "fused" with a fatty acid. Esters can create complex flavor profiles and can be detected at very low levels - a few PPM (parts per million). They can also introduce flavors of constituent materials that are not actually present (bananas, cherries, cloves, etc). They are generally products of enzymatic activity and therefor their production can be encouraged or discouraged by changing the conditions and materials used in the fermenting, distilling, and aging processes.

https://www.gastrograph.com/blogs/gastr ... ation.html
http://aem.asm.org/content/74/2/454.full
http://draymans.com/ester-production-in-yeast/
http://www.professorbeer.com/articles/esters.html
http://sourbeerblog.com/understanding-esterification/ <- Contains chart of acids and esters they form
https://ucanr.edu/repositoryfiles/Oberh ... -92483.pdf <- Wine based, but show a chart of Ester formation over time
http://www.scielo.br/scielo.php?script= ... 1000200012 <- Esters are in the highest concentrations in the heads, much less in the hearts, non in the tails.
https://sciencebrewer.wordpress.com/2013/04/ <- Chart showing how to enhance or decrease ester formation
http://cocktailwonk.com/2015/04/from-al ... aging.html
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Re: Esters: A reading list to understanding them better

Postby kiwi Bruce » Sat Jul 15, 2017 12:39 pm

Good post Single Malt Yinzer...I'm still working my way through the links, but very interesting so far.
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Re: Esters: A reading list to understanding them better

Postby Single Malt Yinzer » Thu Aug 03, 2017 6:22 pm

I can't seem to edit my original post so I will update it here:
"In short an ester is a molecule of alcohol "fused" with a carboxylic or fatty acid"

Warning: Very heavy science/chemistry.
Here's a link to a bunch of videos on Caboxylic acids and esterification. https://www.khanacademy.org/science/org ... erivatives
Here's one specifically on Fisher Esterification: https://www.khanacademy.org/science/org ... rification
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Re: Esters: A reading list to understanding them better

Postby OtisT » Thu Aug 03, 2017 7:46 pm

Hi. Here are two links to add to the list on esters.

From: Artisan Spirit magazine ( spring and Summer 2017 )
Article: Toasting my Spirits

Part 1 - The Chemistry
https://issuu.com/artisanspiritmag/docs ... 018_web/98

Part 2 - The Maillard reaction and distilled spirits production
https://issuu.com/artisanspiritmag/docs ... 64?ff=true
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Re: Esters: A reading list to understanding them better

Postby Single Malt Yinzer » Fri Aug 04, 2017 9:09 am

Thanks OtisT.

Seriously I never thought that I would end up learning so much chemistry in order to make booze. :thumbup:
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Re: Esters: A reading list to understanding them better

Postby RedwoodHillBilly » Fri Aug 04, 2017 11:33 am

Single Malt Yinzer wrote:Thanks OtisT.

Seriously I never thought that I would end up learning so much chemistry in order to make booze. :thumbup:


Well, when you think about it, we aren't doing things much differently than a pharma company is. We are using organic precursors to create some compounds (mashing), then running a reaction in a bio-reactor to make a different compound (fermenting), and finally purifying the product (distilling) to get the final drug (ethanol).
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Re: Esters: A reading list to understanding them better

Postby OtisT » Sat Aug 05, 2017 8:34 am

RedwoodHillBilly wrote:
Single Malt Yinzer wrote:Thanks OtisT.

Seriously I never thought that I would end up learning so much chemistry in order to make booze. :thumbup:


Well, when you think about it, we aren't doing things much differently than a pharma company is. We are using organic precursors to create some compounds (mashing), then running a reaction in a bio-reactor to make a different compound (fermenting), and finally purifying the product (distilling) to get the final drug (ethanol).


Ya, I helped build a half billion dollar pharma plant from scratch in Ohio. It's not much different! ;-)
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Re: Esters: A reading list to understanding them better

Postby Single Malt Yinzer » Fri Aug 11, 2017 4:27 pm

One more change - "They are generally products of enzymatic activity" - Not true - It is purely a chemical reaction.

New item: Proteolysis (We know this better as the protein rest for grain based mashes)- https://en.wikipedia.org/wiki/Proteolysis

Proteolysis is the breakdown of proteins into smaller polypeptides or amino acids. The rate of proteolysis can be significantly increased by extremes of pH and heat.


Those amino acids include carboxylic acids: https://en.wikipedia.org/wiki/Carboxylic_acid

Carboxylic acids occur widely and include the amino acids (which make up proteins) and acetic acid (which is part of vinegar and occurs in metabolism).


Carboxylic acid is one of three components of an ester along with alcohol and a catalytic acid.

Know I am wondering how important protein rests are in ester development. Given up to now I've only been doing saccharification rests (single step conversion). I think I'll start doing protein rests now to see what effect had on flavor development.

http://blog.eckraus.com/how-to-do-a-protein-rest
John Palmer points out that “using a protein rest on fully modified malts tends to remove most of the body of a beer, leaving it thin and watery.”


As a distiller this shows that the brewing process for us is different as we're aiming for different goals. Our saccharification is at a lower temp to produce the most fermentable sugars and it looks like the protein rest seems to be something we would want to do in order to produce the most carboxylic (amino) acids. Distillers we do not want to have unfermentable sugars in the wort nor do we care about the body of the beer. Neither ends up carrying over to the distillate.
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Re: Esters: A reading list to understanding them better

Postby RedwoodHillBilly » Fri Aug 11, 2017 9:18 pm

Single Malt Yinzer wrote:
Know I am wondering how important protein rests are in ester development. Given up to now I've only been doing saccharification rests (single step conversion). I think I'll start doing protein rests now to see what effect had on flavor development.

As a distiller this shows that the brewing process for us is different as we're aiming for different goals. Our saccharification is at a lower temp to produce the most fermentable sugars and it looks like the protein rest seems to be something we would want to do in order to produce the most carboxylic (amino) acids.


Interesting, I would be interested in the results of your experiments. I don't do protein rests, but do use beta glucan enzymes. I will have to do some research into carboxylic acid production vis-a-vis protein rests and enzymes.
John Barleycorn must die.
"and little Sir John and the nut brown bowl proved the strongest man at last.
The huntsman he can't hunt the fox, nor so loudly to blow his horn
and the tinker he can't mend kettle nor pots without a little barleycorn."
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Re: Esters: A reading list to understanding them better

Postby kiwi Bruce » Sat Aug 12, 2017 10:51 am

She blinded me with Science !

Blinded.jpg


https://www.youtube.com/watch?v=-FIMvSp01C8
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Re: Esters: A reading list to understanding them better

Postby Single Malt Yinzer » Sun Aug 13, 2017 3:38 pm

Thanks guys. Looks like it is limited to unmalted or not fully modified (malted) grains: http://howtobrew.com/book/section-3/how ... dification

The two main proteolytic enzymes responsible are peptidase and protease. Peptidase works to provide the wort with amino acid nutrients that will be used by the yeast. Protease works to break up the larger proteins which enhances the head retention of beer and reduces haze. Fully-modified malts have already made use of these enzymes and do not benefit from more time spent in the protein rest regime.


Peptidase seems interesting. It appears to be the enzyme that creates amino (carboxylic) acids. I'll start looking at that one now.
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Re: Esters: A reading list to understanding them better

Postby Single Malt Yinzer » Thu Aug 17, 2017 6:13 pm

YEAST AND ITS EFFECT ON THE FLAVOUR OF ALCOHOLIC BEVERAGES
http://onlinelibrary.wiley.com/doi/10.1 ... 370.x/epdf

This paper covers the different fatty acids made by different strains of yeast and the esters that form from them.

Sensory examination of an aroma model consisting of alcohols, fatty acids,
esters and aldehydes, in concentrations estimated in whisky, has proved that—
in addition to vicinal diketones—esters predominate as components influencing
the aroma, but also some fatty acids exercise most marked influence. Further
more, some people possess good ability to smell certain compounds whereas
others cannot smell them as well, but detect other compounds more easily.


As a side note I'm naming my next band the Vicinal Diketones.
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