Method:
I decided to use Havana Club Anejo Blanco (don't own Bacardi and am not going to change that) as an example for pure white rum. Seales 10 Years will have to stand fast in face of my terror as it's the only rum I'm certainly sure has no relevant additives to begin with.
The sugar syrup was produced by creating a 50/50 solution of sugar and water and heating things up. The resulting liquid was brought up to 86 proof with a rare vodka of my girlfriend’s parents (otherwise the addition of sugar would’ve meant the reduction of alcohol at the same time – which is rather problematic). The rums were poured into my tasting glasses until 4cl were reached. Then the syrup was added with a clinical injection. I used a labor scale sponsored by my girlfriend (she is biologist) to adjust the further addition of syrup after I took my sips… so from a scientific point of view we should be all clear:
Now to the Results:
Pure:
Havana Blanco: The smell speaks of a raw young rum. Nothing smooth here, very straight. Slight remembrance of pear and fresh apple. The taste mainly follows on the apple, though there are some pear notes available – resembling the nose. Furthermore it’s quite burny on the palate. Nice fresh rum but normally I would not want to sip it.
Seales 10: The smell appears classy. I notice dark dry fruits, leather, oakey notes, also sweet tendencies with a hint of caramel and molasses. Here we find a complex rummy taste arrangement that I don’t find easy to analyze. However I’m sure of leather, oak, almond, caramel and little bit of dried plums.
In sum: Two rums of good quality but both with a noticeable straightness and a little alcoholic tingle.
Let’s see what the addition of sugar does to them:
1g sugar/l:
Havana Blanco: Whoa. It. Changes. I am totally surprised (don’t doubt my sanity I used a clinical injection to be really sure of the added amount of syrup). The tastes remain similar but the burn is reduced significantly. A slight sweetness appears.
Seales 10: Here we can detect a shift in balance as well. The alcoholic burn – while still there – steps a little bit back. I am strongly reminded of Angostura 1919 (let’s see whether that trend continues).
5g sugar/l:
Havana Blanco: The smell changed to a milder, indeed more pleasant one. Taste-wise I begin to notice sweet apple and pear. Furthermore the alcoholic feel is now largely gone (we reach the point of much more refined spirits in this area).
Seales 10: The further addition of sugar brings a taste very similar to Diplomatico Reserva Exclusiva. The nuts and almond flavor is much prominent and features a cakey and interesting impression. I would stop here. For people who do like the sweeter rum, Seales 10 with 5g/l might actually be the perfect choice  . Alas science awaits…
10g sugar/l:
Havana Blanco: Now we are getting serious. The alcohol burn disappeared. I notice notes of caramel, vanilla and molasses additionally to the persisting fruity flavors. The smell stays constant in comparison to 5g/l. If a young rum with this taste profile is actually sold it will probably receive favorable reviews since it’s soooo smooooth (and not bitter, if you know what I mean
).Seales 10: Now we have totally transformed this one. The good man your father once was, is gone… The direction goes even further in a mild sweetish area but the leather, oak and plum is actually receding in favor of coffee, vanilla, caramel and molasses. We are on par with Angostura 1919 and Zacapa 23 now. Not very exciting but caressing to the palate.
15g sugar/l:
Havana Blanco: Now this I would expect a 5-6 year old spirit from cuba to taste like. We are on an equal level of smoothness with the more expensive Havana Especial. Furthermore a hazelnut note becomes notable. Definitely sippable if sweet rums are your choice. The essential difference to Seales 10 is that Havana Blanco until now mainly gained additional flavor aspects by the addition of sugar. We will see what’s happening.
Seales 10: Holy crap. This is blasphemy. Now we are really left with the oh-so-great-flavor of Zacapa, Angostura and Diplomatico. No hint of alcoholic tingle, no oak, no leather, just smooth vanilla, caramel, coffee, burned sugar… and we reached that point at 10-15 g/l, many spirits add more than double this amount. On to the semi-final…
30g sugar/l:
Havana Blanco: No spirit at all. I am stranded with a complex flavor profile and no hint of alcohol. Don’t know what to say. If you’ve got guests who really are not into spirits (despite trying great ones) and want to convert them to the rummy side of life (without telling them they are not drinking rum at all) this might do the trick. Too sweet – now the flavors gained are receding again leaving me with apple and sugar and the still growing caramel.
Seales 10: Now I am not able to tell the difference to a Diplomatico Reserva Exlcusiva. I just tried. There are differences in the finish but the whole flavor profile is very alike. The good point for Diplomatico is that this might mean that their original unsugared rum could in fact be not only decent but great without the sugar – but if they want to cater to the smoooooth-masses then… whatever. We are bordering on too sweet here as well.
40g sugar/l:
Havana Blanco: No big difference to 30g/l. Really. Perhaps we reached the point where one is simply beating a dead man…
Seales 10: No big deal either… if one wants to achieve the sugared-rum taste profile 40g/l might be the amount needed to be sure to get everything out of it. We will see whether 50g/l change anything.
50g sugar/l (god beware):
Havana Blanco: Bah. Don’t ever do this. We do have liqueur now. Reminds me of Legendario Elixir de Cuba (only with more alcohol, which I don’t notice anymore). If this would be sold as rum without flavoring even newbies to the rum business should become skeptical.
Seales 10: Oh my poor Seales. He resists the sugary revolution much more than the Havana Blanco does. Staying quite complex, holding on to some not-so-sweet flavor aspects. Nevertheless we reached the point of liqueur here too.
Conclusion:
Surprisingly (for me): 1g/l actually changes things. That’s important. The addition of sugar to rums (that are good to begin with) brings exactly the smoothness, the buttercookie flavor, the caramel, the vanilla, you name it, that many reviewers regard so highly and desirable. Three decisive steps were identified on the way to liqueur.
The first one is 1g/l. The decision to actually add sugar – albeit very small amounts – softens the edges and makes a spirit more open for anyone not into the more piratey feelings… Then we reach 10-15g/l. Here we can make Havana Blanco as smooth as a 5 year-old spirit without sugar. Hence we can cheat. Hence we don’t want to do that, do we?
The last barrier is 35-40g/l. This is the last step before overdoing and leaving the world of spirits by entering the realm of liqueur. At 40g/l I still believed it is rum – a very smoooooth, pansy one though. However these ‘qualities’ are valued by many reviewers and many sippers and it is no surprise that some companies take their spirits (which could be sold to more serious but less numerous consumers as well) and sweeten them up.
What to do about it:
As Jimbo pointed out, there is not much to be done. I recommend for everyone to take a rather pure rum and repeat my experiment so he can taste with his own palate what happens. Now I am really equipped to identify offenders… my first target will be Mount Gay XO because I want to be totally sure that this smoothness does not result from sugaring – but will I be able to even notice 1g/l – probably not.
As long as no strict rulings about the composition of rums are enforced we will have to believe unless we get governmental information as was the case in another interesting thread.
