Rum Aging Science Vol. 3
In Volume 1 of Rum Aging Science (published from January through December of 2020), we explored the aging of rum in American Oak, ex-Whiskey barrels. In Volume 2 (published from January through December of 2021) we explored the aging of rum in new American Oak barrels. This year’s Volume explores the aging of rum in French Oak barrels.
The Rum: Just as we did in Volumes 1 and 2, this new series starts using a low-congener, column-distilled rum, made from fermented HT (High Test or “miel virgen”) molasses. We use low-congener rum so that we can focus more on detecting the wood extractables and their impact on the rum’s profile.
The Barrel: For this series we selected a barrel made by Independent Stave Company (https://www.independentstavecompany.com), with toasted staves and Char #1 heads.
The Wood Extractives: The compositions of both American Oak and French Oak have a lot of things in common: they are, after all, both oaks. But the proportions of the components that are extractable by alcohol differ between the two types of oak. These extractives include:
- Cellulose - is the most abundant natural polymer on earth. It consists of linear chains of glucose units and remains relatively intact even after wood curing and toasting.
- Hemicellulose - also known as a “wood sugar” is a two-dimensional polymer comprised of many simple sugars, including: Glucose, Xylose, Mannose, Arabinose, Galactose and Rhamnose.
- Lignin - despite the fact that it is also one of the most abundant nature-produced materials on earth, lignin remains one of the least understood. Oak ligning consists of two building blocks: guaiacyl and syringyl. The former is responsible for producing coniferaldehyde, vanillin and vanillic acid, which -especially the vanillin- are easily recognized in cask-condition spirits.
- Oak tannins - these plant polyphenols derive their name from the Latin word tannum, which means “crushed oak bark,” since in early times oak trees served as a major source of tannin for the leather-tannin industry. Tannins improve aged rum’s character by increasing the perception of balance, complexity and roundness.
Scope of Study
Each month we will evaluate a sample of the rum collected from the barrel and will report its pH, ABV and color. We’ll compare these results against those obtained from the rums in volumes 1 and 2.
Rum samples for May
Rum aged in a new, French oak barrel, after 4 months
Our rum has now spent four months inside its barrel at Rum Central’s aging cellar. April was another month of temperature extremes, with morning temperatures often in the low 40s (F) and afternoon highs in the 90s (F).
Organoleptic Changes
With each passing month, the rum’s aroma becomes more and more enjoyable. Some attractive aromatic notes have started to emerge, with fruitiness and acidity that combine very well with the French Oak wood extractives. The taste is still on the astringent side, but it will continue to mellow as the ambient oxygen reduces the tannins in the rum.
Physical Changes
These are the pH readings, as recorded on the 1st day of each month, compared to the rums from the previous Volumes, which were aged in American Oak barrels.
pH readings for May
And these are the changes in ABV % readings (as of first day of each month), also compared to the American Oak barrels:
ABV Readings for May
Join us again next month, as we continue to explore the fascinating world of rum aging!