Characterization of volatile components from ginger plant at maturity and its value addition to ice cream (2024)

Sample collection

Authentic Rio De Janeiro variety of ginger cultivar was obtained from ICAR-IISR Calicut, Kerala. Freshly harvested ginger plants (10 nos) with rhizome, leaves, stem and flowers were collected (August to December) from Mysuru District, Karnataka. The different parts of the plant, such as rhizome, leaves, stem and flowers were separated, washed, air dried, weighed and were used for essential oil extraction.

Extraction and isolation of essential oils

Fresh rhizomes, stem, flowers and leaves were taken and washed with water to remove adhering mud particles. Before distillation, air-dried flowers, leaves, rhizome and stems (100g each) were cleaned separately and sliced. All samples were hydrodistilled in a Clevenger distillation apparatus (Wohlmuth et al. 2006) for 4–6h. The yield of essential oil was calculated on a dry weight basis.

The essential oils were collected in the sample tubes, dried with anhydrous sodium sulphate and stored at − 4°C for further analyses.

GC–MS analysis and identification of the constituents of the essential oils

The volatiles from the various parts of the ginger plant was extracted by Clevenger hydrodistillation (4–6h). Quantitative and qualitative analyses of the volatile oil from these plant parts of Zingiber officinale were carried out by GC and GC–MS (Philippe et al. 2012). The volatile oils, as well as n-alkanes standards (from C9 to C30), were analyzed using a Perkin-Elmer Turbomass Gold GC (Massachusetts, USA) provided with a quadrupole mass spectrometer. GC/FID analyses were performed using Methyl silicone column (50m × 0.2mm, 0.17m) fitted with a fused silica capillary column (30m × 0.25mm, film thickness 0.25μm). The conditions used were: temperature programming, 80–200°C at the rate of 5°C/min, held at 200 for 15min, flame ionization detector (FID) temperature 300°C, injection temperature 250°C, carrier gas: nitrogen at a flow rate of 1mL/min, split ratio of 1:75. Diluted samples (10/100, v/v, in acetone) and 1μL was injected manually under split mode. Retention indices were calculated, and mass spectra were identified by comparing their fragmentation pattern. Electronic integration measurements were calculated from percent compositions without considering relative response factors. The linear retention indices of the components were determined relative to the retention times of a series of n-alkanes (C9–C30) by matching the linear retention indices and mass spectra of peaks with those obtained from authentic samples and the NBS75K.L and NIST98.L libraries and published data (Adams 2007).

Preparation of freeze-dried ginger powder from the rhizome

After 270days of maturity, the fresh ginger rhizomes were harvested (5kg), washed, and was sliced using a slicer and placed for fruit crushing mill. The crushed fresh ginger was next subjected to the hydraulic press remove the ginger juice/water content and starch. The extracted ginger juice was centrifuged at 5000rpm to separate the starch content, which settled at the bottom, and the supernatant was used for lyophilization. Separated ginger juice (3L) was dehydrated by using freeze-drying/lyophilization at vacuum pressure 0.05mbar for 18h. Freeze-dried ginger powder was stored at 4°C and used for further use

Extraction of oleoresin and estimation of gingerols from freeze-dried ginger sample

The dried ginger powder was loaded onto a glass column and steeped in ethanol (1:10) and rested for 2h and then eluted. The extract obtained was distilled using flash evaporator at 50 ± 2°C under reduced pressure (40 millibars) and stored at 4°C (AOAC 2000).

Analysis of [6]-gingerol by TLC:[6]-gingerol was estimated by thin-layer chromatography (TLC), Rf value was calculated, and quantitative study was carried out by UV-spectrophotometer method. Ginger oleoresin (0.05g) was dissolved in 0.5mL of diethyl ether. TLC chamber was filled with hexane and diethyl ether in the ratio of 1:1.5 (40:60) which has been thoroughly saturated with the solvent vapours. TenµL of the sample were spotted to the 20 × 20cm silica gel TLC plates (Merck, Germany) after dividing the plate into six equal parts. The plate was exposed for 5 to 10min to drive off the solvent and sprayed with Folin-Denis reagent. Two major blue spots developed, the spot with higher Rf (0.54 to 0.71) being waxes and colouring matter and spot with the lower Rf value (0.26 to 0.29) being [6]-gingerol. The area representing [6]-gingerol was scooped with a small stainless-steel spatula by encircling the spot as well as 0.1 to 0.2cm away from the actual spot. ThreemL of distilled water was added and shaken well in a test tube. OnemL Folin-Denis reagent was pipetted into the tube and mixed well. After 3 to 4min, 1mL saturated NaCO₃ was added, mixed thoroughly for 5min and kept for one h. Blank was prepared with approximately the same amount of all reagents without a sample. The optical density (OD) was read in a UV-spectrophotometer (UV-1800) Shimadzu at 725nm. The amount of [6]-gingerol was calculated against the standard graph derived by using vanillin at different concentrations.

where, X is graph reading for gingerol in 1mL solution in µg and Q is the quantity of extract in a spot.

Incorporation of gingerols in ice cream

The ginger ice cream was prepared by using 100g ready ice cream base (without any added flavour and colour), and then freeze-dried ginger extract at various concentrations added (Table1). This mixture was churned in an ice cream maker for 30min, until creamy. The ready ginger incorporated ice cream was transferred into containers stored at refrigerated temperatures for further studies. The physico-chemical and microbial qualities of the prepared ice cream was analyzed.

Colour measurement of ice cream with added ginger extracts

Colour of the ice creams with added ginger extracts along with control were measured using Hunter Colorimeter (Hunter Associates Laboratory, USA) (Hunt 1991). The change in colour was measured and compared with the three colour coordinates, namely, L*, a*, and b*. Where L* represents the lightness index, a* represents red-green, and b* represents yellow-blue colour components. The instrument was calibrated using a standard white, i.e. (L* = 90.70, a* = − 1.08. b* = 0.65 illuminate D 65 and view angle 10°C). Chroma indicates the purity of the colour or hue as measured along an axis. Hue angle visualizes how an average person sees the colour.

Texture measurement of ice cream with added ginger extracts

Quality characteristics of the prepared ice creams were carried out as reported by Alamprese et al. (2002) Firmness was determined by a Universal Texture Measuring Instrument (Mod. LLOYD-LR-5K) performing penetration tests on 50mL samples. A stainless steel conical probe (8mm diameter) connected to a 100N load cell was used, penetrating ice cream samples for 15mm, using a crosshead speed of 50mm/min. Results obtained are expressed as maximum load (N) at 15mm penetration, an average of at least ten measurements was considered (Moriano and Alamprese 2017).

Sensory analysis

Sensory analysis of ice cream with added ginger extracts was carried out by a trained panel in sensory booths (ISO 1998). Evaluations were conducted under white fluorescent light, with the booth area maintained at temperature 22 ± 2°C and RH 55 ± 5%. Samples were presented in porcelain plates coded with 3-digit random numbers, to the panellists. A glass of water was also presented to cleanse the palate in between the samples. Five samples of ice cream 1.Control (without gingerol), 2–5.with gingerol at increasing levels of 0.25%(S1), 0.50%(S2), 0.75%(S3) and 1% (S4)respectively were served to the panelists.

Quantitative descriptive analysis (QDA) method was employed for conducting a sensory analysis of the sample. Sensory evaluations of icecream samples were carried out for the attributes such as colour and appearance, texture, taste, flavour and overall quality by a panel of 12 panelists. A suitable scorecard comprising selected sensory attributes (descriptors) was formulated for this purpose. Panelists marked on a scale of 0-15cm to indicate the perceived intensity of each attribute listed on the scorecard. The scale was anchored at 1.25cm on either end, representing ‘Recognition Threshold’ and ‘Saturation Threshold’ respectively. The scores given for all the attributes for each sample were tabulated. Next, mean values were calculated for each attribute of a sample, representing the panel’s judgment about the sensory quality of the product. These are depicted graphically as “Sensory Profiles”.

Microbial analysis of ice cream

Microbiological assays were carried out according to the Food Safety and Standards Authority of India (FSSAI). 1:10 dilution of hom*ogenate (11 ± 0.1g into 99mL of 0.1% peptone water diluent) of the sample was prepared and mixed well. Decimal dilutions were made and incorporated into plate count agar (PCA) for the aerobic mesophilic bacterial count. For B. cereus and S. aureus 0.1mL of food hom*ogenate was evenly spread on MYP agar and Baird parker agar plates respectively, the plates were incubated for 24h at 35 ± 2°C. For the detection of coliforms, 1mL of food hom*ogenate and dilutions were inoculated into Violet red bile agar (VRBA) medium, and after solidification of the media, the plates were overlaid with 3 to 5mL of VRBA media and allowed to solidify.

The plates were incubated for 24h at 35 ± 2°C. Detection of Salmonella and Listeria monocytogenes was carried out by pre-enrichment, enrichment, and streaking on selective and differential media. For salmonella, 25 g of the sample was added to 225mL of the sterile buffered peptone water and incubated for 24h at 35°C. OnemL of the pre enriched sample was transferred to 10mL of Rappaport Versatile RV broth (incubation temperature 42 °C) and an additional 1mL to tetrathionate broth (incubate at 37 °C for 24 ± 2h). Loopful of incubated RV medium and tetrathionate broth were streaked on selective media plates of XLD, HEA and BSA. All the plates were incubated st 37°C for 24 ± 2h to 48 ± 2h. For L. monocytogenes 25g of the sample was mixed to 225mL of the sterile Half Frazer broth and incubated at 30°C for 24 ± 2h. One mL of the above culture was transferred to 9mL of Frazer broth and Incubated at 37°C for 48 ± 2h at 35–37°C. Cultures from both 24h culture of Half Frazer broth and 48h Frazer broth were streaked out on Modified Oxford Agar, and PALCAM agar and the plates were incubated at 35 ± 2C for 24h. Biochemical tests confirmed all the suspected pathogenic bacterial colonies are within the limits.

Statistical analysis

All analyses were carried out in triplicate. Duncan’s Multiple Range Test was applied to differentiate among the means of different samples (p ≤ 0.05) (Duncan 1957).

Table2

Biomass of ginger plant in different growth times after planting

Identification of volatile components

The essential oil from the ginger rhizome did not show any significant difference in terms of yield on maturity up to 270days the values ranged from 0.8mL at 150days and increased to 1.2mL at 270days. Though GC–MS profiles (Fig.1) were comparatively similar, major differences were observed in the amounts of individual compounds of volatile oil. The leaf and stem contained ten compounds, whereas oil extracted from flower contained more than 15 compounds (Fig.1a–c). The ginger rhizome contained more than 35 compounds in significant amounts. Compounds present in rhizome after 210days of maturity are significantly more than the compounds found in the 150th day of maturity. The flavour components, their concentrations, and calculated Kovats indices of the volatile oils from leaf, stem and flower are summarised in Table3. It can be observed that only ten major flavour components characterised leaf, stem and flower of Rio De Janeiro ginger variety. Major volatile compounds identified in fresh ginger rhizome includes Zingiberene (2–18%), sequiphellandrene (5–7%), ar-curcumin (3–12%), and other sesquiterpenes. Compounds in the rhizome persisted for 5months continuously after flowering (150–270days), and variations in their concentrations are shown in Table4. A total of 35 major flavour compounds were identified in the essential oils from the ginger rhizome, which constituted to about 75% of the total volatile components. Here we can observe the rise in the concentration of Zingiberene from 2 to 18% with maturity time, whereas in case of ar- curcumene we observed significant decrease from 12 to 3% of the compound (Table5). A higher number of compounds (49) were observed in the rhizome as compared to other parts.

The remaining compounds were either absent or present in low percentages at different parts of the ginger plant. Similar results were observed by Ravi Kiran et al. (2013), and they suggested that volatile oil composition depends upon the maturity stage and location. Studies carried out by Natarajan et al. (1972) with twenty-six varieties of ginger showed that the volatile oil content and ginger extract increased steadily after the fifth month. The primary major constituents of ginger oil were zingiberene (18–19%), ar-curcumin (12–13%), camphene (9–10%), α-feresene(9–10) and α-sesquiphellandrene (6–8%). Zingiberene has been reported by Singh et al. (2008) as the major constituent of ginger. In our study, also Zingiberene was observed to be the major volatile component of the rhizome, which increased from 2 to 18% as maturity advanced. In contrast, Agarwal et al. (2001) reported curcumin as the principal constituent. But our results showed that curcumin content reduced from 12 to 3% with an increase in maturity time. The variations in concentrations and contents of volatile compounds may be due to the disappearance of some components and appearance of others in different parts of the whole ginger plant. Our findings suggest that the variation in flavour compounds in ginger depended on the stages of maturity and the plant part. The variations in the distribution of volatile compounds depending upon the plant part are responsible for the quantitative and qualitative variations in different parts (Wannes et al. 2010). Various factors such as experimental methods, environmental conditions, genetic influence, ontogeny, variety and part of the plant used also cause variations in volatile compounds.

Estimation of gingerols from freeze-dried ginger powder for addition into ice cream

Fivekg of fresh ginger rhizomes yielded three litters of ginger juice after freeze-drying, resulted in 28g (9.3%) of powder. The freeze-dried ginger powder yielded 10.2% of oleoresin, which consists of 3.6 ± 0.2% of 6- gingerol.

Effect of incorporation of freeze-dried ginger extract on the colour & texture of ice cream

The ginger ice cream was prepared by using ready ice cream base, and then freeze-dried ginger extract at various concentrations (Table1). The prepared ice cream was analyzed for its physico-chemical and microbial quality.

Colour is an essential criterion for food acceptability. Results in Table6 show that L*, a*, and b* of ice cream are, L* decreased at 0.75% and 1.0% addition of ginger extract. Whereas a* at 1.0% addition, shows significant changes but incase of b* there are no changes. ΔE represents the total colour difference, which increased with the constant increase in addition to ginger extract. The firmness of the ice cream samples did not show any significant differences among the values (Table6). Hence no changes were observed in the firmness of ice cream samples with added ginger extracts. Similar results were observed in the sensory profile of the ice creams also (Fig.2).

Sensory results

Body and texture are essential properties of ice cream and key indicators of quality. The body can be referred to as the quality of whole ice cream, whereas texture can be understood as parts making up the whole. Body and texture of ice cream could be perceived through the senses of sight, mouthfeel, an integral component of texture, is sensed when ice cream is tasted in the mouth. Desirable textural attributes of ice cream are initial firmness with slight resistance and a distinct smoothness and creaminess in the mouth, as it melts. The textural measurements i.e, Firmness (Table6) also shows similar results.

The ice cream sample with gingerol had these desirable sensory attributes with the novelty of natural ginger flavour. Pinto et al. (2006) have reported the addition of ginger shreds at 4% levels had the edge over control with regard to sensory perception. In the present study, we have used freeze dried ginger concentrate and the colour was uniform and pleasant, with attractive visual appeal, which is an essential determinant for consumer acceptance and preference. Only marginal differences in instrumental colour parameters, especially L*, or lightness of the ice cream samples were observed (Table6). The total colour difference or DE showed that the colour increased with an increase in addition to the amount of ginger extract.

Similar results were observed in the sensory profile of the ice cream samples also, (Fig.2), off white colour was least in the control sample. At the same time, the highest was perceptible in S4 (1%), containing the highest level of gingerol among the test samples studied. In other words, control and S1 appeared lighter compared to S4. As the level of incorporation of gingerol increased, the perceived intensity of smoothness, milky aroma and sweetish aroma decreased with a corresponding increase in the perceived intensity of ginger-like aroma. Compared to control, there was a considerable decrease in the perceived intensity of creaminess and smoothness in S4. However, these changes in the sensory profiles of test samples (containing ginger extract), did not affect their overall quality to a large extent, compared to control. A control sample was rated to have a score of 9.3 while the test sample S1, S2, S3 and S4 had scores of 10.1, 9.1, 93 and 8.6 respectively for overall quality. This shows that there was no significant difference in the overall quality of the samples. Perceived intensity of ginger flavour was found to be desirable in S1 and S2, although a lingering sense of slight pungency was observed at the back of the throat, leading to the perception of ‘heat’.

Microbial quality

Based on the sensory analysis, sample 2 (S2) was taken into consideration, and microbial quality was evaluated. The microbial quality of the sample was compared with the FSSAI standards. According to the FSSAI standards the Aerobic plate count of the ice cream samples should not exceed 1 − 2 × 10⁵cfu/g, coliforms 10 − 1 × 10²cfu/g, S. aureus 10 − 1 × 10²cfu/g with the absence of L. monocytogenes, E. coli and Salmonella spp. in 25g of the samples. The flavoured ice cream sample contained 62 × 10⁴/g of the aerobic bacterial count, 75 × 10¹/g of coliform, 2 × 10¹/g of S. aureus and 8 × 10¹/g of B. cereus count. The sample was detected with no L. monocytogenes, E. coli and Salmonella spp. Since the care was taken to get raw material to be within acceptable quality the product of the study found microbiologically satisfactory.

Conflict of interest

Authors declare no conflict of interest in this work.

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• Adams RP. Identification of essential oil components by gas chromatography/mass spectrometry. 4. Carol Stream: Allured Publishing Corporation Carol Stream; 2007. [Google Scholar]
• Agarwal M, Walia S, Dhingra S, Khambay BPS. Insect growth inhibition, antifeedant and antifungal activity of compounds isolated/derived from Zingiber officinale Roscoe (ginger) rhizomes. Pest Manag Sci Former Pestic Sci. 2001;57:289–300. [PubMed] [Google Scholar]
• Alamprese C, Foschino R, Rossi M, Pompei C, Savani L. Survival of Lactobacillus johnsonii La1 and influence of its addition in retail-manufactured ice cream produced with different sugar and fat concentrations. Int Dairy J. 2002;12:201–208. [Google Scholar]
• An K, Zhao D, Wang Z, Wu J, Xu Y, Xiao G. Comparison of different drying methods on Chinese ginger (Zingiber officinale Roscoe): changes in volatiles, chemical profile, antioxidant properties, and microstructure. Food Chem. 2016;197:1292–1300. [PubMed] [Google Scholar]
• AOAC (2000) The association of official analytical chemists method 985.35. Official methods of analysis, (16th ed.) USA
• Bansod S, Rai M. Antifungal activity of essential oils from indian medicinal plants against human pathogenic Aspergillus fumigatus and A. niger. World J Med Sci. 2008;3:81–88. [Google Scholar]
• Chen CC, Ho CT. Gas chromatographic analysis of volatile components of ginger oil (Zingiber officinale Roscoe) extracted with liquid carbon dioxide. J Agric Food Chem. 1988;36:322–328. [Google Scholar]
• Chouhan S, Sharma K, Guleria S. Antimicrobial activity of some essential oils—present status and future perspectives. Medicines. 2017;4:58. [PMC free article] [PubMed] [Google Scholar]
• Connell DW, Sutherland MD. A re-examination of gingerol, shogaol, and zingerone, the pungent principles of ginger (Zingiber officinale Roscoe) Aust J Chem. 1969;22:1033–1043. [Google Scholar]
• Daudu OM, Sekoni AA, Ogundipe SO, Erakpotobor GT, Olugbemi TS. The effect of supplementation of enzyme on performance and some blood chemistry parameters in broiler finisher chickens fed ginger by-product meal (Zingiber officinale) Int J Biosci. 2012;2:59–65. [Google Scholar]
• Duncan DB. Multiple range tests for correlated and heteroscedastic means. Biometrics. 1957;13:164–176. [Google Scholar]
• El-Abhar HS, Hammad LN, Gawad HSA. Modulating effect of ginger extract on rats with ulcerative colitis. J Ethnopharmacol. 2008;118:367–372. [PubMed] [Google Scholar]
• El-Baroty SG, Abd El Baky HH, Farag SR, Saleh AM. Characterization of antioxidant and antimicrobial compounds of cinnamon and ginger essential oils. Afr J Biochem Res. 2012;4(6):167–174. [Google Scholar]
• Fawzi EM, Khalil AA, Afifi AF. Antifungal effect of some plant extracts on Alternaria alternata and Fusarium oxysporum. Afr J Biotechnol. 2009;8(11):259–2590. [Google Scholar]
• Habib SHM, Makpol S, Hamid NAA, Das S, Ngah WZW, Yusof YAM. Ginger extract (Zingiber officinale) has anti-cancer and anti-inflammatory effects on ethionine-induced hepatoma rats. Clinics. 2008;63(6):807–813. [PMC free article] [PubMed] [Google Scholar]
• Hossain M, Brunton N, Barry-Ryan C, Martin-Diana AB, Wilkinson M. Antioxidant activity of spice extracts and phenolics in comparison to synthetic antioxidants. Rasayan J Chem. 2008;1:751–756. [Google Scholar]
• Hunt RWG. Measuring Color-Ellis Horwood. New York. 1991;2:75–76. [Google Scholar]
• International Organization for Standardization [ISO] (1998) ISO 13299.2. Sensory analysis–methodology–general guidance for establishing a sensory profile
• Krittika N, Natta L, Orapin K. Antibacterial effect of five zingiberaceae essential oils. Molecules. 2007;12:2047–2060. [PMC free article] [PubMed] [Google Scholar] Retracted
• Ksouri R, Ksouri WM, Jallali I, Debez A, Magné C, Hiroko I, Abdelly C. Medicinal halophytes: potent source of health promoting biomolecules with medical, nutraceutical and food applications. Crit Rev Biotechnol. 2012;32(4):289–326. [PubMed] [Google Scholar]
• Mishra AP, Saklani S, Chandra S (2013) Estimation of gingerol content in different brand samples of ginger powder and their anti-oxidant activity: a comparative study. In: New horizons in pharmaceutical & biomedical sciences, vol. 5
• Moriano ME, Alamprese C. Organogels as novel ingredients for low saturated fat ice creams. LWT Food Sci Technol. 2017;86:371–376. [Google Scholar]
• Natarajan CP, Bai RP, Krishnamurthy MN, Raghavan B, Shankaracharya NB, Kuppuswamy S, Lewis YS. Chemical composition of ginger varieties and dehydration studies on ginger. J Food Sci Technol. 1972;9(3):120–124. [Google Scholar]
• Philippe S, Souaïbou F, Jean-Pierre N, Brice F, Paulin A, Issaka Y, Dominique S. Chemical composition and in vitro antifungal activity of Zingiber officinale essential oil against foodborne pathogens isolated from a traditional cheese wagashi produced in Benin. Int J Biosci. 2012;2(9):20–28. [Google Scholar]
• Pinto S, Rathour AK, Jana AH, Prajapati JP, Solanky MJ. Ginger shreds as flavouring in ice cream. Nat Prod Radiance. 2006;5(1):15–18. [Google Scholar]
• Rahath Kubra I, Jaganmohanrao L. An overview on inventions related to ginger processing and products for food and pharmaceutical applications. Recent Pat Food Nutr Agric. 2012;4(1):31–49. [PubMed] [Google Scholar]
• Ravi Kiran C, Chakka AK, Padmakumari Amma KP, Nirmala Menon A, Sree Kumar MM, Venugopalan VV. Essential oil composition of fresh ginger cultivars from North-East India. J Essent Oil Res. 2013;25(5):380–387. [Google Scholar]
• Sasidharan I, Menon AN. Comparative chemical composition and antimicrobial activity fresh & dry ginger oils (Zingiber officinale Roscoe) Int J Curr Pharm Res. 2010;2:40–43. [Google Scholar]
• Sebiomo A, Awofodu AD, Awosanya AO, Awotona FE, Ajayi AJ. Comparative studies of antibacterial effect of some antibiotics and ginger (Zingiber officinale) on two pathogenic bacteria. J Microbiol Antimicrob. 2011;3(1):18–22. [Google Scholar]
• Singh G, Kapoor IPS, Singh P, de Heluani CS, de Lampasona MP, Catalan CA. Chemistry, antioxidant and antimicrobial investigations on essential oil and oleoresins of Zingiber officinale. Food Chem Toxicol. 2008;46(10):3295–3302. [PubMed] [Google Scholar]
• Tapsell LC, Hemphill I, Cobiac L, Sullivan DR, Fenech M, Patch CS, Roodenrys S, Keogh JB, Clifton PM, Williams PG, Fazio VA (2006) Health benefits of herbs and spices: the past, the present, the future [PubMed]
• Variyar PS, Gholap AS, Thomas P. Effect of γ-irradiation on the volatile oil constituents of fresh ginger (Zingiber officinale) rhizome. Food Res Int. 1997;30(1):41–43. [Google Scholar]
• Wang WH, Wang ZM. Studies of commonly used traditional medicine-ginger. China J Chin Mater Med. 2005;30(20):1569–1573. [PubMed] [Google Scholar]
• Wannes WA, Mhamdi B, Sriti J, Jemia MB, Ouchikh O, Hamdaoui G, Marzouk B. Antioxidant activities of the essential oils and methanol extracts from myrtle (Myrtus communis var. italica L.) leaf, stem and flower. Food Chem Toxicol. 2010;48(5):1362–1370. [PubMed] [Google Scholar]
• White B. Ginger: an overview. Am Fam Physician. 2007;75(11):1689–1691. [PubMed] [Google Scholar]
• Wohlmuth H, Smith MK, Brooks LO, Myers SP, Leach DN. Essential oil composition of diploid and tetraploid clones of ginger (Zingiber officinale Roscoe) grown in Australia. J Agric Food Chem. 2006;54(4):1414–1419. [PubMed] [Google Scholar]