Sweet fennel oil
Under the IFRA Standards a rinse-off soap may hold up to 0.17 % of this oil, a limit set by its Estragole.
IFRA maximum for soap
Restricted constituents, at the typical levels IFRA's annex gives:
- Estragole
- 2.32 %
- p-Methoxybenzaldehyde
- 0.47 %
Worked out from typical levels. A supplier's certificate for your lot comes first, and its figure is the one to follow.
Check a blend against its IFRA limits and list its allergens in the fragrance and allergen calculator.
How essential oils behave in soap, and how much to use: Scenting soap.
Identity and labelling
Foeniculum Vulgare Oil
- Botanical name
- Foeniculum vulgare
- CAS
- 84625-39-8, 8006-84-6
The EU does not name this oil itself as an allergen to label, but some of its constituents may be: the fragrance allergen tool works them out for a recipe.
What it is and how it behaves in soap
Sweet fennel oil is steam-distilled from the fruit, the seeds, of Foeniculum vulgare var. dulce. About four-fifths of it is trans-anethole (EFSA), and it smells of sweet aniseed with a green, herbal edge. Bitter fennel is a different oil with far more fenchone (ISO 17412), so check the label.
Faiola's 2013 book lists fennel among the essential oils that behave well in cold process, and her recipes use it at 1.2 % of the oils, or as a quarter of a lavender and patchouli blend. Those rates are far above the IFRA figure on this page, which is among the lowest here because fennel carries a few percent of estragole (EFSA). The figure is the ceiling, and it makes fennel a trace accent at most.
Oils sold as fennel have turned out to be synthetic anethole, star anise oil or solvent (Murphy and colleagues), so buy from a supplier who tests.
Sources
- CosIng, the cosmetic ingredient database: FOENICULUM VULGARE OIL, European Commission
- EFSA FEEDAP Panel, Safety and efficacy of feed additives consisting of essential oils from the fruit and stems of Foeniculum vulgare Mill. (fennel oils), EFSA Journal (2023). Steam distillation of the fruit; sweet fennel oil about 78 % trans-anethole and 4.4 % estragole
- ISO 17412:2007, oil of bitter fennel, International Organization for Standardization (2007). Bitter fennel oil has 10 to 25 % fenchone
- Anne-Marie Faiola, Soap Crafting, Storey Publishing (2013). Fennel among the essential oils that are typically wonderful in cold process soap; fennel as a quarter of a lavender and patchouli blend
- Anne-Marie Faiola, Pure Soapmaking, Storey Publishing (2016). Fennel with lavender at 1.2 % of the oils
- Murphy and colleagues, Authentication of fennel, star anise, and anise essential oils by gas chromatography (GC/MS) and stable isotope ratio (GC/IRMS) analyses, Plants 13, MDPI (2024). Three commercial fennel oils were adulterated: triethyl citrate, synthetic anethole, and star anise oil sold as fennel