High Value Congeners

[bostonapothecary]

Hi all, I started this topic as a catchall for conversations on all the high value congeners chased when producing rum. HVC's includes esters, noble acetals, noble volatile acidity, and what ever rum oil is (rose ketones and goodness knows what else). There is room to talk about harmony, philosophy, and how the fate of everything high value is bound to fusel oil.

I thought I would kick off the topic by sharing two French translations I just put up from 1975. The first paper, Qualitative And Quantitative Study Of Volatile Constituents Of Rum, is fascinating. They start inspired by Karl Micko who was the father of the 8 fraction birectifier method:

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We therefore investigated whether it was possible to identify characteristic constituents within other categories of substances, and in particular among secondary alcohols and phenols. In addition, our work focused on the identification of a very characteristic constituent of rums, inspired by the work done at the beginning of this century by MICKO (1908).

They work their way to a rose ketone connection and give us a rum oil smoking gun:

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Trans β-damascenone has been identified in a large number of products of plant origin and we have just discovered a trace in Cognac.

It appears to be more abundant in the grand arôme rums than in other types of rums, suggesting that it might form during alcoholic fermentation, as reported by MICKO about what he called rum oil.

 

This paper also contains very unique sensory details because they used GC-Olfactometry:

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This very simple methodology makes it possible to obtain extracts that are very concentrated and, it seems, very significant, highly concentrated, because type B extracts are low in higher alcohols, heavy esters and acetals. Very significant, because the extracts of type A have an aroma reminiscent of that of Cognac when the rum studied is rich in esters, and an aroma reminiscent of Calvados when acetals dominate. On the other hand, in all cases, the extracts of type B have an aroma very close to that of the rum of departure, with its qualities and its defects.

What they perform is a bit exotic and startlingly expensive. A lot of the same organoleptic insights can be obtained from the birectifier method. I'm drawn to the comment about Calvados and acetals dominating. I've yet to do a Calvados birectifier case study.

The next paper, The Position Of Rhum In The Context Of Spirits In General, is quite unique and raises a lot of questions. They spend quite a bit of time on Damascenone, but also TDN (petrol in reisling) and TTN (not familiar with). What other readers may be most interested in is the unique ester data tables with extraordinary samples:

The first question raised by me is don't you think a whiskey would have more ethyl lactate?  And then secondly, why do they have a column for isoamyl acetate for rum, but not for the other spirit categories?

[JustAndy]

I haven't read the paper totally, so I don't know why they didn't find it but there are many references to ethyl lactate in whisky, and a couple of papers showing the average level



https://books.google.com/books?id=allg4XxlOM4C&pg=PA200&lpg=PA200&dq=ethyl+lactate+whisky&source=bl&ots=Pgc5DIetjS&sig=ACfU3U37z83LZgOZy3dXVrAlvyMbkTo8Gw&hl=en&sa=X&ved=2ahUKEwjCvpiW9YzgAhX-CDQIHTECAcAQ6AEwBHoECAAQAQ#v=onepage&q=ethyl lactate whisky&f=false

[Silk City Distillers]

Have you considered adding damascenone to a sample of fairly pedestrian rum?  Maybe a quick and dirty blind tasting.

I've done this myself with many other esters.  It's fairly insightful, or at least helps establish a sort of confirmation of the relative importance of a component.

I see that Aldrich has small samples available for $40, relatively cheap test.

 

[Silk City Distillers]

I would imagine, with a set of reference compounds, you could run trials to establish exactly where in your  birectifier fractions specific constituents would fall.

You could pair that with reference samples of these compounds, and it would be a very interesting organoleptic tool.

For example, just making things up, if damascenone falls in fraction X, you could do a test birectifier distillation, check fraction X against a sample of damascenone, and establish not only presence, but an idea of rough quantity.  It would take some significant legwork to run all the test distillations (ethyl alcohol+Compound).

A nice set of references - positives and faults, would build out a very nice little analytical kit.

[Foreshot]

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General description

Damascenone is a norisoprenoid ketone mainly found in red wines.^[7] It occurs naturally in tomato^[1] and grapes.

https://www.sigmaaldrich.com/catalog/product/aldrich/w342017

Huh. My partner is obsessed with doing a tomato brandy. I think it could be interesting based on that. His test batches so far have been interesting.

Side note - there's a bunch of reference papers at the bottom of the page.

[bostonapothecary]

1 hour ago, Silk City Distillers said:

Have you considered adding damascenone to a sample of fairly pedestrian rum?  Maybe a quick and dirty blind tasting.

I've done this myself with many other esters.  It's fairly insightful, or at least helps establish a sort of confirmation of the relative importance of a component.

I see that Aldrich has small samples available for $40, relatively cheap test.

 

I'm itching to get reference for all the rose ketones and play with them. I wrote a post called Sensory Sketches for Apprentices where you take fractions and systematically add them to a whole distillate to see how they impact the sensory matrix. It takes a time investment, but you can learn a ton.

[bostonapothecary]

1 hour ago, Silk City Distillers said:

I would imagine, with a set of reference compounds, you could run trials to establish exactly where in your  birectifier fractions specific constituents would fall.

You could pair that with reference samples of these compounds, and it would be a very interesting organoleptic tool.

For example, just making things up, if damascenone falls in fraction X, you could do a test birectifier distillation, check fraction X against a sample of damascenone, and establish not only presence, but an idea of rough quantity.  It would take some significant legwork to run all the test distillations (ethyl alcohol+Compound).

A nice set of references - positives and faults, would build out a very nice little analytical kit.

I'm hoping that if we finish the birectifier automation kit, we can create case studies for a bunch of distillations with isolated esters to see what happens. Something I'm really curious about is the place of the odder acetals and what they feel like organoleptically.

Damascenone has the potential to be everywhere carotene is, but it may not be too important until it is at levels where its radiant sensory properties emerge (to borrow a word the perfumers use). I think the best way to sum up radiance is that it increases the threshold of perception of ethanol, making a spirit feel more mellow while decreasing the threshold of perception of other odorants, like esters, making them seem more intense. It also dramatically increases persistence. Specialty GCMS studies find it everywhere in trace quantities, but if it isn't easily observable with a low resolution tool like the birectifier, it may not be too important.

[bostonapothecary]

1 hour ago, Foreshot said:

https://www.sigmaaldrich.com/catalog/product/aldrich/w342017

Huh. My partner is obsessed with doing a tomato brandy. I think it could be interesting based on that. His test batches so far have been interesting.

Side note - there's a bunch of reference papers at the bottom of the page.

"How low pH can intensify beta-damascenone and dimethyl trisulfide production through beer aging." This is the paper, I'm going to grab first. One thing that sets rum apart from other spirits, is sometimes have a wildly low pH, like vinegar process rums that Hampden makes, and also the long resting periods where these compounds may form by what the beer industry called "staling". When you maximize the multiple channels of formation, something very special may happen.

Tomato brandy has some cool theoretical potential, so does carrot.