We made some rum balls yesterday, and, being out of rum, decided to go with some imitation rum flavoring to avoid having to buy a whole big flask. I looked at the package and noticed that it contained 35% alcohol. This, despite the word “imitation”, makes me wonder if in fact rum flavoring is indeed very low quality rum. Is this so?
McCormick Imitation Rum Extract contains “ALCOHOL (35%), CORN SYRUP, PROPYLENE GLYCOL, WATER, ARTIFICIAL FLAVOR, CARAMEL COLOR, AND FD&C YELLOW 5 AND RED 40.” Doesn’t sound like a “real” rum to me.
The percentage of alcohol isn’t much different from real rum (35%= 70 proof), but I bet you use a lot less of the imitation stuff than the real thing. In other words, the (imitation) flavor is stronger.
Definitely not ‘real’. The key ingredience in above list is the “artificial flavor”. All the rest is stabilizers, fillers, and color, to make it easy to handle, to create a volume that’s worth packaging, and to look like something.
The flavoring mixture itself consists mainly of strong-flavored chemicals, like this: http://www.vka.com/2526.htm
(This one contains some real extracts, but you only need to copy a few chemicals to imitate the base flavor.)
Mmmmmmh, ethyl acetate. Undiluted I use it as plastic glue. 
(I am not a food scientist), but I’m pretty sure that the imitation rum extract isn’t just poor-quality rum, at least not in the sense of being a distilled spirit made from fermented molasses or sugar cane juice (vesou). The flavor of rum comes primarily from caramelized sugars (some sucrose, along with glucose and fructose) and the various residual impurities remaining in the distilled product (salts, other polysaccharides, etc.). In the case of the extract, the manufacturer has started with a alcohol base, added corn syrup (a cheaper alternative to cane sugar) to get the level of sweetness right, water, and caramel color and artificial colorings to darken it up. At that point, you’ve got something that’s probably only drinkable if you’re a college freshman and you’ve already had a few. The artificial flavorings are what make it taste like rum, insofar as it does; flavor technologists attempt to identify the specific chemical compounds that result in the keynote tastes (aromas, actually, if you’re being precise) of various foods. The number and complexity of the chemical compounds that make up any particular flavor is astonishing; it’s also nearly impossible to believe how potent some of them are – in many cases almost unmeasurably small amounts of a flavoring agent are used for huge production batches. The flavoring companies don’t worry about getting it exactly right, because it’s nearly impossible to identify all of the components of a flavor given their number and the minute quantities involved; they’re generally content if they can identify from one to a handful of agents that make up the keynotes of the flavor.
Finally, as random suggests, the concentration of flavor is much higher in the extract than in “real” rum. Genuine rum extract is a concentration of rum with much of the water (and probably some of the alcohol, to maintain balance) removed.