Esters: A reading list to understanding them better

[Single Malt Yinzer]

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" onclick="window.open(this.href);return false;" rel="nofollow
http://aem.asm.org/content/74/2/454.full" onclick="window.open(this.href);return false;" rel="nofollow
http://draymans.com/ester-production-in-yeast/" onclick="window.open(this.href);return false;" rel="nofollow
http://www.professorbeer.com/articles/esters.html" onclick="window.open(this.href);return false;" rel="nofollow
http://sourbeerblog.com/understanding-esterification/" onclick="window.open(this.href);return false;" rel="nofollow <- Contains chart of acids and esters they form
https://ucanr.edu/repositoryfiles/Oberh ... -92483.pdf" onclick="window.open(this.href);return false;" rel="nofollow <- Wine based, but show a chart of Ester formation over time
http://www.scielo.br/scielo.php?script= ... 1000200012" onclick="window.open(this.href);return false;" rel="nofollow <- Esters are in the highest concentrations in the heads, much less in the hearts, non in the tails.
https://sciencebrewer.wordpress.com/2013/04/" onclick="window.open(this.href);return false;" rel="nofollow <- Chart showing how to enhance or decrease ester formation
http://cocktailwonk.com/2015/04/from-al ... aging.html" onclick="window.open(this.href);return false;" rel="nofollow

[kiwi Bruce]

Good post Single Malt Yinzer...I'm still working my way through the links, but very interesting so far.

[Single Malt Yinzer]

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" onclick="window.open(this.href);return false;" rel="nofollow
Here's one specifically on Fisher Esterification: https://www.khanacademy.org/science/org ... rification" onclick="window.open(this.href);return false;" rel="nofollow

[OtisT]

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" onclick="window.open(this.href);return false;" rel="nofollow

Part 2 - The Maillard reaction and distilled spirits production
https://issuu.com/artisanspiritmag/docs ... 64?ff=true" onclick="window.open(this.href);return false;" rel="nofollow

[Single Malt Yinzer]

Thanks OtisT.

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

[RedwoodHillBilly]

Thanks OtisT.

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

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).

[OtisT]

Thanks OtisT.

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

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!

[Single Malt Yinzer]

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" onclick="window.open(this.href);return false;" rel="nofollow

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" onclick="window.open(this.href);return false;" rel="nofollow

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" onclick="window.open(this.href);return false;" rel="nofollow

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.

[RedwoodHillBilly]

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.

[kiwi Bruce]

She blinded me with Science !

https://www.youtube.com/watch?v=-FIMvSp01C8" onclick="window.open(this.href);return false;" rel="nofollow

[Single Malt Yinzer]

Thanks guys. Looks like it is limited to unmalted or not fully modified (malted) grains: http://howtobrew.com/book/section-3/how ... dification" onclick="window.open(this.href);return false;" rel="nofollow

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.

[Single Malt Yinzer]

YEAST AND ITS EFFECT ON THE FLAVOUR OF ALCOHOLIC BEVERAGES
http://onlinelibrary.wiley.com/doi/10.1 ... 370.x/epdf" onclick="window.open(this.href);return false;" rel="nofollow

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.

[Single Malt Yinzer]

I've put all my research into this wiki entry: http://homedistiller.org/wiki/index.php/Ester" onclick="window.open(this.href);return false;" rel="nofollow

It contains many corrections. It also has a list of ways to increase or decrease esters in your product.

[kiwi Bruce]

That is a tremendous effort S.M.Y. and I for one, appreciate what you have done...very good job ! ! !

[Single Malt Yinzer]

Thanks Bruce. I bought a book "Reactions" by Peter Atkins. I was told it explains esterification really well. Hopefully it will help even more.

[Single Malt Yinzer]

"Effects of fermentation temperature and Saccharomyces species on the cell fatty acid composition and presence of volatile compounds in wine"

https://pdfs.semanticscholar.org/b02e/5 ... 454d1e.pdf" onclick="window.open(this.href);return false;" rel="nofollow

Furthermore, the fatty acid composition of the medium also depends on the fermentation conditions, i. e., oxygen availability, as a result of yeast metabolism. So, when the fermentation is carried out in anaerobic conditions, medium-chain fatty acids are always produced (Hammond, 1993; Ravaglia and Delfini, 1993). In contrast, when the fermentation is carried out in aerobic or semi-aerobic conditions, fewer medium-chain fatty acids and more unsaturated fatty acids are produced (Suomalainen and Lehtonen, 1979). Fatty acids and their esters have an essential role in alcoholic fermentation (Larue et al., 1984). In fact, it has been shown that hexanoic, octanoic, decanoic and dodecanoic acids and their esters, together with ethanol, can inhibit the growth of yeast (Geneix et al., 1984; Ravaglia and Delfini, 1993). Long-chain fatty acids, on the other hand, seem to have a positive action (Soufleros and Bertrand, 1988).

Medium and long chain fatty acids increase esters, unsaturated fatty acids decrease esters

[Runt]

Good post Single Malt Yinzer...I'm still working my way through the links, but very interesting so far.

+1 It will take me a month to read all these links.

[Runt]

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.

I disagree to a point.
A sweet wort shows up in the flavor of the spirit.
Body I believe has some kind of effect on the spirit as well.

[ShineonCrazyDiamond]

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.

I disagree to a point.
A sweet wort shows up in the flavor of the spirit.
Body I believe has some kind of effect on the spirit as well.

This has been my hands on experience, too, and I tell people all the time. It shows up in the distillate flavor, and adds to the body. No amount of books and papers will teach me more than experimental experience.

[Saltbush Bill]

No amount of books and papers will teach me more than experimental experience.

Its a shame that not all seem to understand that , some seem to just spout endless theory, while at the same time having very little practical experience.

[Hügelwilli]

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.

I disagree to a point.
A sweet wort shows up in the flavor of the spirit.
Body I believe has some kind of effect on the spirit as well.

This has been my hands on experience, too, and I tell people all the time. It shows up in the distillate flavor, and adds to the body. No amount of books and papers will teach me more than experimental experience.

If a sweet wash gives a better distillate, why not adding sugar to the dry wash directly before distillation? Anyone tried this? Or did someone other experiments, perhaps someone has a link for me?

[Tummydoc]

Unfermentable sugars lead to body and residual sweetness/malt flavor in beer. You wont get that adding sucrose prior to distillation. Haven't tried it, but think you'd waste the sugar.

[Hügelwilli]

It wasn't meant serious.
There are starch, large unfermentable sugars and small fermentable sugars.
Starch gives sliminess to a beer. But does it give sliminess to a distilate? Of course not. Otherwise UJSSM or sweetfeed whiskey were undrinkable.
Fermentable sugars give a sweet taste to beer. But does it give a sweet taste to a distillate? Probably not. I didn't try.
But the thing between, unfermentable sugars, suddenly have a magic, what lets them get carried over into the distillate?
My opinion ist: If the story of the added mouthfeel by unfermentable sugars is true, there must be a different reason for that. If. I have read different opinions about this.

[Runt]

No amount of books and papers will teach me more than experimental experience.

Its a shame that not all seem to understand that , some seem to just spout endless theory, while at the same time having very little practical experience.

It sounds like some people know more theory because they are lucky if they make 1 run a year.
I learned a lot being able to make run after run after run year round, I think that makes me lucky.

Hugelwilli If You added sugar right before distilling, I would think You would want to referment it after it comes back out of the still as to not waste Your money. I think they do something similar with sour mash refermenting it multiple times?
Sweetness weather fermentable or not can carry over into the spirit in my experiences.

[cayars]

I've not tried anything like this, but by adding a tad bit of sugar to the boiler you might get some maillard reaction from it that would change taste a bit.

[BoomTown]

Boy I wish I could review this whole record. It’s lost to me because it’s mostly outside my 12 month window.

[Hügelwilli]

It wasn't meant serious.
There are starch, large unfermentable sugars and small fermentable sugars.
Starch gives sliminess to a beer. But does it give sliminess to a distilate? Of course not. Otherwise UJSSM or sweetfeed whiskey were undrinkable.
Fermentable Unfermentable sugars give a sweet taste to beer. But does it give a sweet taste to a distillate? Probably not. I didn't try.
But the thing between, unfermentable sugars, suddenly have a magic, what lets them get carried over into the distillate?
My opinion ist: If the story of the added mouthfeel by unfermentable sugars is true, there must be a different reason for that. If. I have read different opinions about this.

Can't edit it anymore of course what I wrote a half year ago. The topic came up again today, I recognized my mistake and want to correct it.