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Plants · Spices

Curcuma longa L. (turmeric): rhizome oil, ISO

Curcuma longa L.

Family
Zingiberaceae

Species

BinomialCurcuma longa
Accepted nameCurcuma longa L.
WCVP statusaccepted
FamilyZingiberaceae
IPNI identifierurn:lsid:ipni.org:names:796451-1

Source: Govaerts R. (ed.), World Checklist of Vascular Plants (WCVP), Royal Botanic Gardens, Kew, accessed on 21/09/2026.

Source: Plants of the World Online (POWO), Royal Botanic Gardens, Kew, taxon page « Curcuma longa L. », archived copy of 23/10/2026 (Internet Archive), accessed on 29/10/2026.

According to the World Checklist of Vascular Plants (WCVP, Kew), in the extract read on 21 September 2026, Curcuma longa L. is a name of rank “Species” with the status “Accepted”, placed in the family Zingiberaceae.

This page rests on two studies of the oil distilled from the rhizome of Curcuma longa L.: Oyemitan et al. (2017), on fresh rhizomes collected at Ondo, Nigeria, and Shahimoridi et al. (2025), on rhizomes from plants grown hydroponically in Tehran, Iran, dried and ground before distillation. It also lists two ISO standards, ISO 5562 and ISO 5566, which are standards of the spice, not of the oil.

Which name is accepted, and what does WCVP record?

The WCVP record of Curcuma longa L. carries the identifier 235249.

According to the Plants of the World Online (POWO, Kew) entry for the taxon “Curcuma longa L.”, the native range of the species is given “as a cultigen from SW. India”. The same entry describes Curcuma longa as “a rhizomatous geophyte” that grows “primarily in the seasonally dry tropical biome”.

Where does the distilled plant material come from?

According to Oyemitan et al. (2017), fresh rhizomes of Curcuma longa L. were collected at Ondo (Nigeria), then identified and authenticated by a taxonomist of the Herbarium Unit of Obafemi Awolowo University (OAU), under specimen number Ife-16593. According to Shahimoridi et al. (2025), plants of Curcuma longa L. were cultivated hydroponically in the Spice Research Greenhouse of Tarbiat Modares University, Tehran (Iran). In Shahimoridi et al. (2025), healthy, uniformly sized and mature fresh rhizomes were collected at physiological maturity, 9 months after planting.

How is the plant material prepared?

According to Shahimoridi et al. (2025), before the drying experiments the cleaned rhizomes were sliced into uniform cylindrical sections 3 mm thick. In Shahimoridi et al. (2025), the slices were divided into three groups of 200 g each, moisture loss was followed by weighing at various intervals during drying until the moisture content fell below 10 %, and each drying method was repeated three times. For sun drying (SD), Shahimoridi et al. (2025) placed the slices on a linen cloth in a steel tray exposed to sunlight, at a temperature of (30–35) ± 2 °C and a relative humidity of 30 ± 5 %. For COD, Shahimoridi et al. (2025) dried the samples in a convection oven at a constant temperature of 50 °C. For vacuum oven drying (VOD), Shahimoridi et al. (2025) spread the slices on stainless steel trays and dried them in a vacuum oven at a fixed vacuum of 30 mbar and a temperature of 50 °C.

For microwave drying (MD), Shahimoridi et al. (2025) applied the treatment in a microwave oven set to a power of 500 W, weighing the samples every 5 min. For freeze drying (FD), Shahimoridi et al. (2025) froze the rhizome slices at −80 °C for 24 h, then freeze-dried them with a condenser temperature of −58 °C and a pressure of 0.1 mbar. According to Shahimoridi et al. (2025), the dried samples were ground to powder in an electric grinder, sieved through a 25-mesh sieve, then stored at −20 °C before the measurements.

How is the oil obtained?

According to the title of Oyemitan et al. (2017), the oil studied is the essential oil of the fresh rhizome of Curcuma longa (“turmeric”) cultivated in southwest Nigeria. According to Oyemitan et al. (2017), 1.5 kg of fresh rhizomes were hydrodistilled for 4 h in a Clevenger-type apparatus. In Oyemitan et al. (2017), this hydrodistillation of 1.5 kg of fresh rhizomes gave 10.5 g of essential oil, a yield written as “0.7% w/w”. According to Oyemitan et al. (2017), the oil was dried over “Mg2SO4” (written thus) and kept in a refrigerator until use. According to Shahimoridi et al. (2025), the essential oil was extracted by hydrodistillation in a Clevenger-type apparatus: 30 g of dried, ground sample, in a 1000 mL flask with 600 mL of water, were boiled for 5 h. In Shahimoridi et al. (2025), the oil yield is given in mL per 100 g of dry matter, the volume of oil being measured and its content expressed as a percentage (%V/W). According to Shahimoridi et al. (2025), the extracted oil was kept in an amber glass bottle at 4 °C until analysis, and each distillation was carried out in triplicate. In the trial of Shahimoridi et al. (2025), the highest essential oil yield, 4 % (v/w), was obtained with the FD method. In the same trial of Shahimoridi et al. (2025), the MD method came after FD, with an essential oil yield of 3.3 %. In the same trial of Shahimoridi et al. (2025), the IRD method came after FD and MD, with an essential oil yield of 2.7 % (v/w). In the paragraph of Shahimoridi et al. (2025) on essential oil yield, no significant difference was observed between the SD, COD and VOD drying methods.

What does the oil look like?

According to Oyemitan et al. (2017), the oil they obtained from fresh rhizomes (EOCL) was brownish in colour, with a characteristic pungent smell. According to Oyemitan et al. (2017), the relative density of that oil was estimated at 960 mg/mL (unit as written).

How was the oil analysed?

According to Oyemitan et al. (2017), their oil (EOCL), at 0.5 mg/mL in CH2Cl2, was analysed by GC–MS on a Focus-ISQ instrument (Thermo Scientific). In Oyemitan et al. (2017), separation was achieved on a ZB–5 ms capillary column (30 m × 0.25 mm, Phenomenex), with a temperature programme of 40 °C (2 min) ramped to 250 °C (10 m) at 5 °C/min, “(10 m)” being written thus. According to Oyemitan et al. (2017), the eluted compounds were identified by their Kovats indices, by spectral matching with the 2008 NIST spectral library, and with a known standard and the literature. According to Shahimoridi et al. (2025), GC analysis was performed on an Agilent Technologies 7890B system equipped with a flame ionisation detector (FID) and an HP-5 capillary column (30 m × 0.32 mm i.d. × 0.25 μm film thickness). In the GC-FID of Shahimoridi et al. (2025), the carrier gas was high-purity helium at 1.1 mL/min (split 1:100), the oven was programmed from 60 °C (2 min) to 280 °C at 5 °C/min with a final hold of 0 min, and the injector and detector were held at 250 °C and 280 °C. According to Shahimoridi et al. (2025), GC–MS analysis was carried out on an Agilent Technologies 7890 A system coupled with a mass spectrometer, with an HP-5 column (30 m × 0.25 mm × 0.25 μm film thickness), a programme from 60 to 250 °C at 5 °C/min, a transfer line at 250 °C, an ionisation energy of 70 eV and helium as carrier gas at 1.1 mL/min (split 1:100). According to Shahimoridi et al. (2025), the constituents of the oils were identified by comparing their mass spectra with the Wiley 7.0 and Adams libraries, and confirmed by retention indices (RIs) matched with authentic compounds, calculated using n-alkanes (C8–C24).

What is the composition of the oil?

According to Oyemitan et al. (2017), twenty-three compounds were detected in the gas chromatogram of their fresh-rhizome oil (EOCL), of which 21 were fully characterised.

Table 1 of Oyemitan et al. (2017), for the fresh-rhizome oil analysed, gives each compound with its molecular weight (MW), its Kovats index (KI) and its content in “% Area”, names as the table writes them:

  • α-pinene (MW 136, KI 933): 0.6 % Area
  • Sabinene (MW 136, KI 975): 0.2 % Area
  • Myrcene (MW 136, KI 992): 0.4 % Area
  • α-phellandrene (MW 136, KI 1004): 15.5 % Area
  • δ-3-carene (MW 136, KI 1010): 0.3 % Area
  • α-terpinene (MW 136, KI 1016): 0.5 % Area
  • p-cymene (MW 134, KI 1024): 2.1 % Area
  • D-limonene (MW 136, KI 1028): 1.0 % Area
  • 1,8-cineole (MW 154, KI 1031): 10.3 % Area
  • γ-terpinene (MW 136, KI 1060): 0.7 % Area
  • Terpinolene (MW 136, KI 1089): 3.2 % Area
  • terpinen-4-ol (MW 154, KI 1179): 0.2 % Area
  • α-terpineol (MW 154, KI 1192): 0.4 % Area
  • β-caryophyllene (MW 204, KI 1425): 0.2 % Area
  • compound noted “Unknown” (MW “–”, KI 1450): 0.3 % Area
  • ar-curcumene (MW 204, KI 1487): 0.7 % Area
  • α-zingiberene (MW 204, KI 1498): 2.0 % Area
  • β-curcumene (MW 204, KI 1512): 0.2 % Area
  • β-sesquiphellandrene (MW 204, KI 1528): 1.8 % Area
  • compound noted “Unknown” (MW “–”, KI 1608): 0.6 % Area
  • ar-turmerone (MW 216, KI 1670): 10.0 % Area
  • Turmerone (MW 218, KI 1674): 35.9 % Area
  • Curlone (MW 218, KI 1697): 12.9 % Area

According to Shahimoridi et al. (2025), a total of 53 components were identified by GC–MS in the oils of their six drying methods taken together, components the authors describe as terpenoids in terms of chemical structure. According to Shahimoridi et al. (2025), Table 3 presents the composition of the essential oils from the six drying methods; its caption gives the unit as “mg/g raw material”, the header of its six columns as “Peak Area %”.

What acute toxicity was measured in mice?

According to Oyemitan et al. (2017), the LD50 value estimated in mice for the fresh rhizome essential oil of Curcuma longa L. was 693 mg/kg by the intraperitoneal route (i.p.).

Which ISO standards does the ISO catalogue list under ICS class 67.220.10?

According to the ISO catalogue for ICS class 67.220.10, the standard ISO 5562:1983 is titled “Turmeric, whole or ground (powdered) — Specification”, falls under ISO/TC 34/SC 7 and is at stage “90.92”. In the same catalogue, the standard ISO 5566:1982 is titled “Turmeric — Determination of colouring power — Spectrophotometric method”, falls under ISO/TC 34/SC 7 and is at stage “90.93”.

References

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