03GARNISH WITH A BACKSCRATCHER (TRADITIONAL) + ORCHID
1 oz taken as 30 ml in the metric column.
STRENGTH // WORKED
Pre-batch
3.06 oz mixed with ice, 1.03 oz of it pure alcohol
Melt
Shaken: +20 % of the pre-batch, +0.61 oz of water
Served
3.06 + 0.61 = 3.67 oz in the glass
Strength
1.03 ÷ 3.67 = 28.0 % ABV as served
Ethanol
1.03 oz × 29.57 ml × 0.789 g/ml = 24 g · about 168 kcal from the alcohol alone
IN THE GLASS
VANILLIN
FROM BOURBON + AGED RUM · from oak barrel aging
Formula
C₈H₈O₃
Mass
152.15 g/mol
IUPAC
4-hydroxy-3-methoxybenzaldehyde
Bourbon's fingerprint, extracted from the charred American oak the law requires for aging. Same molecule as the vanilla bean's signature, so a well-aged bourbon legitimately tastes like vanilla. Chemistry, not metaphor. Cognac, aged rum, tequila reposado all extract vanillin from oak too. Different barrels, same molecule.
The grape-candy / Welch's-grape-juice aroma. Concord grapes carry it in concentrations no European wine grape (Vitis vinifera) approaches; American Vitis labrusca grapes, native to the northeastern US, hold methyl anthranilate as a signature. The "foxy" note in North American grape juice and artificial grape candy both come from the same molecule. Also used as the standard bird repellent on commercial fruit crops; birds find it intolerable.
An orange rind, squeezed, throws a spray that catches the light. That's d-limonene boiling off. It's roughly 95% of orange peel oil by mass, and the molecule that puts the "orange" in orange anything. Used industrially as a green solvent because the chemistry that dissolves citrus oils also dissolves greasy machinery. The expressed-peel garnish on a cocktail is delivering vaporized limonene to the rim of the glass.
Bourbon, aged rum, curaçao, passion fruit and Angostura: an unusual bourbon-in-tiki pour. Tropical thiols from passion fruit lift the oak profile of both spirits. The backscratcher garnish is a literal prop: Harry Yee's joke on the drink's name.
PROVENANCE
Harry Yee created the Tropical Itch at the Hawaiian Village Hotel (now the Hilton Hawaiian Village) in 1957. Yee is also credited with the paper-umbrella garnish, and the orchid; the backscratcher in the Tropical Itch is another of his props. Yee remained at the Hawaiian Village for more than thirty years, creating most of the hotel's signature drinks. The bourbon-rum-tropical combination is unusual; most tiki uses two rums, not one rum and one whiskey.
