Sotolone

In short

Sotolone is a furanone lactone responsible for the smell of fenugreek, lovage and maple syrup. It is one of the most powerful odorants known and is used in minute traces.

What Sotolone smells like

Sotolone is an extremely powerful lactone whose odour depends on concentration: maple syrup, caramel or burnt sugar at low levels, and fenugreek or curry at high ones. It is the character odorant of fenugreek and occurs in aged wines such as Port and vin jaune. Reported thresholds vary by medium and method; its (S)-enantiomer is the more potent.

Leading note: Maple, or fenugreek
Clear facets: Caramel, burnt sugar, curry
Character: Potent, warm, savoury-sweet

What makes Sotolone distinctive

One molecule, two smells: maple syrup in a trace, curry and fenugreek above it.

Concentration and dilution

Maple, caramel and burnt sugar at low concentration; fenugreek and curry at high concentration. Used at extreme dilution.

How Sotolone is used

Used in traces for maple, caramel and immortelle-like effects in gourmand and tobacco compositions, and in flavours.

Typical role: modifier (used in small amounts to change the character of a blend).

How Sotolone differs from similar materials

Fenugreek Absolute: Fenugreek absolute owes its maple-curry character to sotolone, and adds celery, nutty, hay and anisic notes. (compared directly by a cited source)
Cyclotene: Cyclotene is a steadier maple-caramel with walnut; sotolone turns to curry as it strengthens.

An asterisk marks a difference that a cited source states directly. The others compare the published descriptions of each material. Smell varies with grade, supplier and dilution; compare them side by side on blotters before substituting one for another.

Formulation considerations

Extremely potent; work from 0.01% or weaker. It lingers on equipment and clothing.

Identity and classification

Type: Aroma chemical
Origin: Occurs in nature
Odour family: Gourmand / Spicy
Note position: Heart to base note
Physical form at room temperature: Liquid. A clear yellow liquid as JECFA describes it, with a melting point of 25–29 °C, so it can solidify when cool.
Also known as: Sotolon, 3-Hydroxy-4,5-dimethylfuran-2(5H)-one
CAS number: 28664-35-9
Molecular formula: C6H8O3
Molecular weight: 128.13 g/mol
IUPAC name: 4-hydroxy-2,3-dimethyl-2H-furan-5-one

The CAS number, formula and molecular weight are taken from PubChem compound 62835, whose own record lists this CAS number; checked 19 October 2026.

Safety and compliance

Hazard classification of the neat substance, as PubChem summarises it, read 26 October 2026. Companies notifying the ECHA C&L Inventory classify it (1,484 reports): H302 harmful if swallowed (86.9% of reports). 194 of the reports find it does not meet the hazard criteria. Unless it is harmonised, this is the notifiers' own classification, not a binding one.

This page is general information, not a safety assessment or a specification. Confirm identity, composition, IFRA status and allergen content from your supplier's documents for the lot you hold.

Materials it works with

Fenugreek Absolute
Absolute · Gourmand / Spicy — maple, curry, celery, hay
Furaneol
Aroma chemical · Gourmand / Fruity — strawberry, caramel, jammy, sweet
Maltol
Aroma chemical · Gourmand / Fruity — caramel, sweet, bready, cooked fruit
Helichrysum Oil
Essential oil · Aromatic / Gourmand — honey, hay, curry, fruity

Sotolone is also suggested as a partner on the pages for 5-Hydroxymethylfurfural and Lovage Root Oil.

Used in formulas and accords

Used in 6 published formulas

Sotolone is an ingredient in 3 perfume formulas and 3 accords in the Formula & Accord Library.

Community formulas

Horchata Accord
Community Formula · Accord · listed as “Sugar Lactone 0.03%”, at 0.03%
Roasted Chestnut Accord
Community Formula · Accord · listed as “Sotolone (28664-35-9)”
Soy Sauce Accord
Community Formula · Accord · listed as “Caramel Furanone 0.1%”, at 0.1%

RUŌOD House Originals

Original compositions by RUŌOD House.

Dark Rum Cabinet
RUŌOD House Original · listed as “Sotolone 0.1% DPG”, at 0.1% in DPG
Maple Fog
RUŌOD House Original · listed as “Sotolone 0.1% DPG”, at 0.1% in DPG
Praline Smoke
RUŌOD House Original · listed as “Sotolone 0.1% DPG”, at 0.1% in DPG

Questions about Sotolone

Is Sotolone natural or synthetic?

The molecule occurs in nature. Commercial Sotolone may be made by synthesis or obtained from natural sources, so check the supplier's specification if the distinction matters to you.

What is the CAS number of Sotolone?

28664-35-9. It was checked against PubChem on 19 October 2026.

Which published formulas use Sotolone?

Sotolone is used in 6 published formulas in the RUŌOD Lab Formula & Accord Library, including Dark Rum Cabinet, Horchata Accord and Maple Fog. Each is listed with a link under "Used in formulas and accords" on this page.

Sources

PubChem — compound 62835, checked 19 October 2026.
PubChem — GHS classification (the ECHA C&L Inventory notifications and any harmonised EU entry), read 26 October 2026.
Wikipedia — Sotolon — published perfumery reference.
Wine with Seth — Sotolon — published perfumery reference.
Premiere Peau — Fenugreek — published perfumery reference.
Olfactory profile: the RUŌOD Lab team's synthesis of the published descriptions above, reviewed 20 October 2026. Evidence: several independent published descriptions, which agree. Classification and the short description: revision 1. Descriptions of odour are judgement, not measurement.