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Not sure which forum is best for this, but considering most ester formation is done in fermentation I'm putting it here.

Taken from here:
https://jameskennedymonash.wordpress.co ... ir-smells/" onclick="window.open(this.href);return false;" rel="nofollow

Actually, in distilling, most ester formation is done in the spirit. For instance, in bourbon, the sour mash process introduces a very large amount of lactic acid. During distillation, some ester is formed, but the bulk of it is during the aging process since the lactic acid is a very short-chain carboxylate and carries easily into the spirit.

*** Before you read the rest of this, as this is the internet, I want to clarify I'm not trying to be a jerk/troll/other unpleasantness.

Do we actually know where most esters are formed? Based on my rather weak understanding of the chemistry an ester can form when there is an acid and ethanol in solution, correct? In barrels there is tannic acid. That would create esters. Over time that would create a lot of them. Open fermentation also encourages ester fermentation over closed. In fermentation lactic acid can be produced by contamination with Lactobacilis. Lactic Acid's boiling point is 261. So would much if any get carried over? It says Lactic acid is hygroscopic, would that account for it getting carried over at lower temps (in the tails maybe)?

I'm not sure of the boiling point of most esters, so I can't say how they would get carried over either.

Is it a case of "it depends?"

Ester formation during aging:
https://istillblog.wordpress.com/2015/0 ... he-barrel/" onclick="window.open(this.href);return false;" rel="nofollow
https://www.bostonapothecary.com/barrel ... on-design/" onclick="window.open(this.href);return false;" rel="nofollow

Ester counts after single and double distilation: https://www.bostonapothecary.com/distil ... e-5-of-15/" onclick="window.open(this.href);return false;" rel="nofollow

I read this a long time ago, that's where I got the idea that most esters are formed in fermentation: http://whiskyscience.blogspot.com/2011/ ... vours.html" onclick="window.open(this.href);return false;" rel="nofollow

Open fermentation ester production:
https://homebrew.stackexchange.com/ques ... -increased" onclick="window.open(this.href);return false;" rel="nofollow
https://beerandbrewing.com/4-reasons-to ... mentation/" onclick="window.open(this.href);return false;" rel="nofollow

https://en.wikipedia.org/wiki/Lactic_acid" onclick="window.open(this.href);return false;" rel="nofollow - Lactic acid is hygroscopic. DL-lactic acid is miscible with water and with ethanol above its melting point which is around 17 or 18 °C. D-lactic acid and L-lactic acid have a higher melting point.

https://en.wikipedia.org/wiki/Hygroscopy" onclick="window.open(this.href);return false;" rel="nofollow

As I read this over maybe it's a stacking effect - Some are made in fermentation, some in the still, some in the barrel.

excellent information just tried head treatment with lemon juice and air it lets see what happens.

PapaPro

Single Malt Yinzer wrote: Lactic Acid's boiling point is 261. So would much if any get carried over? It says Lactic acid is hygroscopic, would that account for it getting carried over at lower temps (in the tails maybe)?

I'm not sure of the boiling point of most esters, so I can't say how they would get carried over either.

Everything you can smell will get carried over. Because you can smell it only, if it is volatile in this situation (for example the ethanol concentration). Can you smell lactic acid? If yes, then it will get carried over.

Of course there also substances which get carried over without smell. Water for example. Simply because we are not able to smell them.

For example when I look at wikipedia ethyl butyrate:
Ethyl butyrate is one of the most common chemicals used in flavors and fragrances. It can be used in a variety of flavors: orange (most common), cherry, pineapple, mango, guava, bubblegum, peach, apricot, fig, and plum.
So it is obviously very volatile. But the boiling point is 120°C!
We think the boiling point and the volatility is the same. No. It's obviously not. The boiling point is defined at what temp pure ethyl butyrate boils. And this is so far away from distilling spirits, where we have mainly water and ethanol and only very little amounts of each ester.
There must be other factors deciding what gets carried over. Probably the concentration compared to for example water and ethanol.
The problem is, we think mainly about water and ethanol. Those substances we have in a high concentration and we can see a logical relation between the two boiling points and the process of a distillation. Ethanol has a lower boiling point, so it gets over "first". That's true. But this logical relation, the effect of the boiling point of the pure substance, seems to be outmatched by other factors when it is mixed with other substances and the concentration is low.

Another factor is the odor threshhold. Even very small amounts of an ester are enough to smell it.