My favorite raspberry liqueur is the Pacific Rim framboise originally from Bonny Doon, but now produced independently. Their raspberries are an heirloom cultivar specifically selected for aroma. The liqueur has the structure of a high acid dessert wine and is far less sweet and more skewed toward acid than other liqueurs. I’ve relied upon it for years in carbonated cocktails. A fermented raspberry wine is produced which is ultimately sugared and fortified to 16.5% ABV. I’m not sure how the raspberries are ameliorated if at all before fermentation.
Besides looking for the usual what aroma goes where and what it all feels like organolepticaly, I was hunting for Damascenone. In all this Damascenone rum oil nonsense it is hard to understand what is a meaningful amount, such as found in a heavy bodied rum, and what is just technically there if you use exotic analysis like chromatography.
After isolating Damascenone in Bulgarian rose oil, back in 1971, perfume research scientists went on to isolate it in Burley tobacco oil and then again in raspberry oil. So, would we find a meaningful amount in an exemplary raspberry liqueur? Only one way to find out and hopefully learn other things along the way.
Damascenone in many cases is thought to reside mostly in the essential oil and not always freely in the original substrate because it is released by processing often with heat. The raspberry liqueur was likely never heated during production, but would be by laboratory distillation. When many people are finding very trace amounts it may be merely as an artifact of their laboratory processing. Trace amounts are thought to matter because of the startlingly low threshold of perception, but exactly how much matters is an open question. My hunch is that rums that exhibit the bouquet of rum oil in the form of damascenone have abnormal & extraordinary amounts, far beyond other spirits. A 1980’s Japanese Study found four times more in an exemplary rum (Rhum Negrita) than in a premium single malt, bourbon, or Cognac. The literature makes it seem like damascenone is everywhere, but on my own breath, I want to blow a 0.41 (see the last entry on the chart).
A unique route damascenone may turn up in this particular raspberry liqueur is because it has been staling on a shelf for a few years, to borrow a term from brewing literature. Extensive time under acidic conditions may help release bound damascenone just like acid catalyzed time under heat. Staling may be a secret of vinegar process grand arôme rums that employ very long fermentation times under very acidic conditions (pH 3.0). This raspberry liqueur was as stale as they come, but with no negative attributes of aging besides a minor darkening of color.
If examining raspberry liqueur wasn’t already speculative, raspberry ketone is also a wild card. What is it, where is it, and what does it feel like?
To cut to the chase, I certainly found no meaningful amount of Damascenone, but I think I found raspberry ketone in fraction 5. This simple exercise was not too insightful on the surface, but it will lay a foundation for understanding that even though damascenone is reported to be everywhere, it may not be in meaningful amounts. Through performing the experiment I also learned how I lost a few ml of absolute alcohol (I noticed in fraction 4) which I will have to correct next time I do something similar.
I did my tasting using only a percentage of each 25 ml fraction and re-combined the rest into a quick eau-de-vie estimated at just about 40% to see what it would feel like. It was quite light and not very remarkable. It certainly had raspberry identity, but a hollowness. What this makes me wonder is that for a raspberry eau-de-vie does it have to be ameliorated during fermentation in a way that fills the space with a normal level of ethyl acetate, fusel oil, and esters. What I think was raspberry ketone was providing a focused persistence, but it was not enough to power the whole experience. Something was missing that is needed to fill the voids.
These voids are an interesting thing. The raspberry liqueur fills them in with non-volatile features like sugar and acidity while an eau-de-vie would have to fill them in with volatile features like esters, fusel oil, and noble volatile acids.
An amount of liqueur was scaled to 100 ml of absolute alcohol and stripped in the birectifier using a 3000 ml boiling flask. 250 ml were collected. Next this was re-fractioned with the traditional birectifier method collecting only the first 6 fractions. (It may be wise in the future if performing a stripping run to start with 105 ml or more if you have the resources to accurately measure the ABV after the stripping run.)
Fraction 1: Initially before diluting there was a green quality found reminiscent of raspberry leaves. It has a vegetal quality. This fraction has non-culinary aromas associated with ethyl acetate and acetaldehyde. There aren’t much other unique details. This product has a grape spirit as fortifier, but also a raspberry wine quotient. It is hard to speculate where most of the headiness comes from.
If you make a similarly structured product, there may be great lessons learned by comparing your product to Port Wine or another role model. If you were light on ethyl acetate and other heady features you may want to use a fuller bodied fortifier if that was an option.
Fraction 2: Not too much aroma, nothing non-culinary. A little generic non-defining fruitiness.
Fraction 3: Extremely neutral. Very clean on the palate.
Fraction 4: Defining aroma starts to emerge. Possible raspberry ketone? No prominent fusel oil. This fraction was collected at less than 25 ml because the temperature started to climb and risked dumping distillate meant for fraction 5 into fraction 4. I scaled the original charge of the stripping run for 100 ml of absolute alcohol, stripped it to 250 ml (so plenty of water), and then did a traditional birectifier fractioning. Somewhere along the way a few ml’s of absolute alcohol were lost.
Fraction 5: There is a little bit of a bitter woody character. No body. It feels very thin. There is a fruitiness but it feels very different than esteriness. The aroma is quite nice but it does not have the intensity of a fraction 5 from a full flavored spirit (Remember this is just a liqueur, and a quite good one, I’m only making comparisons to other experiences).
Fraction 6: I accidentally destroyed this fraction. :(
I did not collect the last two traditional fractions because I didn’t think they could answer any questions I had.