Note: the following was transplanted from another thread in which MJL related the consensus in bourbon circles re overaging in oak. Believe me, understanding the process of distillation, aging in oak and blending will greatly improve your ability to taste and understand rum.
Know this: it won't take much for you to know more than the Preacher and his droning flock...
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Thanks for the compliments. We work very hard to make our reviews accessible and to communicate using shared (and common) life experiences. Like "Bananas Foster"! I was not aware of the bourbon consensus, thank you very much. But I'm not surprised. The brown spirits have much in common. All hope to preserve more flavor, all benefit (or not) from their time in oak.
Rum making is truly a great art.
Spectography aside, the best rums result from the skill and experience of the fermenter, distiller, cooper, ager and blender. Such individuals are more rare than most assume, notwithstanding marketing blather to the contrary.
Oaking is a key part of that process. Super premium rums are marketed as such largely based on the somewhat posit that if aging is good, lots of aging must be better. And that aging - with its concomitant loss of the angel's share, cooperage and storage costs - costs big money. So we end up with the Appleton 21's, et al.
Are they better? The purchaser who just parted with $100 to buy one will be hard pressed to say so. It takes a brave and independent individual to contradict the weight of marketing, cost and social pressure. As for me...
I think not.
Ten to twelve years is about the point where skilled oaking shows its greatest benefit. Going much beyond that entails some real risk. MJ, I agree with you that this is where the solera method and/or great blending pays dividends. The excesses of age can be reduced to interesting background tones, rather than dominant characteristics.
Single barrel, long aged rums are quite the opposite. Like some of the high dunder Jamaicans, or rums like the Pusser's, these are an acquired taste for a few, especially traditionalists. Accordingly Pusser's ends up in Pain Killers and the like.
Just a bit about oaking is relevent...
Oak is composed of cellulose, hemicellulose, lignin, tannins and lactones. Toasting or charring the barrel creates sugars and carmelization, among many other important chemical processes and effects. Let's briefly cover some of these:
1. Cellulose - affects wines, but generally not spirits.
2. Hemicellulose - source of sugars, carmelization, body and color.
3. Lignin - adds to color, complexity, vanillans and oxidation.
4. Tannins - leads to astringency, participates in oxidation and removal of "off-flavors". Tannins can provide some of the lovely aromatic high tones in rum.
5. Lactones - these are expecially evident in the bourbons and lead to its woodiness, and characteristic bourbon color and taste. Isomers of lactones have been described as woody, coconut and celery-like.
6. Charring - helps remove off-flavors (eg rubberiness) and leads to smoky tones (but a lot less than you might think).
One of the problems in oaking is that there are competing and/or simultaneous processes. While the tannins are producing their wonderful high and aromatic tones, the lactones are growing to perhaps obliterate them with overly woody characteristics. Finding a desired balance is an art.
To make matters even more complicated, Ian Wisniewski of Whisky World:
He adds:"The archetypal ‘maturation mandate’ is to reach a balance between the beneficial characteristics gained from the oak, while also retaining and developing the individual ‘distillery character’ embodied in new make spirit. Because different malts have varying ageing potential, longer maturation does not guarantee a finer malt. It’s a case of variations on a theme: yielding different expressions at different ages, as the oak influence intensifies. Moreover, the appeal of a malt may be a case of ‘less is more,’ or ‘more is more’. The ‘right age’ depends on your own palate."
I will leave it there."Maturation can be divided into three essential elements. Subtractive maturation, like a ‘rites of passage’ for the ingenu new make spirit, entails the loss of immaturity. Additive maturation sees the oak endowing the spirit with colour, aromas and flavours, while interactive maturation refers to reactions between the spirit and the oak. This is something of a ‘mystical union’ that is not fully understood, yielding an additional range of characteristics that neither the spirit or oak possess individually."