High Ester Still Build

Smaug

@punkin said: It's hardly new....

Sure, sure.
But the term is not a common term. Should be.

I'm going to use it once or twice every other sentence just to give it a foothold.

Thermal degradation, and thermal degradation...

grim

Well at the extreme, yeah, but for lots of temperature sensitive flavor compounds, they can easily break down with heat exposure. That’s why the delicate fresh herbs go in at the end of making sauce.

It’s not a clear cut universal better/worse though. The wonderful Maillard reaction relies on thermal decomposition too.

grim

@SingleMaltYinzer

You mentioned something a couple posts back that I think is important. Many of the fantastic aroma/ester precursors exist in the tails and stillage.

Heavier alcohols, and acids, all live back here.

But the esters we want, they are all volatile and come off mainly earlier in the distillation, but they do smear across.

How do you get these acids and alcohols, that have higher boiling points and are less volatile, and put them into an environment that has perhaps less water, or gives them more of an opportunity to react, to form the more volatile ester, which can then get whisked away through the still.

Smaug

@grim said: SingleMaltYinzer

You mentioned something a couple posts back that I think is important. Many of the fantastic aroma/ester precursors exist in the tails and stillage.

Heavier alcohols, and acids, all live back here.

But the esters we want, they are all volatile and come off mainly earlier in the distillation, but they do smear across.

How do you get these acids and alcohols, that have higher boiling points and are less volatile, and put them into an environment that has perhaps less water, or gives them more of an opportunity to react, to form the more volatile ester, which can then get whisked away through the still.

Ooh pick me (raises hand).

By pulling product off as liquid (LM) while simultaneously maintaining liquid beds with the higher volatiles above the take off port.

grim

We know extended duration under high reflux aids ester formation.

That would let you run high levels of reflux, maintain a low water environment, while allowing a lower take off proof, because you are pulling product at a lower plate.

I never really thought about that in that way. Usually with long periods of high reflux, you are forced into very high take off proofs. Without the ability to take off as a side-stream, you don’t have much choice otherwise.

SingleMaltYinzer

@grim said: How do you get these acids and alcohols, that have higher boiling points and are less volatile, and put them into an environment that has perhaps less water, or gives them more of an opportunity to react, to form the more volatile ester, which can then get whisked away through the still.

So (I think) part of that is direct steam heating with stillage versus water. You're pushing excess precursors into wash encouraging ester formation. Once that ester is formed, as you said, it will have a lower boiling point and skedaddle out of the kettle. You also have the oleophilic nature of alcohol. I believe it pulls some fatty acids and lipids into vapor before their boiling point as it does with water.

@Smaug said: By pulling product off as liquid (LM) while simultaneously maintaining liquid beds with the higher volatiles above the take off port.

Now I need a 10' tall thumper with LM instead of a condenser. You know I'm a sucker for crazy stuff. I'll admit not having researched LM stuff much. I think of it being more for neutrals so it wasn't something I put time into.

Smaug

Super simple and allows for take off at any plate level.

SingleMaltYinzer

That's interesting. I don't think I've seen a short stack continuous like that before.

Smaug

In Kentucky they'd call it a Bourbon still.
Conceptually, it is the exact same design as Stumpy's prototype.

Smaug

An pull from any plate really. Though this one is set up to pull from 4 & 6.

Can adjust flow control to bleed off heads or send everything back to the plates to be collected like an Armagnac.

Smaug

I only bring up Armagnac because of the aromatic qualities.

grim

Is it wrong to call it cute?

grim

The design has certainly gotten more elegant as well.

grim

Are you bleeding off heads as vapor?

Smaug

@grim said: Are you bleeding off heads as vapor?

Yessir. Ideally a heads drip rate for this diameter about 1 drop per second.

There is a dedicated heads condenser that does require a dedicated cooling circuit.

DonMateo

I love this thread.

All of you guys have more experience with me but I will say I have been using @zymurgybob's old style pot stilling method and in the spirit run I have been taking a short heads cut and going down to 30% at full power before backing off and taking off the remaining ethanol.

My whiskys end up having some nice complex flavors as well as great esters, depending on what yeast I use.

I want to have a deep bed, ie 450m deep bubble cap with a dephlegmator on it to try and get all of those deep compounds to come over at higher temps.

SingleMaltYinzer

So thinking about this a little more I never set the parameters and assumptions of what I want to do or what I want to use:

• This will be for whiskeys and rums.
• Neither source materials have significant flavor contributions from esters (that I am aware of).
• Ester & precursor production is mostly from yeast, distilling, and aging.
• Grains, mostly malted barley, have proteins that through pyrolysis (malting, mashing) that breakdown into carboxylic acids (mostly fatty acids) that increase the chemical diversity of the wash.
• Rum is mostly sugars with much less protein/amino acid contribution.
• Ester production by yeast is mostly via enzymatic action. Unless the cell wall is broken those esters do not become a significant part of the wash.
• Most ester production in the distilling and aging processes is done via Fischer Esterification - the catalytic action of acids.

Breakdown of flavor contribution in different barley varieties:

Comprehensive Analysis of Different Contemporary Barley Genotypes Enhances and Expands the Scope of Barley Contributions to Beer Flavor @ Taylor & Francis Online (see table 4)

Tons of fatty acids, some esters, mostly ethyl acetate.

My plan is to do long rum style ferments. I want the yeast to make a ton of precursors, autolyse, and release esters also. Then in the distilling and aging steps set the conditions for maximum ester formation. For the distilling part I need to get the deep tails to mix with more of the heads and hearts - similar to the Cousins process. I think the 3 chamber still is a somewhat reverse version of the Cousins twin retort process. The idea is the same, mix the very late tails with the heads/hearts. I don't believe the TTB would approve the use of the Cousins process (chemical extraction of tails and re-introduction) and allow me to call it whiskey. That would be a marketing problem. Using a thumper would be OK though.

grim

Couple of things.

The types and amounts of proteins in the wash will influence the fusel alcohols created by yeast. Increases in amino acids generally result in increases in fusel acid and alcohol production (aka Ehrlich Pathway). Iso/Leucine and Valine are two very important ones, as they will form Iso/Amyl Alcohol and Isobutanol respectively. Two main fusel alcohols, and two alcohols that are important in ester complexity. Considering rum for example, this is a major factor between the flavor profile of crystallized sugar rums vs. molasses rums. To take this a step further, molasses also contains a number of long-chain carboxylic acids that crystal sugar does not. On the grain side, unmalted grain tends to have far less amino acid, meaning the end result is lower in fusel alcohol and the corresponding esters.

I don't think you can say generally, that most ester production is due to Fischer vs. biological. At least up to the start of aging. Clearly this doesn't apply to techniques like the Cousins process, which border on chemical engineering.

In terms of high-ester rum distillation, the literature indicates that many of these rums were distilled with either all, or some portion of the yeast, which would allow for both ester and acid availability during distillation. Again, this is a big factor in distinctive flavor profiles of rum.

grim

On the amino acid contribution (malt and molasses vs. raw grain and crystal sugar), here is a great table from Brewing with Unmalted Cereal Adjuncts: Sensory and Analytical Impacts on Beer Quality by Yorke, Cook, and Ford.

Don't pay too much attention to every individual line item, but more the general trend. Less nutrient as amino acids, the less fusel and ester generated. You want to make clean alcohol? Don't use malt, use raw grain+enzyme, and supplement nutrient with a non-amino source like DAP. Want esters? More malt, more molasses, and focus on using amino-based nutrients (aka, not-DAP).

SingleMaltYinzer

@grim said: I don't think you can say generally, that most ester production is due to Fischer vs. biological. At least up to the start of aging. Clearly this doesn't apply to techniques like the Cousins process, which border on chemical engineering.

I agree that there isn't anything I've seen that attributes the source of esters to one or the other. Yeast do create them as step in making sterols to build cell walls during growth phase. I guess we would have to analyze the makeup of the wash/spirit from start to finish to see what is being made and the most likely cause.

@grim said: To take this a step further, molasses also contains a number of long-chain carboxylic acids that crystal sugar does not.

That I was not aware of. A quick google yielded this:

PROCESS FOR RECOVERING CARBOXYLIC ACIDS FROM SUGAR CANE INDUSTRY BY-PRODUCTS (PDF)

And from that this little gem: "recovery of carboxylic acids from molasses was impossible due to their high viscosity." Moral of the story: Everyone hates working with molasses. From an economic standpoint it was too costly to extract carboxylic acids from molasses. That doesn't effect distillers as we use the molasses and the carboxylic acids come with it.

grim

Molasses also contains linoleic, palmitic, oleic and linolenic acids - as does grain.

Check this one for a good overview:

Transcriptional Comparison Investigating the Influence of the Addition of Unsaturated Fatty Acids on Aroma Compounds During Alcoholic Fermentation @ frontiers in Microbiology

Smaug

Oleic acid seems a non factor with respect to aromatic qualities. Wiki characterizes as odorless. Not sure how the linoleic and palmitic otherwise play into the rhum/rum aromatic equation?

grim

Indirect, read through the intro paragraph on that last link.

Long chain fatty acids = long chain carboxylic acids = unsaturated fatty acids (UFA).

SingleMaltYinzer

Oleic Acid has 18 carbons. Most ester charts stop at 10 carbons so I'm not sure what esters (or associated aromatic/flavor) it would make.

grim

Biodiesel

Smaug

@grim said: Biodiesel

Omg! So delish.....

SingleMaltYinzer

Sure know how to kill the romance, don't ya? (ha)

grim

God honest truth, ethyl esters of long chain fatty acids are biodiesel. Usually it’s methyl alcohol, because it’s cheaper, so this here would be fancy diesel.

Keep in mind though, the concentrations here are tiny. Either way, they won’t kill you, ethyl oleate is used as a carrier for steroid injections.

All fun aside, look into the papers that talk about the impact of long chain acids in aroma and flavor formation in yeast. Too little is bad, and too much is bad. Usually, a little more than you have will yield a positive impact - this includes all manner of ester formation. Call it a modulator maybe?

I think the increased long chain acids are a big part of the story of why molasses rums taste different from cane juice (lower concentration) or crystal sugar rums (none at all).

Some of the old Jamaican texts talk about including cane fats and waxes in the ferment. This would be to directly increase the amount of these long chain acids.

The long chain esters themselves, they smell faintly floral, buttery, dairy, creamy, oily - they are all delicate in comparison to something like ethyl acetate, which is smack you in the face nail polish remover.

Themselves, they are oily, could potentially contribute to mouthfeel, finish, and flavor persistence

grim

Coconut oil, for example, would be an interesting addition to crystal sugar rums. Not because it will add any coconut flavor at all, but because it will add in all of these interesting fatty acids in a way that's "biofamiliar". I made that last word up, but in a way that's inline with how they would exist in nature for the most part.

MokumMoonshine

I have family recipies for indonesian rum called Arak. One of the ingredients is dried coconut. For several years I made a rum that was appreciated by the cocktail bar community in Amsterdam. It works great, and nobody knew!