BESIDES VANILLA, MOLASSES AND BAKING SPICE, WHAT OTHER RUM-ASSOCIATED FLAVOR NOTES ARE THERE TO BE INTERPRETED BY THE BRAIN? Typical for most spirits, we see all classes of chemical compounds produced — especially through fermentation which, for rums, includes the inoculation of the sugar cane juice or molasses with yeast plus or minus certain species of bacteria (see Figure 1). Volatile and flavorful classes of molecules include: esters (solventy, fruity and floral notes), higher alcohols (solventy, floral, bitter), terpenoids (think resins and hop and gin-like flavors), acetals (delicate earthy, nutty, green and ethereal), aldehydes (green, cheesy/fatty/sweaty and waxy notes), phenols (medicinal, band-aid, spicy-clove-like), ketones (e.g., diacetyl — buttery), furans and other “cooked” Maillard heterocyclic compounds (burnt, sweet-nutty, bready, meaty and roasted nuances), and organic acids (pungent, sour, dairy and cheesy). These flavor notes were detailed recently (8) and the reader is referred there and to Table 2 for more information. Key flavors are also derived from wood maturation and include vanilla, eugenol (clovespicy phenolics), and lactones (coconut, nutty, celery — the heavy fruity and fatty notes of peaches and plums are also described as “lactony”). So much for describing rums with only the terms vanilla, molasses, and baking spices. All the metabolites, raw-material extractives, and chemical reactions (leading to more volatile flavor molecules) produce a harmony which we call the rum experience. Some are very pleasant, some less so, but the marriage gives us what we have come to know and like in our favorite rums.
23 BASIC FLAVOR TERMS
DERIVED FROM A SERIES OF SENSORY EVALUATIONS DEFINING THE TOP 14 ATTRIBUTES DEEMED OF IMPORTANCE IN VARIOUS RUM STYLE OR BARREL AGE CATEGORIES. [SEE TEXT AND REF 1.]
THROUGH WHICH TO START DESCRIBING RUMS
BANANA BUTTERSCOTCH CARAMEL CHOCOLATE CINNAMON CITRUS COCONUT CREAM FLORAL
GETTING A LITTLE DEEPER
Early research (9) showed 184 volatile compounds in unaged sugar cane spirit (known as aguardiente) and in three- and seven-year old cask rums. These components included 64 esters, 47 benzenic compounds, 16 terpenoids, 14 alcohols, 10 acetals, nine aldehydes, six phenols, six ketones, six furans, three acids and three benzopyrans. Moreover, the use of only 15 volatile compounds permitted a differentiation between the three- and seven-year-old rums (9). Ethyl esters were found to be the most prevalent along with 3-methyl-1-butanol and 2-methyl-1-butanol (the key fusel alcohols or fusel oils) (3,9). The flavor descriptors are provided for these and other compounds in Table 2. As a spectrum, rums — light and heavy (aged and unaged), simply by broad strokes, may be assessed as being: pungent, solventy, spicy, grainy, malty, floral, vanilla, soapy, sour, nutty, oily, woody, sulfury, sherry-like, sweet, burnt and molasses-like (5). To which we can add fruity and buttery. More extensive terms for white, gold and aged rums are specified in a rum flavor wheel presented by the Cadwallader group (1). (As an aside, Ickes and Cadwallader also initiated the first sensory study to evaluate the effects of the ethanol concentration on the flavor perception of rum (10).) An extended list of volatiles found in rums can also be found in the thesis by Burnside (11), and the reader should also seek out the dissertation by Gomez (6) for lists of aromatic compounds present in molasses and those compounds that might be derived from wood. Obviously, depending on type and process, many of these compounds end up in your rums. Several white, gold and aged rums (2-5-year, 5-10-year, 10-20-year and 20 years +) were evaluated by Ickes, Lee and Cadwallader (1) and the top 14 flavor descriptors for each category of rum evaluated. (Note: the authors titled their table the Top 15, but only 14 terms appeared in each column. Maybe they had
HONEY MINERAL MOLASSES NUTTY OAK ORANGE SPICES SUGAR TOBACCO TOFFEE VANILLA WOODY The listing is presented alphabetically and may not represent the order with which they are detected by the senses when evaluating rums. The detection of compounds from complex matrixes is dependent upon many physical, chemical and biochemical variables beyond the scope of this review (18). See reference 1 for the details concerning this listing of components. From this we can begin to look at the chemical flavor classes that give rise to these “flavor” notes (see Table 2).
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