1,8-Cineole

1,8-Cineole (also called eucalyptol, referred to as cineole on this page) is a terpene measured between 15% and 44% in cardamom oil [1], [2]. Its scent is fresh and camphoric [2]. This is the characteristic scent of eucalyptus oil. It is not alone in cardamom. Sweet-smelling alpha-terpinyl acetate constitutes the other large fraction of the oil [2]. Cardamom character emerges from these two compounds. In black cardamom and eucalyptus oils, cineole is the primary single constituent [3], [4]. Food and beverage manufacturers use it as cardamom flavor, and perfume manufacturers purchase it as a fragrance ingredient [5].

Where is it in cardamom, and how much is present?

The cineole ratio is higher in the husk than in the seed. Cardamom (Elettaria cardamomum) fruit consists of a dry husk encasing the seeds. The oil is obtained by hydrodistillation or steam distillation of dried seeds. In South India, seeds and husks were distilled separately. Cineole was measured at 15.1% in seeds and 23.7% in husks. Terpinyl acetate was found at 56.9% in seeds and 51.3% in husks [1]. Distillation of dried seeds yielded 5.0% to 6.7% oil [6], [7]. Supercritical CO₂ extraction yielded 5.5% oil, and its composition was similar to that of distilled oil [6].

Cultivar inverts the ratio. Six cardamom varieties were grown at the same station in India. In two varieties, cineole was high at 40.8% and 43.9%. The authors recorded their aroma as camphoric. In two varieties, terpinyl acetate was high at 40.3% and 41.6%. Their aroma was recorded as sweet and pleasant. In two varieties, linalool reached 7.1% and 11.1% [2]. In four Indian varieties, cineole was measured between 28.9% and 34.9%, and terpinyl acetate was 26.7% in one variety [8].

Light and distillation conditions shift the ratio. When the same cultivar was grown in shade, cineole was higher. Grown in sunlight, terpinyl acetate was higher [9]. In oils obtained from the same seed lot under different distillation conditions, cineole varied between 26.6% and 39.3%, and terpinyl acetate varied between 22.9% and 40.6% [10]. If grinding generates heat, volatiles escape. Cold grinding with ice increased oil yield by 1% [11].

Leaf oil is not seed oil. In East India, cardamom leaf oil contained 20.7% cineole, 18.1% camphene, and 10.0% camphor. Stem oil contained 19.8% terpinyl acetate and 10.4% cineole [12]. In one study, leaf oil was obtained at a 0.6% yield, containing 25.2% cineole. In the same study, commercial seed oil contained 46.1% terpinyl acetate and 31.2% cineole [13].

Black cardamom is a different plant. Black cardamom (Amomum subulatum) is grown in the Sikkim region of India, and its oil is cineole-dominant. In four studies, cineole was measured between 61.3% and 86.0% [14], [15], [16], [3]. Terpinyl acetate was not detected in the oils of four varieties [15]. The ratio is determined by measurement, not the common plant name.

Cineole, terpinyl acetate, 1,4-cineole: what is the difference?

Values are taken from PubChem. XLogP shows whether a substance is closer to oil or to water. The higher the value, the more oil-loving the substance. With a value of 2.5, cineole is closer to water than limonene and pinene, yet it remains poorly soluble in water. The aqueous solubility of seven terpenes was measured, and the ranking followed the calculated partition coefficients [17]. Alpha-terpineol, at 1.8, is the compound closest to water in the table.

Cineole does not degrade easily. Terpenes such as limonene and myrcene oxidize in air. The cineole molecule lacks vulnerable sites for air oxidation. It remained chemically stable in model wine for two years [18].

Terpinyl acetate can hydrolyze, cineole cannot. Terpinyl acetate is an ester of alpha-terpineol and acetic acid. If the bond hydrolyzes, alpha-terpineol remains. Cineole does not contain such a hydrolyzable bond.

1,4-Cineole is an isomer. Both molecules share the same formula. The ether oxygen is bonded at a different ring position, giving them distinct structures [19]. Both cineoles have been detected in cardamom seed oil [20]. If a certificate lists only "cineole", the specific isomer is unspecified.

What is it used for?

Food and beverage: cardamom flavoring. Cardamom fruit is used as a spice and flavoring agent [5]. The aroma profile of cineole has been measured in wine. French red wines contained up to 2.6 micrograms per liter of cineole, imparting menthol and green notes. In some wines, this exceeded the aroma detection threshold [21]. In Australia, consumers accepted cineole in red wine up to 27.5 micrograms per liter, rejecting higher levels [22]. It has also been evaluated as a preservative. Cineole, studied as the major component of cardamom oil, inhibited Listeria, Salmonella, E. coli, and Staphylococcus aureus in meat stored refrigerated for seven days without altering meat color. The minimum inhibitory concentration in the laboratory was 12.5 to 25.0 mg/mL [23]. Cumin, savory, and cardamom oils were added to soybean oil at 0.2% to 0.6%. Levels of 0.4% and 0.6% reduced the peroxide value, while sensory flavor scores did not differ across the three concentrations [24].

Cosmetics and perfume: fragrance ingredient. Cardamom is used in the fragrance industry [5]. Cineole has a distinct effect on skin, described along with labeling in the section "How does it behave in formulations?".

Aromatherapy: inhaling it helped with nausea and attention. Among 70 mothers undergoing cesarean section, half inhaled cardamom-oil-soaked gauze at the onset of nausea. Nausea severity on a 100-point scale dropped to 13.1 in the cardamom group and 25.3 in the placebo group. The cineole content of the oil was not reported [25]. Twenty volunteers completed arithmetic and attention tests in a rosemary-scented cubicle. Higher blood cineole levels correlated with improved speed and accuracy. The only inverse finding involved mood: higher cineole correlated with decreased contentment scores [26]. Inhaled pure cineole reduced anxiety- and depression-like behaviors in mice [27].

15% or 44%: which form?

Essential oils can also be supplied diluted in edible oils. The certificate should state what the percentage refers to: the oil itself or the diluted product.

Why cardamom oil instead of an isolated molecule? For food manufacturers, the reason is the overall flavor profile. Cultivars high in cineole smelled camphoric, whereas cultivars high in terpinyl acetate smelled sweet [2]. Cardamom aroma arises from this balance. Cineole-dominant black cardamom oil has been described as having a harsh eucalyptus odor [16]. For perfume manufacturers, the difference is identical: minor components enrich the fragrance. In cardamom oil, linalool, linalyl acetate, limonene, and sabinene accompany cineole [6], [29].

The selection depends on four questions.

• Which profile is required? A camphoric profile (cineole above 40%) or a sweet profile (terpinyl acetate above 40%) [2]? Both are genuine cardamom. The certificate lines clarify the difference.
• Oil-based or aqueous product? Cineole is poorly soluble in water [17]. Aqueous products require an emulsion or a carrier. Cardamom oil has been formulated into nanoemulsions alongside ginger and cinnamon oils [31].
• How much is needed? If 4 kg of cardamom oil is added to 1 ton of cooking oil (0.4%, an effective low level in an antioxidant study [24]) and the oil contains 28.9% cineole [8], the product contains 1.2 kg of cineole. These figures are illustrative.
• Price. Because cineole has been measured between 15.1% and 43.9% in cardamom oil [1], [2], the cost per kilogram of cineole can vary nearly threefold between oils. If purchasing for cardamom character, compare pricing alongside the terpinyl acetate content.

How to read an analytical report?

Method. Cardamom oil is analyzed by gas chromatography (GC) to separate volatile components, and constituents are identified by mass spectrometry. Percentages are usually calculated by peak area normalization.

Cineole and terpinyl acetate are interpreted together. In three studies, terpinyl acetate levels exceeded cineole [1], [6], [13]. In two studies, cineole was higher [8], [28]. Higher cineole can result from a camphoric variety [2], shade cultivation [9], distillation conditions [10], or leaf material [12]. If terpinyl acetate is completely absent, the oil may be black cardamom [15]. High camphene and camphor may indicate leaf oil [12]. Linalool has been measured at 5.4% to 11.1% and linalyl acetate at 5.8% to 8.2%, and both vary by variety [2], [6], [29]. Cineole differed nearly threefold across published oils [1], [2].

A specification differs from test results. A specification represents the manufacturer commitment. The measured value is the specific result of that lot. A technical data sheet (TDS) is a general document, whereas a certificate of analysis (CoA) belongs to a specific lot.

What indicates quality?

The terpineol line. Alpha-terpineol was measured at 4.7% in seed oil and 5.3% in husk oil [1]. When terpinyl acetate hydrolyzes, alpha-terpineol forms. If this line is abnormally high, terpinyl acetate hydrolysis may have occurred.

Solvent residues and raw material testing. Steam distillation and CO₂ extraction use no organic solvents. A residual solvent line is meaningful only for solvent-extracted products. An oleoresin certificate does not carry the same lines as an oil certificate: limonene dominates in the hexane extract [6]. Pesticide and heavy metal results are also read for botanical raw materials.

How does it behave in formulations?

Heat and storage. Bay laurel oil that was half cineole was stored for one year under refrigeration, ambient temperature, and heat. The composition changed least in the refrigerator and most under heat [32]. Store in sealed, full containers in a cool, dark environment.

Packaging. Among wine closures, only synthetic corks showed significant absorption, absorbing 14% of wine cineole over one year [18]. Account for cineole loss when products contact plastics.

Water and fermentation. Cineole is poorly soluble in water [17]. It dissolves in alcohol and fixed oils. Among 104 tested yeasts, only one hydrolyzed terpinyl acetate, and twelve hydrolyzed linalyl acetate [33].

Skin: penetration enhancement. In an excised human skin sample, pure cineole increased the permeation of a test drug nearly 95-fold, whereas alpha-pinene increased it twofold. Whole essential oils were less effective than isolated terpenes [34]. This provides an advantage for transdermal delivery formulations. It must be accounted for if unwanted compounds are present. Fragrance labeling depends on product classification and regional regulations.

Cosmetics labeling: cineole and terpinyl acetate are not listed; limonene, linalool, linalyl acetate, and pinenes are listed. Cineole and alpha-terpinyl acetate are not listed as mandatory fragrance allergens in the European Union. Limonene and linalool, found naturally in cardamom oil, were already on the list. Linalyl acetate, alpha-pinene, and beta-pinene were added in 2023. Alpha-terpineol, the hydrolysis product of terpinyl acetate, was also added in 2023. Allergens must be labeled when exceeding 0.001% in leave-on products and 0.01% in rinse-off products. Compliance obligations for new products began on July 31, 2026 [35].

It passes through the body quickly. In a human subject administered 1.0 mg cineole via sage tea, blood levels of parent cineole remained low, and metabolites were excreted in urine within 10 hours. More than half of the administered dose was cleared via this pathway [36].

Safety documentation. Follow the product safety data sheet (SDS) when handling extracts. Transport and storage classifications are detailed in the SDS.