Basil

Basil oil comes in two quite different forms, depending on where the plant was grown. European basil runs on linalool, soft and sweet, and makes up around three fifths of the oil. Tropical basil runs on estragole instead, sharper and more aniseed-like. The linalool form held back Salmonella and Gram-positive bacteria, both in the dish and in food.^[1] In mice, basil oil and estragole together brought down swelling and the markers that go with it.^[2]

Holy Basil

Ocimum tenuiflorum

Also Known As: Tulsi, Sacred Basil, Holy Basil
Family: Herbal
Perfumery Note: Middle
Intensity: Medium
Extraction: Steam Distillation
Plant Parts: Leaves, Flowering tops
Origins: India, Southeast Asia
Effect: Focus & Mental Clarity
Aroma: Herbal, Spicy, Clove-like, Sweet
Applications: Diffusing & Inhalation
Price: $$$$Ocimum tenuiflorum (Tulsi) is cultivated mainly in India for religious and Ayurvedic markets; moderate production scale but niche demand in the aromatherapy world keeps pricing in the moderate range

Holy basil, or tulsi, is the sacred one, grown in courtyards across India and used daily in Ayurveda. It smells of cloves rather than basil, because eugenol leads instead of linalool. That is the same compound that makes clove oil numbing. The oil killed mosquito larvae at low concentrations and strongly slowed acetylcholinesterase, an enzyme insects depend on.^[3] Its practical use is as a natural pesticide as much as an aromatic.

Lemon Basil

Ocimum x citriodorum

Also Known As: Citriodorum Basil, Thai Lemon Basil
Family: Herbal
Perfumery Note: Top
Intensity: Medium
Extraction: Steam Distillation
Plant Parts: Leaves, Flowering tops
Origins: Thailand, Africa, India
Effect: Energy & Uplifting, Focus & Mental Clarity
Aroma: Citrus, Herbal, Fresh, Lemon
Applications: Diffusing & Inhalation, Cooking & Flavouring
Price: $$$$Steam distillation of Ocimum citriodorum yields only ~0.07% oil - roughly 1,400 kg of plant per kg of oil - making it significantly lower-yielding than common sweet basil

Lemon basil is a cross between sweet basil and another Ocimum, bred for the citrus. Citral does most of that, with linalool and nerol softening it into something more floral than lemongrass. It works where you want basil's herbal edge without the aniseed. The published research used extracts of the plant rather than the distilled oil, and found they protected cells and held back bacteria.^[4] Those are claims about the extract, not about what is in an oil bottle.

Sweet Basil

Ocimum basilicum

Also Known As: Common Basil, Garden Basil, European Basil
Family: Herbal
Perfumery Note: Top
Intensity: Medium
Extraction: Steam Distillation
Plant Parts: Leaves, Flowering tops
Origins: India, France, United States, Egypt
Effect: Focus & Mental Clarity
Aroma: Herbal, Sweet, Anisic, Fresh
Applications: Diffusing & Inhalation, Cooking & Flavouring
Price: $$$$Ocimum basilicum is widely cultivated across Europe and Asia for both culinary and aromatic use; the broad agricultural base and good oil yield from flowering tops keep it modestly priced

Sweet basil is the culinary one, and the oil smells like the leaf with the green turned up. Linalool gives the sweetness, estragole the aniseed edge, and the balance shifts with the season and the variety.^[5] That means two bottles of sweet basil oil can smell noticeably different.^[5] In lab tests it held back Staphylococcus aureus, E. coli and several fungi, and mopped up the unstable molecules that damage cells.^[5] Separated fractions of the oil also damped down the signals the body uses to drive inflammation.^[6]

Essential Nose

Basil

Holy Basil

Lemon Basil

Sweet Basil

References