KAFFIR LIME Citrus hystrix

According to the World Checklist of Vascular Plants (WCVP, Kew), in the extract read on 21/09/2026, Citrus hystrix DC. is a name of rank “Species” with status “Accepted”, placed in the family Rutaceae (identifier 2724129).

The sections below take the stored studies one product at a time.

Where were the kaffir lime leaves studied by Efendi et al. (2021) collected?

According to Efendi et al. (2021), the leaves of Citrus hystrix DC (the authors’ spelling) that they studied were collected at four locations: Ngunut, Tulungagung (8°6′27″ S, 112°0′35″ E, 109 m asl); Pasirkuda, Bogor (6°36′36″ S, 106°46′47″ E, 239 m asl); Jatiarjo, Pasuruan (7°45′5″ S, 112°40′6″ E, 803 m asl); Cikole, West Bandung (6°48′12″ S, 107°39′16″ E, 1189 m asl).

On the basis of altitude, the authors classed Bogor and Tulungagung as lowland and Pasuruan and West Bandung as highland.

The authors give, for each location, the average, minimum and maximum temperatures and the monthly and annual rainfall: Tulungagung 25.3, 20.1 and 30.1 °C, 145 and 1743 mm; Bogor 25.4, 20.1 and 30.1 °C, 342 and 4104 mm; Pasuruan 22.1, 17.4 and 26.9 °C, 261 and 3126 mm; West Bandung 20.3, 15 and 24.1 °C, 250 and 3001 mm.

When and from which trees were the leaves harvested?

According to Efendi et al. (2021), the experiment ran from February to April 2019, and the leaves were harvested at the four locations in Java in March, during the rainy season.

On each tree, the oldest fully developed leaves harvested were about 1 year old and the youngest about 1 month old.

The leaves came from 1.5-year-old trees in a monoculture garden of the local community (Tulungagung), from 2-year-old trees intercropped with leafy vegetables (West Bandung), from 2.5-year-old trees in residents’ backyards (Pasuruan), and from 1.5-year-old trees in monoculture at the IPB experimental station of Pasir Kuda (Bogor).

About 3 kg of leaves were harvested at each location, packed at once in a closed container with a cooling gel and sent to the laboratory the same day; the samples were withered for two days before distillation.

How was the kaffir lime leaves essential oil obtained and analysed by Efendi et al. (2021)?

According to Efendi et al. (2021), each kilogram of leaves underwent water-steam distillation in a stainless steel kettle for about 3 h; the oil was dried over anhydrous sodium sulfate, its volume measured, and it was stored in dark glass bottles, distillation and quality analysis taking place at the Indonesian Spice and Aromatic Plant Research Institute (Balitro).

The variables observed on the oil were yield, citronellal content and the relative content of citronellol, linalool and caryophyllene.

The authors determined these contents by GC-MS (Agilent 7890 coupled to a 5975) at the DKI Jakarta Provincial Health Laboratory, with a 1 µL injection in split mode (10:1) on a 30 m × 250 μm × 0.25 μm column that the source writes “Agilent 19091N-133HP-INNOWax Polyethylene Glyco”.

Helium flowed at constant rate, the oven was programmed from 60 °C to 210 °C (2 °C/min to 150 °C, held 1 min, then 20 °C/min to 210 °C, held 10 min), and the injector was at 230 °C.

The absolute citronellal content was estimated from a regression line built on 10 concentrations of a citronellal standard (1 to 10 %), the 1 % standard solution being prepared from about 10 μL of citronellal standard solution and 990 μL of ethyl acetate; the oils were diluted 10 times (100 μL in 900 μL of ethyl acetate), with three replications per location, and the citronellal peak area was entered into the equation (R2 0.9975).

The relative content of citronellol, linalool and caryophyllene was determined from the peak area of these compounds expressed as a percentage of the total area.

What yield and composition did Efendi et al. (2021) report for the leaf oil?

According to the abstract of Efendi et al. (2021), the highest kaffir lime leaves essential oil yield was obtained in Bogor (1.5 %), and that of Tulungagung was 0.78 %; the abstract does not state the basis of this percentage.

The absolute citronellal content of the leaf oil was significantly affected by location; for the “citronellal yield”, the authors give the decreasing order Pasuruan > Bogor = Tulungagung > West Bandung.

Location significantly affected the relative citronellol content of the leaf oil, which ranged from 2.42 % to 6.55 % across the four locations, highest in Tulungagung and lowest in Pasuruan.

The linalool content of the leaf oil was about 2.8–4.5 %, the lowest relative percentage coming from Pasuruan and the highest from West Bandung.

The relative percentages of caryophyllene in the leaf oil ranged from 0 to 2.55 %.

Which site factors did Efendi et al. (2021) correlate with the leaf oil?

According to Table 9 of Efendi et al. (2021), across four locations, the Pearson correlation coefficient between oil yield and annual rainfall (AR) is 0.83 , and with monthly rainfall (MR) 0.83 ** (: significantly correlated at the 99 % confidence level).

In the same table, the coefficient between the relative levels of citronellol (Clol) and annual rainfall (AR) is −0.85 **.

The coefficient between altitude (Al) and the relative levels of caryophyllene (Car) is −0.83 ** (Table 9), and the authors write that increased altitude was “likely associated” with a decrease in the relative levels of caryophyllene.

According to Table 10, oil yield is correlated with soil organic carbon (C-org, 0.77 **) and soil pH KCl (0.78 **), and citronellal content (Clal) with soil pH H2O (0.81 ), across four locations (: significant at the 99 % confidence level).

According to Table 11, oil yield is correlated with the plant contents of N (0.93 **), P (0.86 **) and Mg (0.92 **), across four locations.

In the same table, citronellal content (Clal) is correlated positively with leaf Ca content (0.83 **) and negatively with leaf Fe (−0.80 **), Mn (−0.87 **), Cu (−0.89 **) and Zn (−0.88 **), across four locations; the authors write that the mechanism is “still unclear”.

Where did the pericarp studied by Vihanova et al. (2023) come from?

According to Vihanova et al. (2023), the C. hystrix fruits studied were bought in local markets in Cambodia; they were peeled and the pericarp was used for the analyses.

The dried material was homogenised with a Grindomix mill; the residual moisture of the samples, determined gravimetrically at 130 °C for 1 h in triplicate, averaged 22.51 % for C. hystrix.

How were the pericarp essential oil and the supercritical CO2 extract obtained?

According to Vihanova et al. (2023), the essential oils were obtained by hydrodistillation of 100 g of ground plant material in one litre of distilled water for 3 h, in a Clevenger-type apparatus, at a distillation rate of 2–3 mL of liquid/min, then stored in 2 mL sealed glass vials at 4 °C.

The supercritical CO2 extraction was run on 10 g of ground material placed in a 100 mL stainless steel extraction vessel between two layers of glass wool, at an isocratic pressure of 200 Ba, 40 °C and a flow rate of 5 LPM, until no more extract was obtained (visual check), total time ranging from 5 to 12 min; the extracts were stored in 2 mL sealed glass vials at 4 °C.

How did Vihanova et al. (2023) analyse the oil and the extract?

The analysis was carried out on an Agilent GC-7890B with an Agilent 7693 autosampler, two columns, a fused-silica HP-5MS (30 m × 0.25 mm, 0.25 μm film) and a DB-HeavyWAX (30 m × 0.25 mm, 0.25 μm film), and a flame ionisation detector (FID) coupled to a single quadrupole mass detector (Agilent MSD-5977B).

The carrier gas was helium at 1 mL/min and the injector was at 250 °C for both columns; after 3 min the oven rose from 50 to 280 °C (3 °C/min to 120 °C, then 5 °C/min to 250 °C, a 5 min hold, then 15 °C/min to 280 °C), followed by a 20 min isothermal period; the mass detector was set at 70 eV, ion source at 230 °C, 1 s scan, mass range 40–600.

Compounds were identified by comparing retention indices (RI), retention times and mass spectra with the NIST library ver 2.0.f and the literature; some were confirmed by co-injection of standards (camphene, β-caryophyllene, α-humulene, linalool, α-phellandrene, α-pinene, β-pinene, γ-terpinene), and the RI were calculated for the constituents separated on the HP-5 column from the C8 to C40 n-alkanes.

Contents are expressed as relative percentages determined by FID; each oil and extract was analysed in triplicate, the relative peak area percentages being the mean of the three independent measurements ± standard deviation, and the final number of constituents adds the compounds identified on both columns to those detected on one only.

What did Vihanova et al. (2023) report for the pericarp essential oil?

In the C. hystrix essential oil, 38 constituents were identified on the HP-5 column and 50 compounds detected on the DB-HeavyWAX column.

According to Table 2, whose content columns are headed HP-5 MS and DB-Wax, the relative peak area percentages of the pericarp essential oil on the HP-5 MS column were: Sabinene 9.94 ± 0.22, β-Pinene 29.95 ± 0.54, Limonene 24.54 ± 0.16.

The relative peak area percentages (HP-5 MS / DB-Wax) were: α-Pinene 2.93 ± 0.16 / 2.96 ± 0.09; β-Myrcene 1.20 ± 0.05 / 1.38 ± 0.02; p-Cymene 1.91 ± 0.01 / 2.34 ± 0.01; γ-Terpinene 1.67 ± 0.01 / 1.63 ± 0.02.

Table 2 also gives, for this oil (HP-5 MS / DB-Wax): Linalool oxide 1.55 ± 0.02 / 1.57 ± 0.03; Citronellal 1.38 ± 0.07 / 1.05 ± 0.04; Terpinen-4-ol 9.71 ± 0.16 / 9.07 ± 0.22; α-Terpineol 3.70 ± 0.09 / 3.62 ± 0.07.

For the same oil, Table 2 further gives (HP-5 MS / DB-Wax): α-Copaene 0.95 ± 0.03 / 0.75 ± 0.04; β-Cubebene 0.37 ± 0.01 / “-”; β-Caryophyllene 0.72 ± 0.02 / 0.57 ± 0.01; β-Cadinene 1.49 ± 0.04 / 1.06 ± 0.1.

What did Vihanova et al. (2023) report for the supercritical CO2 extract of the pericarp?

In the C. hystrix supercritical CO2 extract, 36 components were determined on the HP-5 column, amounting to 99.36 % of the extract, and 54 compounds identified on the DB-HeavyWAX column, amounting to 98.06 %; Table 2 gives the total identified as 99.36 ± 0.07 (HP-5 MS) and 98.06 ± 0.32 (DB-Wax).

According to Table 2, the relative peak area percentages of the extract (HP-5 MS / DB-Wax) were: α-Pinene 2.54 ± 0.25 / 2.52 ± 0.09; β-Myrcene 1.43 ± 0.06 / 1.58 ± 0.02; (Z)-Sabinene hydrate 0.78 ± 0.06 / 1.06 ± 0.02; Citronellal 5.21 ± 0.31 / 4.28 ± 0.25; α-Terpineol 0.98 ± 0.17 / 1 ± 0.04.

Other compounds of the extract were at (HP-5 MS / DB-Wax): p-Cymene 0.1 ± 0.01 / 0.21 ± 0.02; γ-Terpinene 0.08 ± 0 / 0.1 ± 0.01; Linalool oxide “-” / 0.05 ± 0.01; Terpinen-4-ol 0.36 ± 0.04 / 0.42 ± 0.02.

For the same extract, Table 2 further gives (HP-5 MS / DB-Wax): α-Copaene 1.43 ± 0.13 / 1.21 ± 0.12; β-Cubebene 1.04 ± 0.15 / “-”; β-Caryophyllene 1.12 ± 0.09 / 1.05 ± 0.09; β-Cadinene 1.75 ± 0.11 / 1.57 ± 0.07.

The furanocoumarin oxypeucedanin accounted for 2.96 % of the extract on the HP-5 column (2.96 ± 0.64 in Table 2) and was not detected on the DB-HeavyWAX column ("-" in Table 2); Table 2 gives Thunbergol at 1.79 ± 0.12 (HP-5 MS) and 1.4 ± 0 (DB-Wax) in this extract.

References

• Efendi D., Budiarto R., Poerwanto R., Santosa E., Agusta A., « Relationship among Agroclimatic Variables, Soil and Leaves Nutrient Status with the Yield and Main Composition of Kaffir Lime (Citrus hystrix DC) Leaves Essential Oil », Metabolites 2021;11(5):260, doi:10.3390/metabo11050260 — https://www.ebi.ac.uk/europepmc/webservices/rest/PMC8145034/fullTextXML
• Vihanova K., Urbanova K., Nguon S., Kokoska L., « Chemical Composition of Essential Oils and Supercritical Carbon Dioxide Extracts from Amomum kravanh, Citrus hystrix and Piper nigrum ‘Kampot’ », Molecules 2023;28(23):7748, doi:10.3390/molecules28237748 — https://www.ebi.ac.uk/europepmc/webservices/rest/PMC10708404/fullTextXML
• Govaerts R. (ed.), World Checklist of Vascular Plants (WCVP), Royal Botanic Gardens, Kew — https://sftp.kew.org/pub/data-repositories/WCVP/wcvp.zip