Luis Ayala
In last month’s article, I explained how most of the rums are flavored, either through the addition of fruit extracts, spices, caramels or by aging them inside wooden barrels (which allows them to extract flavors from the barrel staves). I then explained how time and chemistry also flavor rums during aging, by affecting oxidation, acidification and esterification.
I also made the comment that most flavored/spiced rums are produced using very neutral (low congener) rum. During the weeks following the publication of the article, I received several emails from readers, asking why distillers would want to produce neutral or highly-neutral alcohol only to manually flavor it afterward, when removing all the congeners (“flavors”) formed during fermentation is an expensive process (it requires a longer distillation path, along with more steam/energy) and the resulting product is, according to the readers asking the questions, “inferior”.
The answer is simple, yet complex at the same time: congener diversity versus congener concentration. Let me elaborate: the distilleries that produce highly-rectified alcohol, use continuous distillation columns (usually a minimum of 4 columns but often times more), to produce large volumes of alcohol that can be sold to pharmaceutical, perfume, industrial and beverage clients. The distilleries’ focus is on yield and efficiency, meaning that they prioritize high alcohol production during fermentation, in the least amount of time possible, so that fermentation does not hold back the distillation process.
Focusing on high yields means selecting yeast strains that are able to produce mostly ethanol and giving the yeast all the nutritional and environmental requirements to support their sugar metabolism.
As a result of this, the congeners formed are typically (by volume) fusel oils and not aromatic fatty esters, which pot still enthusiasts usually seek when asking for “high congener” rum. The more fusel oils we want to remove from the alcohol, the more distillation columns it takes.It is possible to take the alcohol out of the first column, and Cachaça, Agricole Blanc and many Aguardientes are typically made this way, but the congener concentration often renders them “too flavorful” to be used as bases for products where other flavor combinations are desired.
Cheers!
Luis Ayala,
Editor and Publisher
http://www.linkedin.com/in/rumconsultant