0.88 oz × 29.57 ml × 0.789 g/ml = 21 g · about 144 kcal from the alcohol alone
IN THE GLASS
DIACETYL
FROM WHITE RUM CANE · the butter note
Formula
C₄H₆O₂
Mass
86.09 g/mol
IUPAC
butane-2,3-dione
The butter note. Wanted in oak-aged Chardonnay and certain ales (English bitter, Czech pilsner) where a controlled amount adds body; unwanted at high concentrations, where it slides into movie-theater-popcorn territory. Yeast produces it as an intermediate during fermentation and reabsorbs it during conditioning. A rushed beer that skipped its conditioning rest often carries diacetyl as an off-flavor the brewer didn't intend.
Lemon's defining note: technically a mix of two geometric isomers (geranial and neral) that read as the same aroma to the nose. Lemon peel, lemongrass, lemon verbena, and Indian chai all carry it. In cocktails it's what a lemon twist contributes that lemon juice can't: the volatile expressed from the oil glands, not the acid from the pulp.
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.
White rum, grapefruit, lime and maraschino, with no sugar. Citral from lime and d-limonene from grapefruit build the nose, and maraschino contributes benzaldehyde (cherry pit). Hemingway asked for his without sugar and with double the rum. The recipe here is the standard-pour variant, not the 'Papa Doble'.
PROVENANCE
Constantino Ribalaigua Vert created the original at Havana's El Floridita; Hemingway, a regular, asked for it without sugar and with double rum, the 'Papa Doble.' The standard-pour version (this one) keeps the original's touch of maraschino at a single measure of rum. The grapefruit is what distinguishes it from a regular Daiquiri: a softer, more aromatic citrus profile against the rum.
