Citrus

Orange, lemon, bergamot. The note most often confused with a fault, because citrus and sourness sit on the same axis.

Citrus character in chocolate is closely bound up with acidity, and the line between a bright citric lift and an unpleasant sourness is narrow. That makes it the single most useful note to learn to read: a bar described as citrusy by its maker and sour by a reader is often the same bar, tasted by two people with different tolerances.

The genuine version has aromatic complexity alongside the acidity — orange peel and bergamot rather than lemon juice. Trapped acetic acid from fast drying has the sharpness without the aromatics, and that is a fault rather than a characteristic.

Descriptors used: orange peel, lemon, bergamot, grapefruit, lime zest
Desirable?: Valued in fine dark chocolate at moderate levels. The most polarising note in the catalogue.

Where it comes from

The route by which this note arrives in the chocolate.

Created during fermentation
Inferred
Citric and other organic acids present in the pulp, plus esters produced during fermentation, together give a citrus-like brightness.
How to tell: Genuine citrus character has aromatic complexity — peel and zest rather than pure sourness — and it integrates with the chocolate rather than sitting on top of it.
Source: Wiley-Blackwell

When it is a fault

Acetic acid trapped by case hardening during fast drying reads as sharp and sour, and is frequently mistaken for citrus.

How to tell: Trapped acid is one-dimensional and sits on top of the chocolate. If the sharpness has no aromatic component and does not clear, it is a drying fault.

Recorded Source: Wiley-Blackwell

Pairing

Pairs naturally with actual citrus, because peel oils are fat-soluble and dissolve into cocoa butter.

Origins known for this

MadagascarReported often enough in this origin's material to be characteristic, though fermentation and roast decide whether it survives into a given bar. Orange, lemon, bergamot. The note most often confused with a fault, because citrus and sourness sit on the same axis.
TanzaniaReported often enough in this origin's material to be characteristic, though fermentation and roast decide whether it survives into a given bar. Orange, lemon, bergamot. The note most often confused with a fault, because citrus and sourness sit on the same axis.
PeruReported often enough in this origin's material to be characteristic, though fermentation and roast decide whether it survives into a given bar. Orange, lemon, bergamot. The note most often confused with a fault, because citrus and sourness sit on the same axis.

Developed during

DryingThis stage is where the note is created, amplified or destroyed. Orange, lemon, bergamot. The note most often confused with a fault, because citrus and sourness sit on the same axis.
Artificial dryingThis stage is where the note is created, amplified or destroyed. Orange, lemon, bergamot. The note most often confused with a fault, because citrus and sourness sit on the same axis.

Sources

ChocolateHQ editorial synthesis — ChocolateHQ(citation identity confirmed; passage not re-read)
Chocolate Science and Technology — Wiley-Blackwell(citation identity confirmed; passage not re-read)