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The yield, composition and hydrodistillation kinetics of the essential oil of dill seeds (Anethi fructus) obtained by different hydrodistillation techniques
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The yield, composition and hydrodistillation kinetics of the essential oil of dill seeds (Anethii fructus) obtained by different hydrodistillation techniques Ljiljana P. Stanojevic´ a,∗ , Niko S. Radulovic´ b , Tatjana M. Djokic´ c , Biljana M. Stankovic´ a , Duˇsica P. Ilic´ a , Milorad D. Cakic´ a , Vesna D. Nikolic´ a a
Faculty of Technology, Leskovac, University of Niˇs, Serbia Faculty of Science and Mathematics, University of Niˇs, Niˇs, Serbia c The Academy of Criminalistic and Police Studies, Belgrade, Serbia b
a r t i c l e
i n f o
Article history: Received 21 July 2014 Received in revised form 27 October 2014 Accepted 30 October 2014 Available online xxx Keywords: Dill (Anethum graveolens L.) Essential oil Carvone Hydrodistillation techniques Hydrodistillation kinetics
a b s t r a c t In this work the impact of four different techniques of Clevenger-type hydrodistillation (technique I–IV) on the yield, hydrodistillation kinetics and composition of the essential oils of Anethum graveolens L. seeds was investigated. The highest oil yield, after five consecutive hydrodistillation runs (3.74 ml/100 g of plant material), was achieved by the utilization of filtrated (from plant material) water used in the previous hydrodistillation run plus newly added water in the subsequent runs (technique III). The hydrodistillation of dill seeds took place in two stages: a rapid, early distillation of the oil followed by a much slower second phase. Two kinetics models were successfully used to interpret the hydrodistillation rate of the essential oil of dill. Independent of the technique used, the oil contained the same components but in differing amounts as inferred from detailed gas chromatography–mass spectroscopy (GC–MS) analyses. Carvone was found to be the major component in all obtained oils. © 2014 Elsevier B.V. All rights reserved.
1. Introduction Dill (Anethum graveolens L.) is an aromatic spice plant from the genus Anethum of the family Apiaceae (Umbelliferae) (Leung and Foster, 2003). This plant is an important condiment crop with a characteristic aroma and odour (Pino et al., 1995). It is well known as a medicinal herb with antimicrobial, hypotensive, antihyperlipidemic, diuretic, antiemetic, laxative and spasmolytic effects (Koppula and Choi, 2011; Hosseinnzadeh et al., 2002; Tucakov, 1997). The medicinal parts of the plant are its seeds, fresh or dried leaves and the upper stem (Leung and Foster, 2003; Faber et al., 1997). Various plant parts of dill have different odours (Faber et al., 1997). Dill seeds contain the highest concentration of medicinal and aromatic compounds, but an appreciable amount is also present in the leaves and flowers (Koppula and Choi, 2011). The essential oils from dill seeds, leaves and herb were used as a flavouring agent in the food industry, especially for their characteristic aroma and odour (Jirovetz et al., 2003). Dill seeds are considered as a valuable
∗ Corresponding author. Tel.: +381 16247203; fax: +381 16242859. ´ E-mail addresses: [email protected], [email protected] (L.P. Stanojevic).
source of essential oil (Ortan et al., 2009). The main compounds of the herb essential oil are ␣-phellandrene and dill ether which are responsible for the typical herb odour. Besides ␣-phellandrene and dill ether, limonene and carvone are present in large amounts. Carvone is mainly responsible for the typical caraway note of the oils. This monoterpene ketone is the main component of the seeds essential oil (Faber et al., 1997). With 2–5% of the essential oil dill seeds are deemed to be rich in the essential oil (Leung and Foster, 2003). Carvone was reported to be the major constituent (20–60%) in a number of instances (Leung and Foster, 2003; Callan et al., 2007; R˘adulescu et al., 2010; Delaquis et al., 2002). Limonene, apiole, dill apiole, ␣-phelandrene, ␣-pinene, ␣-terpinene, 1,8-cineole, dihydro carvone and p-cymene are also present in the oil (Leung and Foster, 2003; Pino et al., 1995). Dill leaves and herb contain significantly less essential oil when compared to the seeds (0.5–1.5%) (Faber et al., 1997; Leung and Foster, 2003). Essential oils are used in pharmaceutical, cosmetic and food industries and as natural remedies (Bakkali et al., 2008). The yield, taste, flavour and chemical composition (amount and ratio of components) of essential oil depends on a number of parameters, such as plant variety, season, soil, environmental conditions, drying procedure, storage conditions, method of distillation, and the analytics used for identification of the compounds (Leung and Foster, 2003;
http://dx.doi.org/10.1016/j.indcrop.2014.10.067 0926-6690/© 2014 Elsevier B.V. All rights reserved.
´ L.P., et al., The yield, composition and hydrodistillation kinetics of the Please cite this article in press as: Stanojevic, essential oil of dill seeds (Anethii fructus) obtained by different hydrodistillation techniques. Ind. Crops Prod. (2014), http://dx.doi.org/10.1016/j.indcrop.2014.10.067
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Faber et al., 1997; Ghassemi-Golezani et al., 2008; Nautiyal and Tiwari, 2011; Jirovetz et al., 2003; Callan et al., 2007; Stanojevic´ et al., 2011; Stankovic´ et al., 2001, 2005, 2004). Despite of the generally successful practical hydrodistillation technology used to extract essential oils, there is still a need to consider a procedure or method in detail that would enable the production of essential oils at an optimum output. Each essential oil should be considered on its own due to its specificities including the type of the plant material used for the extraction and the varying chemical composition of the oil produced. The objective of this study was to investigate the influence of the hydrodistillation technique on the extraction of dill oil from A. graveolens seeds in terms of oil yield and oil quality (physical properties and chemical composition). Then a developed mass transfer mathematical model was validated with the experimental results to describe the process behaviour. Up to now many investigators have modelled the kinetics of essential oil hydrodistillation from plant material (Milojevic´ et al., 2013 and references cited therein). However, no data on the influence of different hydrodistillation techniques on the yield, composition or hydrodistillation kinetics of the essential oil from dill seeds can be found in the literature. In this work the essential oil from dill seeds was obtained by four different hydrodistillation techniques and the yields, as well as the composition of the resulting essential oils was compared. Also, the hydrodistillation kinetics were compared, with an aim to choose the optimal technique affording maximal oil yield. 2. Materials and methods 2.1. Plant material Dried dill (Anethum graveolens L.) seeds (Anethii fructus) were purchased from “Planta Mell” (Svrljig, Southeast Serbia). Nondisintegrated dill seeds were used for the investigations. The moisture content of dill seeds determined by drying at 105 ◦ C to a constant weight was 7.33%. The initial oil content in the dill seeds was 4.0 ml/100 g dry plant material. 2.2. Essential oil isolation – hydrodistillation Influence of the hydrodistillation hydromodule. A separate (per hydromodule) batch of 15 g of dill seeds was subjected to standard Clevenger-type hydrodistillation conditions (the condensed water was recirculated) with water used in the following ratios (w/v, g/cm3 ): 1:10, 1:15, 1:20 and 1:25. The oil yield (v/w) was recorded after hydrodistillation time of 5–180 min. Influence of hydrodistillation techniques. Four hydrodistillation techniques of essential oil from dill seeds were applied (Stankovic´ et al., 2004; Stanojevic´ et al., 2011). Technique I – Classic Clevenger-type hydrodistillation (cohobation) (Stankovic´ et al., 2004; Stanojevic´ et al., 2011). The amount of 15 g of seeds was suspended in 300 ml of water and subjected to Clevenger hydrodistillation. The essential oil volume was recorded after hydrodistillation time of 5–180 min. The data from five consecutive runs was used to calculate the average oil yield. Technique II (Stankovic´ et al., 2004). This technique is the same as technique I, only the condensate water was not cohobated, but it was saved and combined with fresh water to a volume of 300 ml for the subsequent distillation of a new batch of dill seeds (Stanojevic´ et al., 2011). A new quantity of plant material (15 g) was used for each successive distillation. The oil volume was recorded after hydrodistillation time of 5–120 min. This procedure was repeated in successive four distillation runs with a new quantity of plant material (15 g).
Technique III (Stankovic´ et al., 2004; Stanojevic´ et al., 2011). The same as technique I, only the residual water from a previous hydrodistillation was, after the separation of plant debris by vacuum filtration, mixed with a new amount of water (the total volume of the residual water from a previous run and the newly added one was adjusted to 300 ml) utilized for the next distillation of a new batch of dill seeds. A new batch of 15 g of seeds was subjected to each successive distillation run. The oil volume was recorded after hydrodistillation time of 5–180 min. This procedure was repeated in successive four distillation runs with a new quantity of plant material (15 g). Technique IV (Stankovic´ et al., 2004). The same as technique I, only the condensate and residue still water from previous distillation were combined and made up with unused water to a final volume of 300 ml, and used as such in the subsequent hydrodistillation of a new quantity of dill seeds. The oil volume was recorded after hydrodistillation time of 5–120 min. This procedure was repeated in successive four distillations with a new quantity of plant material (15 g). After the fifth run of each hydrodistillation technique (I-IV), isolated essential oils of the five runs (1–5) were separated, dried with Na2 SO4 (anhydrous), and used to determine the physicochemical properties and for GC–MS analysis. 2.3. Hydrodistillation kinetics models The hydrodistillation kinetics of the essential oil from dill seeds was modelled by two models (Table 1): the model of Ponomarev (Ponomarev, 1976; Stanojevic´ et al., 2011) (Model A) and a nonstationary diffusion model through the plant material (Veljkovic´ ´ 2002; Milojevic´ et al., 2008) (Model B). and Milenovic, Table 1 Hydrodistillation kinetics models of essential oil from dill seeds. Kinetics model Non-stationary diffusion model through the plant material (Model B) Model of Ponomarev (Model A)
Kinetics equation
Linearized form of equation
qi qi = (1 − b) · e−kt (1) ln = ln(1 − b) − k · t (2) q0 q0 q0 − qi = b + k · t (3) q0
q0 – the initial essential oil amount in the seeds (ml/100 g dry seeds), qi – the oil content in the seeds after the period t (ml/100 g of dry seeds), b – coefficient of the initial rapid stage of hydrodistillation, k – coefficient of the second slower stage of the hydrodistillation (min−1 ) and t – the duration of hydrodistillation (min).
2.4. Gas chromatography/mass spectrometry (GC/MS) analyses Gas chromatography-mass spectrometry analyses (GC/MS) – c´ were performed (in triplicate) according to Radulovic´ and Ðordevi (2014) on a Hewlett-Packard 6890N gas chromatograph coupled with a 5975B MS detector. A non-polar, low-bleed column DB-5MS (length 30 m, i.d. 0.25 mm, film thickness 0.25 m, 5% poly(methylphenylsiloxane), Agilent J&W, USA), programmed from 70 ◦ C to 290 ◦ C at 5 ◦ C/min and afterwards held isothermally for 10 min at 290 ◦ C, was used. Injector and interface temperatures were 250 ◦ C and 300 ◦ C, respectively. The flow of He was held constant at 1.0 ml/min starting from the first 30 s after the injection. The Et2 O solutions of the essential oil (1 mg/ml) samples (1 l) were – c, ´ split injected (40:1) in a pulsed mode (Radulovic´ and Ðordevi 2014). The operational conditions of the MS detector were: electron impact (EI) energy, 70 eV; ion source temperature, 230 ◦ C; recorded mass range m/z 35–650. The relative (%) oil composition was calculated from the total ion current peak areas without correction factors. Identification of oil components was done as described in – c´ (2014). Radulovic´ and Ðordevi
´ L.P., et al., The yield, composition and hydrodistillation kinetics of the Please cite this article in press as: Stanojevic, essential oil of dill seeds (Anethii fructus) obtained by different hydrodistillation techniques. Ind. Crops Prod. (2014), http://dx.doi.org/10.1016/j.indcrop.2014.10.067
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2.5. Physicochemical characteristics of dill oil Physicochemical characteristics (relative density, optical rotation, refractive index, and solubility in 90% ethanol, Table 9) of the dill oil were analyzed at 20 ◦ C using standard method presented in Pharmacopoeia Jugoslavica IV (1984). 3. Results and discussion 3.1. The influence of the hydrodistillation hydromodule on the dill oil yield The influence of the hydrodistillation hydromodule on the dill seeds oil yield is shown in Table 2. The yield of the essential oil increased with the hydromodule increase, reached a maximum and then decreased. The highest oil yields of 2.80 ml per 100 g of dry plant material (70.0% of the initial seed content of the oil) were obtained by the application of the 1: 20 (w/v) hydromodule for the duration of 180 min. This optimal hydromodule was used in subsequent experiments. Table 2 The influence of the hydromodule on the yield of the essential oil. Hydromodule (w/v)
1:10 1:15 1:20 1:25 a
Yield of essential oil ml/100 g dry plant material
%a
2.12 2.41 2.80 2.73
53.0 60.25 70.0 68.25
The initial essential oil yield from dill seeds.
The oil yield increase with the increasing hydromodule is most likely a consequence the reduced mass transfer resistance and an ameliorated water-seeds contact, which makes the volatiles readily available for hydrodistillation. A slight oil yield reduction in the 1:25 (w/v) hydromodule can be probably explained by
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solubilization and/or by chemical transformation involving water molecules of some constituents due to larger quantities of water present during the distillation (Milojevic´ et al., 2008). 3.2. The influence of the hydrodistillation technique on the yield of dill volatiles Fig. 1 shows the influence of the hydrodistillation time on the essential oil yield in a series of five distillation at different hydrodistillation techniques (techniques I–IV) and average oil yield from five hydrodistillation run. Maximal essential oil yield of 2.8 ml/100 g dry plant material (70% in regard to the initial oil content) obtained by technique I was achieved after 180 min (Fig. 1a). In five consecutive hydrodistillation runs by techniques II (Fig. 1b), III (Fig. 1c) and IV (Fig. 1d) the oil yield increased with the increased number of hydrodistillation runs. In the sixth hydrodistillation run the maximum oil yield is nearly the same as in the fifth hydrodistillation. Maximal essential oil yield of 2.59 ml/100 g dry plant material (64.75% in regard to the initial oil content) obtained by technique II was achieved after 120 min in the fifth hydrodistillation run (Fig. 1b). The yield of oil is lower by 7.5% than the yield achieved by technique I. In the case of Clevenger hydrodistillation (technique I), the condensate water returns to the process maintaining the optimal hydromodule (1:20 w/v) approximately constant, while in the technique II, the liquid phase in a distillation flask is reduced over time. In accordance with the results of hydromodule influence on oil yield investigations, decrease of hydromodule below optimal (1:20 w/v) during hydrodistillation, leads to the reduction of expected maximal oil yield, for hydromodule 1:20 w/v, to the one corresponding to hydromodule 1:12 m/v (approximately 110 ml of water, which is about 36% of liquid phase, was eliminated during the hydrodistillation process). In addition, a part of oil soluble components (hydrophilic component) and a part of oil droplets which are finely emulsified (water-insoluble) in the
Fig. 1. Effect of the hydrodistillation time on the oil yield in a series of five distillation (a – technique I, b – technique II, c – technique III, d – technique IV).
´ L.P., et al., The yield, composition and hydrodistillation kinetics of the Please cite this article in press as: Stanojevic, essential oil of dill seeds (Anethii fructus) obtained by different hydrodistillation techniques. Ind. Crops Prod. (2014), http://dx.doi.org/10.1016/j.indcrop.2014.10.067
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Table 3 The influence of the hydrodistillation methodology on the essential oil yield. Hydrodistillation technique
Technique I Technique II Technique III Technique IV
%a
ml/100 g dry plant material Yield of essential oil after the fifth hydrodistillation
Average yield of essential oil from five hydrodistillation
Yield of essential oil after the fifth hydrodistillation
Average yield of essential oil from five hydrodistillation
2.80 2.59 3.74 2.73
2.80 2.32 3.37 2.47
70.0 64.75 93.5 68.25
70.0 58.0 84.25 61.75
d.p.m. – dry plant material. a The initial essential oil yield (in %) from dill seeds.
condensate water were returned to the next hydrodistillation, so the oil yield increased in a series of five hydrodistillations. According to Fig. 1b, this was happening up to the fifth hydrodistillation, after which there was probably the highest amount of dissolved hydrophilic and emulsified hydrophobic components of oil in the condensate water. A hydromodule decrease during hydrodistillation had a decisive impact on the significant reduction of maximum oil yield obtained by this hydrodistillation methodology. The maximal yield of 3.74 ml of the essential oil per 100 g of seeds (93.5% in regard to the initial oil content) obtained by technique III was achieved after 180 min in the fifth hydrodistillation run, for constant, optimal hydromodule of 1:20 w/v (Fig. 1c). About 70.5% of the initial content of oil from the dill seeds was achieved in the first hydrodistillation run by technique III. The oil yield increased with the increasing number of hydrodistillation runs. This is probably the consequence of the use of water from the still flask in the subsequent distillations of a new batch of seeds (Stanojevic´ et al., 2011). The oil yields achieved after the fifth hydrodistillation run was higher by 25.13 and 30.75% of the oil yield achieved by technique I and II, respectively. The maximal essential oil yield of 2.73 ml/100 g dry plant material (68.25% in regard to the initial oil content) obtained by technique IV was achieved after 120 min in the fifth hydrodistillation run, for constant, optimal hydromodule of 1:20 w/v (Fig. 1d). For obtaining essential oil by technique IV the condensate and residue still water from previous distillation were combined and made up with fresh water to 300 ml for the distillation of a new batch of dill seeds. The condensate water was removed from the hydrodistillation process while reducing the hydromodule of the initial, optimal 1:20 w/v to 1:12 w/v. Decrease of hydromodule during hydrodistillation had a decisive impact on the reduction of maximum essential oil yield obtained by this hydrodistillation technique, as we have seen in the case of technique II. According to the results presented in Table 3, it can be concluded that the oil yield depends on the used hydrodistillation technique. The highest amount of the oil was obtained by technique III for 180 min of hydrodistillation. The difference in the oil yield is the result of using the residual still water from previous distillations in the subsequent distillation of fresh batch of seeds. The oil yield obtained by hydrodistillation technique IV is higher than the yield obtained by technique II and less than the yield obtained by the technique III. The highest yield of essential oil was expected by technique IV, compared to yields achieved by techniques I, II and III, just using the condensate water and residue still water from the previous distillation for immersing plant material in the next distillation. However, the reduction of the essential oil maximum yield due to the decrease of hydromodule during the process, from 1:20 w/v to 1:12 w/v, because of the singling out of condensate water from the process of hydrodistillation, is considerably higher compared to its increase due to use of the condensate and residue still water from the previous distillation for immersing plant material in further distillations.
3.3. Hydrodistillation kinetics Two hydrodistillation kinetics models were applied in the case of essential oil from dill seeds: the model of Ponomarev (Ponomarev, 1976) (Model A) and a non-stationary diffusion model ´ 2002; Milojevic´ et al., 2008) (Model B). For (Veljkovic´ and Milenovic, the four methodologies utilized, in five consecutive runs, Fig. 2(a–d) and Fig. 3(a–d) show the kinetics of the oil hydrodistillation from dill seeds and the average oil yields of the corresponding hydrodistillations, by kinetics models A and B, respectively. The models used to described the kinetics of essential oil hydrodistillation from dill seeds were based on a mechanism similar to the one which relates to the extractive matters extraction ´ 2002; Milojevic´ from plant material (Veljkovic´ and Milenovic, et al., 2008). The hydrodistillation curves show that there are two distinct periods of hydrodistillation (Fig. 2). The volatiles distilled from the surface of the seed cells in the initial phase (the fast oil hydrodistillation). In the second phase, a much less rapid oil hydrodistillation period, a slow molecular diffusion of the essential oil constituents from intracellular compartments occurred. The coefficient b, characterizes the fast hydrodistillation period (linear part of the hydrodistillation curve), while the coefficient k characterizes the slow hydrodistillation period (Eq. (3)). The highest hydrodistillation level of oil (93.5% in regard to the initial content of essential oil in plant material) was obtained by technique III, after 180 min in the fifth hydrodistillation run (Fig. 2). The non-stationary diffusion model of dill oil hydrodistillation was shown in Fig. 3. This model was also described by Milojevic´ et al. (2008) for modelling oil hydrodistillation from juniper. The coefficients b and k, the time of the fast period of hydrodistillation (FHT, min) and hydrodistillation levels (HL = 100(q0 − qi )/q0 ) for the essential oil were presented in Tables 4–7. In the first period (fast hydrodistillation), 61.1% (technique I), 57.5% (technique II), 83.1% technique III) and 58.8% (technique IV) of the oil constituents evaporated with water steam from the outer surface of seed cells (Tables 4–7). First period is characterized by a rapid increase of essential oil. A slow increase of oil yield occurred in the second, slow period of hydrodistillation. Modelling of the kinetics of essential oil hydrodistillation from dill seeds was in accordance with hydrodistillation kinetics of oil from lavender flowers (Stanojevic´ et al., 2011), juniper berries (Milojevic´ et al., 2008) and laurel leaves (Stanisavljevic´ et al., 2010). The coefficient k values in kinetics equations of hydrodistillation in a model of non-stationary diffusion are higher than those of coefficient k in Ponomarev kinetics hydrodistillation equations (Tables 4–7). Based on the results shown in the mentioned tables, it can be concluded that coefficients b in kinetics equations of essential oils hydrodistillation, by Ponomarev and non-stationary diffusion model, are slightly different. The results presented in Tables 4–7 show that both kinetics models can be used for modelling of essential oil hydrodistillation from dill seeds.
´ L.P., et al., The yield, composition and hydrodistillation kinetics of the Please cite this article in press as: Stanojevic, essential oil of dill seeds (Anethii fructus) obtained by different hydrodistillation techniques. Ind. Crops Prod. (2014), http://dx.doi.org/10.1016/j.indcrop.2014.10.067
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Fig. 2. Hydrodistillation kinetics of dill seeds essential oils (Model A) in five consecutive hydrodistillation runs by four hydrodistillation techniques (a – technique I, b – technique II, c – technique III, d – technique IV).
Fig. 3. Hydrodistillation kinetics of dill seeds essential oils (Model B) in five consecutive hydrodistillation runs by four hydrodistillation techniques (a – technique I, b – technique II, c – technique III, d – technique IV).
´ L.P., et al., The yield, composition and hydrodistillation kinetics of the Please cite this article in press as: Stanojevic, essential oil of dill seeds (Anethii fructus) obtained by different hydrodistillation techniques. Ind. Crops Prod. (2014), http://dx.doi.org/10.1016/j.indcrop.2014.10.067
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Table 4 The time of the fast hydrodistillation stage (FHT), the level of hydrodistillation (HL) and the values of b and k coefficients from the kinetic equations (technique I). Hydrodistillation run
I-1 I-2 I-3 I-4 I-5 Average value
FHT, min
45 45 45 45 45 45
HL, %
62.0 62.0 62.9 61.1 61.1 61.9
Model A
Model B
b
k × 104 , min−1
b
k × 103 , min−1
0.607 0.613 0.615 0.597 0.600 0.607
5.74 5.84 5.75 5.74 5.52 5.70
0.603 0.610 0.611 0.594 0.597 0.603
1.72 1.76 1.77 1.67 1.61 1.70
Table 5 The time of the fast hydrodistillation stage (FHT), the level of hydrodistillation (HL) and the values of b and k coefficients from the kinetic equations (technique II). Hydrodistillation run
II-1 II-2 II-3 II-4 II-5 Average value
FHT, min
30 30 30 30 30 30
HL, %
41.4 45.0 53.9 54.7 57.5 50.5
Model A
Model B
b
k × 10 , min
b
k × 103 , min−1
0.383 0.432 0.528 0.514 0.558 0.483
1.11 0.78 0.58 1.03 0.77 0.86
0.377 0.430 0.527 0.508 0.555 0.48
2.08 1.53 1.36 2.53 2.0 1.89
4
−1
Table 6 The time of the fast hydrodistillation stage (FHT), the level of hydrodistillation (HL) and the values of b and k coefficients from the kinetic equations (technique III). Hydrodistillation run
III-1 III-2 III-3 III-4 III-5 Average value
FHT, min
45 60 45 45 45 45
HL, %
62.0 66.5 75.5 81.8 83.1 73.8
Model A
Model B
b
k × 10 , min
b
k × 103 , min−1
0.613 0.678 0.719 0.801 0.806 0.72
5.84 6.04 9.52 7.12 7.81 7.56
0.610 0.672 0.688 0.778 0.770 0.705
1.76 2.85 5.49 5.81 7.34 3.77
4
−1
Table 7 The time of the fast hydrodistillation stage (FHT), the level of hydrodistillation (HL) and the values of b and k coefficients from the kinetic equations (technique IV). Hydrodistillation run
IV-1 IV-2 IV-3 IV-4 IV-5 Average value
FHT, min
30 30 30 30 30 30
HL, %
42.3 45.0 50.4 55.7 58.8 50.2
3.4. Influence of the hydrodistillation techniques on dill oil composition Detailed GC/MS analyses enabled the identification of 29 components of dill seed essential oil (Table 8). Although all oils contained the same 29 constituents, the quantitative composition of the essential oils depended on the used hydrodistillation technique. GC–MS analyses of the essential oils revealed that carvone was the most abundant component of all investigated oils (85.9, 88.8, 89 and 89.3% in the oils obtained by hydrodistillation technique I, II, III and IV, respectively), independent of the applied hydrodistillation techniques. The content of carvone in the essential oil from dill seeds from various regions was different: 50.1%, from Bulgaria (Jirovetz et al., 2003), 55.2% from India (Singh et al., 2005), 75.21% from Romania, 49.5% from Canada (Delaquis et al., 2002). Alongside carvone, limonene, cis-dihydrocarvone, trans-dihydrocarvone, cis-carveol and trans-carveol, all other dill seeds oil components were identified in much lower concentrations. The content of cis-dihydrocarvone, trans-dihydrocarvone and cis-carveol was slightly different in all obtained oils. The content of limonene was 5.1%, 2.1%, 0.9% and 1.4% in the oils obtained
Model A
Model B
b
k × 104 , min−1
b
k × 103 , min−1
0.394 0.410 0.473 0.521 0.548 0.468
1.05 1.57 1.32 1.20 1.11 1.27
0.389 0.396 0.463 0.512 0.538 0.458
2.0 3.35 3.10 3.10 3.04 2.91
by hydrodistillation techniques I, II, III and IV, respectively. Other investigators reported a higher content of limonene in dill seeds oil (20–50%) (de Carvalho and da Fonseca, 2006; Jirovetz et al., 2003; Delaquis et al., 2002; Singh et al., 2005) than the one in the dill seeds from Serbia. These changes of carvone and limonene content in the essential oil, and changes in the compositions of the oil are probably due to differing environmental conditions and the differences in the genetic makeup of the utilized seeds (Ghassemi-Golezani et al., 2008; Callan et al., 2007; Faber et al., 1997; Stanojevic´ et al., 2011). Especially important is the significantly higher content of carvone (85.9–89.3%), a bioactive component with an array of different biological activities (de Carvalho and da Fonseca, 2006; Bailer et al., 2001; Bakkali et al., 2008; Faber et al., 1997). The major components are believed to be mainly responsible for the biological activity of this particular essential oil (Bakkali et al., 2008; Bailer et al., 2001). The usage of carvone as a reversible suppressant of sprouting in stored potatoes or flower bulbs is probably its most important technical application (Bailer et al., 2001). Based on the results obtained in our investigation, the essential oil from dill seeds from Southeast Serbia (Svrljig) could be a potential natural source for the industrial production of carvone.
´ L.P., et al., The yield, composition and hydrodistillation kinetics of the Please cite this article in press as: Stanojevic, essential oil of dill seeds (Anethii fructus) obtained by different hydrodistillation techniques. Ind. Crops Prod. (2014), http://dx.doi.org/10.1016/j.indcrop.2014.10.067
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Table 8 The identified constituents of the dill seeds essential oil from four different hydrodistillation methodologies (I–IV). Rt/min
RI a
Component
IDc
Hydrodistillation technique I
II
III
IV
tr 2.1 tr tr tr tr tr tr tr tr tr 2.6 tr tr 2.5 tr 1.5 tr 2.3 88.8 tr tr tr tr tr tr tr tr tr 99.8
tr 0.9 tr tr 0.2 tr tr tr tr tr tr 2.8 tr tr 2.7 tr 1.6 tr 2.4 89.0 tr tr tr 0.3 tr tr tr tr tr 99.9
tr 1.4 tr tr 0.1 tr tr tr tr tr tr 2.7 tr tr 2.7 tr 1.4 tr 2.0 89.3 tr tr 0.1 0.2 tr tr tr tr tr 99.9
Content, % 5.821 5.923 5.923 7.243 7.399 7.997 8.263 8.351 8.361 9.616 9.826 9.897 9.923 9.923 10.072 10.383 10.409 10.736 10.761 11.134 11.346 11.704 11.865 12.127 12.183 13.938 17.967 20.252 23.087
1020 1024 1025 1089 1095 1119 1132 1133 1137 1184 1186 1191 1192 1193 1200 1212 1215 1226 1226 1239 1247 1266 1273 1282 1289 1356 1517 1620 1722
trb 5.1 tr tr tr tr tr tr tr tr tr 3.0 tr tr 2.7 tr 1.4 tr 1.8 85.9 tr tr tr tr tr tr tr tr tr 99.9
p-Cymene Limonene -Phellandrene p-Cymenene Linalool trans-p-Mentha-2,8-dien-1-ol cis-Limonene oxide cis-p-Mentha-2,8-dien-1-ol trans-Limonene oxide Dill ether ␣-Terpineol cis-Dihydro carvone Dihydro carveol neo-Dihydro carveol trans-Dihydro carvone iso-Dihydro carveol trans-Carveol neoiso-Dihydro carveol cis-Carveol Carvone p-Anis aldehyde Isopiperitenone trans-Carvone oxide trans-Anethole Thymol cis-Carvyl acetate Myristicin Dill apiole Neocnidilide (syn. Sedanolide) Total identified:
a,b,c a,b,c a,b,c a,b a,b,c a,b a,b a,b a,b a,b a,b,c a,b a,b a,b a,b a,b a,b a,b a,b,c a,b,c a,b,c a,b a,b a,b,c a,b,c a,b,c a,b,c a,b a,b
a
RI = Retention index. tr = trace amount (<0.05%). c ID = method of identification, a = compound identified by mass-spectra comparison, b = compound identity confirmed by retention index comparison with literature values, c = co-injection of a standard. b
3.5. Influence of the hydrodistillation techniques on the physicochemical properties of the dill oil Physicochemical characteristics the essential oils obtained in the four different methodologies of hydrodistillation are given in Table 9.
study of the yield, composition and hydrodistillation kinetics of the essential oil from dill seeds (Anethii fructus) obtained by four different techniques of Clevenger-type hydrodistillation (technique I–IV) was carried out. The obtained results showed that the essential oil yield, composition and hydrodistillation kinetics depend on the hydrodistillation technique used. The highest oil yield was obtained by hydrodistillation technique III (3.74 ml/100 g
Table 9 Physicochemical properties of essential oil from dill seeds obtained by four hydrodistillation techniques. Hydrodistillation technique
Relative density (d20 , g/ml)
Refractive index (nD 20 )
Optical rotation (◦ )
Solubility (volume parts of 90% ethanol per 1 ml of the essential oil)
Technique I Technique II Technique III Technique IV
0.899 0.896 0.902 0.897 0.895–0.910
1.487 1.484 1.489 1.485 1.481–1.492
+76 +74 +77 +75 +70 to +80
1.5 2 1.5 2 1 volume or more of 90% ethanol
a a
According to British Pharmacopoeia (2009).
The obtained pale-yellow essential oils had a pleasant typical dill seeds smell. The values of the relative density, refractive index and optical rotation for the oil differed only slightly from one technique to the other. The results agree fairly well with the literature data in the British Pharmacopoeia (2009). 4. Conclusion The goal of this study was envisaged to pinpoint the optimal hydrodistillation technique for the extraction of the essential oil of A. graveolens seeds. In order to achieve this goal a comparative
of dry plant material). Two hydrodistillation kinetics models of essential oil from dill seeds were described mathematically: model Ponomarev and non-stationary diffusion model. Quantitative composition of the resulting oils depended on the hydrodistillation technique used. The investigated oils, obtained by techniques I, II, III and IV contained carvone as the major constituent (85.9, 88.8, 89.0 and 89.3%, respectively). Besides carvone, limonene, cis-dihydrocarvone, trans-dihydrocarvone, cis-carveol and transcarveol, other oil components of dill seeds were identified in significantly lower amounts. Based on these results, an optimal hydrodistillation technique for the extraction of the essential oil
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from dill seeds with maximal yield and high carvone content could be devised. The results also suggest that the dill seeds’ essential oil from Southeast Serbia could be regarded as a potential natural source of bioactive carvone. Acknowledgement This work was supported under the Project on Development of Technology number TR-34012 by the Ministry of Education, Science and Technological Development of the Republic of Serbia. References Bailer, J., Aichinger, T., Hackl, G., Hueber, K., Dachler, M., 2001. Essential oil content and composition in commercially available dill cultivars in comparison to caraway. Ind. Crops Prod. 14, 229–239. Bakkali, F., Averbeck, S., Averbeck, D., Idaomar, M., 2008. Biological effects of essential oils – a review. Food Chem. Toxicol. 46, 446–475. British Pharmacopoeia 2009. London: Crown Copyright, 2008. Callan, N.W., Johnson, D.L., Westcott, M.P., Welty, L.E., 2007. Herb and oil composition of dill (Anethum graveolens L.): effects of crop maturity and plant density. Ind. Crops Prod. 25, 282–287. de Carvalho, C.C.C.R., da Fonseca, M.M.R., 2006. Carvone: why and how should one bother to produce this terpene. Food Chem. 95, 413–422. Delaquis, P.J., Stanich, K., Girard, B., Mazza, G., 2002. Antimicrobial activity of individual and mixed fractions of dill, cilantro, coriander and eucalyptus essential oils. Int. J. Food Microbiol. 74, 101–109. Faber, B., Bangert, K., Mosandl, A., 1997. GC-IRMS and enantioselective analysis in biochemical studies in dill (Anethum graveolens L.). Flavour Fragr. J. 12, 305–314. Ghassemi-Golezani, K., Andalibi, B., Zehtab-Salmasi, S., Saba, J., 2008. Effects of water stress during vegetative and reproductive stages on seed yield and essential oil content of dill (Anethum graveolens L.). J. Food Agric. Environ. 6, 282–284. Hosseinnzadeh, H., Karimi, G.R., Ameri, M., 2002. Effects of Anethum graveolens L. seed extracts on experimental gastric irritation models in mice. BMC Pharmacol. 2, 1471–2210. Jirovetz, L., Buchbauer, G., Stoyanova, A.S., Georgiev, E.V., Damianova, S.T., 2003. Composition, quality control, and antimicrobial activity of the essential oil of long-time stored dill (Anethum graveolens L.) seeds from Bulgaria. J. Agric. Food Chem. 51, 3854–3857. Koppula, S., Choi, D.K., 2011. Anethum Graveolens Linn (Umbelliferae) extract attenuates stress-induced urinary biochemical changes and improves cognition in scopolamine induced amnesic rats. Trop. J. Pharm. Res. 10, 47–54. Leung, A.Y., Foster, S., 2003. Encyclopedia of common natural ingredients (used in food, drugs, and cosmetics), Second edition. A John Wiley & Sons Inc., Hoboken, New Jersey.
´ S.Zˇ ., Radosavljevic, ´ D.B., Pavicevi ´ ´ V.P., Pejanovic, ´ S., Veljkovic, ´ V.B., 2013. Milojevic, c, Modeling the kinetics of essential oil hydrodistillation from plant materials. Hem. Ind. 67, 843–859. ´ S.Zˇ ., Stojanovic, ´ T.D., Palic, ´ R., Lazic, ´ M.L., Veljkovic, ´ V.B., 2008. Kinetics of Milojevic, distillation of essential oil from comminuted ripe juniper (Juniperus communis L.) berries. Biochem. Eng. J. 39, 547–553. Nautiyal, O.P., Tiwari, K.K., 2011. Extraction of dill seed oil (Anethum sowa) using supercritical carbon dioxide and comparison with hydrodistillation. Ind. Eng. Chem. Res. 50, 5723–5726. Ortan, A., Popescu, M.L., Gaita, A.L., Dinu-Pirvu, C., 2009. Contributions to the pharmacognostical study on Anethum graveolens Dill (Apiaceae). Rom. Biotechnol. Lett. 14, 4342–4348. Pharmacopoeia Jugoslavica, 1984. Ph. Jug.IV, vol. 2. Editio Quarta, Savezni zavod za zdravstvenu zaˇstitu, Beograd (in Serbian). Pino, J.A., Rosado, A., Goire, I., Roncal, E., 1995. Evaluation of flavor characteristic compounds in dill herb essential oil by sensory analysis and gas chromatography. J. Agric. Food Chem. 43, 1307–1309. Ponomarev, V.D., 1976. Ekstragirovanie lekarstvenogo syr’ya. Medicina, Moscow. R˘adulescu, V., Popescu, M.L., Ilies¸, D.-C., 2010. Chemical composition of the volatile oil from different plant parts of Anethum graveolens L. (Umbelliferae) cultivated in Romania. Farmacia 58, 594–600. – c, ´ N.S., Ðordevi ´ M., 2014. Chemical composition of the tuber essential oil Radulovic, from Helianthus tuberosus L. (Asteraceae). Chem. Biodivers. 11, 427–437. Singh, G., Maurya, S., de Lampasona, M.P., Catalan, C., 2005. Chemical constituents, antimicrobial investigations, and antioxidative potentials of Anethum graveolens L. essential oil and acetone extract Part 52. J. Food Sci. 70, 208–215. ´ I.T., Stojiˇcevic, ´ S.S., Veliˇckovic, ´ D.T., Ristic, ´ M.S., Lazic, ´ M.L., Veljkovic, ´ Stanisavljevic, V.B., 2010. Kinetics of hydrodistillation and chemical composition of essential ´ leaves. J. Essent. oil from cherry laurel (Prunus laurocerasus var. serbica Panˇcic) Oil Res. 22, 564–567. ˇ Stanojevic, ´ M.Z., Nikolic, ´ N.C., ´ Lj.P, Cakic, ´ M.D., 2004. The effect of Stankovic, hydrodistillation technique on the yield and composition of essential oil from the seed of Petroselinum crispum (Mill) Nym.ex.A.W.Hill. Hem. Ind. 58, 409–412. ˇ Cakic, ´ M.Z., Stanojevic, ´ Lj.P., Nikolic, ´ N.C., ´ M.D., 2005. Hydrodistillation Stankovic, kinetics and essential oil composition from fermented parsley seeds. Chem. Ind. Chem. Eng. Q 11, 177–182. ˇ Nikolic, ´ M.Z., Cakic, ´ M.D., Nikolic, ´ N.C., ´ G.S., 2001. The effect of the Stankovic, hydrodistillation technique on the yield and composition of the essential oil from the leaves of Mentha x verticillata L. Hem. Ind. 55, 389–393. ´ Lj., Stankovic, ´ M., Cakic, ´ M., Nikolic, ´ V., Nikolic, ´ Lj., Ilic, ´ D., Radulovic, ´ N., Stanojevic, 2011. The effect of hydrodistillation techniques on yield, kinetics, composition and antimicrobial activity of essential oils from flowers of Lavandula officinalis L. Hem. Ind. 65, 455–463. Tucakov, J., 1997. Leˇcenje biljem. RAD-Beograd, Beograd. ´ V., Milenovic, ´ D., 2002. Extraction of resinoids from St. John’s wort (HyperVeljkovic, icum perforatum L.) II Modelling of extraction kinetics. Hem. Ind. (Belgrade) 56, 60–67.
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The yield, composition and hydrodistillation kinetics of the essential oil of dill seeds (Anethii fructus) obtained by different hydrodistillation techniques Ljiljana P. Stanojevic´ a,∗ , Niko S. Radulovic´ b , Tatjana M. Djokic´ c , Biljana M. Stankovic´ a , Duˇsica P. Ilic´ a , Milorad D. Cakic´ a , Vesna D. Nikolic´ a a
Faculty of Technology, Leskovac, University of Niˇs, Serbia Faculty of Science and Mathematics, University of Niˇs, Niˇs, Serbia c The Academy of Criminalistic and Police Studies, Belgrade, Serbia b
a r t i c l e
i n f o
Article history: Received 21 July 2014 Received in revised form 27 October 2014 Accepted 30 October 2014 Available online xxx Keywords: Dill (Anethum graveolens L.) Essential oil Carvone Hydrodistillation techniques Hydrodistillation kinetics
a b s t r a c t In this work the impact of four different techniques of Clevenger-type hydrodistillation (technique I–IV) on the yield, hydrodistillation kinetics and composition of the essential oils of Anethum graveolens L. seeds was investigated. The highest oil yield, after five consecutive hydrodistillation runs (3.74 ml/100 g of plant material), was achieved by the utilization of filtrated (from plant material) water used in the previous hydrodistillation run plus newly added water in the subsequent runs (technique III). The hydrodistillation of dill seeds took place in two stages: a rapid, early distillation of the oil followed by a much slower second phase. Two kinetics models were successfully used to interpret the hydrodistillation rate of the essential oil of dill. Independent of the technique used, the oil contained the same components but in differing amounts as inferred from detailed gas chromatography–mass spectroscopy (GC–MS) analyses. Carvone was found to be the major component in all obtained oils. © 2014 Elsevier B.V. All rights reserved.
1. Introduction Dill (Anethum graveolens L.) is an aromatic spice plant from the genus Anethum of the family Apiaceae (Umbelliferae) (Leung and Foster, 2003). This plant is an important condiment crop with a characteristic aroma and odour (Pino et al., 1995). It is well known as a medicinal herb with antimicrobial, hypotensive, antihyperlipidemic, diuretic, antiemetic, laxative and spasmolytic effects (Koppula and Choi, 2011; Hosseinnzadeh et al., 2002; Tucakov, 1997). The medicinal parts of the plant are its seeds, fresh or dried leaves and the upper stem (Leung and Foster, 2003; Faber et al., 1997). Various plant parts of dill have different odours (Faber et al., 1997). Dill seeds contain the highest concentration of medicinal and aromatic compounds, but an appreciable amount is also present in the leaves and flowers (Koppula and Choi, 2011). The essential oils from dill seeds, leaves and herb were used as a flavouring agent in the food industry, especially for their characteristic aroma and odour (Jirovetz et al., 2003). Dill seeds are considered as a valuable
∗ Corresponding author. Tel.: +381 16247203; fax: +381 16242859. ´ E-mail addresses: [email protected], [email protected] (L.P. Stanojevic).
source of essential oil (Ortan et al., 2009). The main compounds of the herb essential oil are ␣-phellandrene and dill ether which are responsible for the typical herb odour. Besides ␣-phellandrene and dill ether, limonene and carvone are present in large amounts. Carvone is mainly responsible for the typical caraway note of the oils. This monoterpene ketone is the main component of the seeds essential oil (Faber et al., 1997). With 2–5% of the essential oil dill seeds are deemed to be rich in the essential oil (Leung and Foster, 2003). Carvone was reported to be the major constituent (20–60%) in a number of instances (Leung and Foster, 2003; Callan et al., 2007; R˘adulescu et al., 2010; Delaquis et al., 2002). Limonene, apiole, dill apiole, ␣-phelandrene, ␣-pinene, ␣-terpinene, 1,8-cineole, dihydro carvone and p-cymene are also present in the oil (Leung and Foster, 2003; Pino et al., 1995). Dill leaves and herb contain significantly less essential oil when compared to the seeds (0.5–1.5%) (Faber et al., 1997; Leung and Foster, 2003). Essential oils are used in pharmaceutical, cosmetic and food industries and as natural remedies (Bakkali et al., 2008). The yield, taste, flavour and chemical composition (amount and ratio of components) of essential oil depends on a number of parameters, such as plant variety, season, soil, environmental conditions, drying procedure, storage conditions, method of distillation, and the analytics used for identification of the compounds (Leung and Foster, 2003;
http://dx.doi.org/10.1016/j.indcrop.2014.10.067 0926-6690/© 2014 Elsevier B.V. All rights reserved.
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Faber et al., 1997; Ghassemi-Golezani et al., 2008; Nautiyal and Tiwari, 2011; Jirovetz et al., 2003; Callan et al., 2007; Stanojevic´ et al., 2011; Stankovic´ et al., 2001, 2005, 2004). Despite of the generally successful practical hydrodistillation technology used to extract essential oils, there is still a need to consider a procedure or method in detail that would enable the production of essential oils at an optimum output. Each essential oil should be considered on its own due to its specificities including the type of the plant material used for the extraction and the varying chemical composition of the oil produced. The objective of this study was to investigate the influence of the hydrodistillation technique on the extraction of dill oil from A. graveolens seeds in terms of oil yield and oil quality (physical properties and chemical composition). Then a developed mass transfer mathematical model was validated with the experimental results to describe the process behaviour. Up to now many investigators have modelled the kinetics of essential oil hydrodistillation from plant material (Milojevic´ et al., 2013 and references cited therein). However, no data on the influence of different hydrodistillation techniques on the yield, composition or hydrodistillation kinetics of the essential oil from dill seeds can be found in the literature. In this work the essential oil from dill seeds was obtained by four different hydrodistillation techniques and the yields, as well as the composition of the resulting essential oils was compared. Also, the hydrodistillation kinetics were compared, with an aim to choose the optimal technique affording maximal oil yield. 2. Materials and methods 2.1. Plant material Dried dill (Anethum graveolens L.) seeds (Anethii fructus) were purchased from “Planta Mell” (Svrljig, Southeast Serbia). Nondisintegrated dill seeds were used for the investigations. The moisture content of dill seeds determined by drying at 105 ◦ C to a constant weight was 7.33%. The initial oil content in the dill seeds was 4.0 ml/100 g dry plant material. 2.2. Essential oil isolation – hydrodistillation Influence of the hydrodistillation hydromodule. A separate (per hydromodule) batch of 15 g of dill seeds was subjected to standard Clevenger-type hydrodistillation conditions (the condensed water was recirculated) with water used in the following ratios (w/v, g/cm3 ): 1:10, 1:15, 1:20 and 1:25. The oil yield (v/w) was recorded after hydrodistillation time of 5–180 min. Influence of hydrodistillation techniques. Four hydrodistillation techniques of essential oil from dill seeds were applied (Stankovic´ et al., 2004; Stanojevic´ et al., 2011). Technique I – Classic Clevenger-type hydrodistillation (cohobation) (Stankovic´ et al., 2004; Stanojevic´ et al., 2011). The amount of 15 g of seeds was suspended in 300 ml of water and subjected to Clevenger hydrodistillation. The essential oil volume was recorded after hydrodistillation time of 5–180 min. The data from five consecutive runs was used to calculate the average oil yield. Technique II (Stankovic´ et al., 2004). This technique is the same as technique I, only the condensate water was not cohobated, but it was saved and combined with fresh water to a volume of 300 ml for the subsequent distillation of a new batch of dill seeds (Stanojevic´ et al., 2011). A new quantity of plant material (15 g) was used for each successive distillation. The oil volume was recorded after hydrodistillation time of 5–120 min. This procedure was repeated in successive four distillation runs with a new quantity of plant material (15 g).
Technique III (Stankovic´ et al., 2004; Stanojevic´ et al., 2011). The same as technique I, only the residual water from a previous hydrodistillation was, after the separation of plant debris by vacuum filtration, mixed with a new amount of water (the total volume of the residual water from a previous run and the newly added one was adjusted to 300 ml) utilized for the next distillation of a new batch of dill seeds. A new batch of 15 g of seeds was subjected to each successive distillation run. The oil volume was recorded after hydrodistillation time of 5–180 min. This procedure was repeated in successive four distillation runs with a new quantity of plant material (15 g). Technique IV (Stankovic´ et al., 2004). The same as technique I, only the condensate and residue still water from previous distillation were combined and made up with unused water to a final volume of 300 ml, and used as such in the subsequent hydrodistillation of a new quantity of dill seeds. The oil volume was recorded after hydrodistillation time of 5–120 min. This procedure was repeated in successive four distillations with a new quantity of plant material (15 g). After the fifth run of each hydrodistillation technique (I-IV), isolated essential oils of the five runs (1–5) were separated, dried with Na2 SO4 (anhydrous), and used to determine the physicochemical properties and for GC–MS analysis. 2.3. Hydrodistillation kinetics models The hydrodistillation kinetics of the essential oil from dill seeds was modelled by two models (Table 1): the model of Ponomarev (Ponomarev, 1976; Stanojevic´ et al., 2011) (Model A) and a nonstationary diffusion model through the plant material (Veljkovic´ ´ 2002; Milojevic´ et al., 2008) (Model B). and Milenovic, Table 1 Hydrodistillation kinetics models of essential oil from dill seeds. Kinetics model Non-stationary diffusion model through the plant material (Model B) Model of Ponomarev (Model A)
Kinetics equation
Linearized form of equation
qi qi = (1 − b) · e−kt (1) ln = ln(1 − b) − k · t (2) q0 q0 q0 − qi = b + k · t (3) q0
q0 – the initial essential oil amount in the seeds (ml/100 g dry seeds), qi – the oil content in the seeds after the period t (ml/100 g of dry seeds), b – coefficient of the initial rapid stage of hydrodistillation, k – coefficient of the second slower stage of the hydrodistillation (min−1 ) and t – the duration of hydrodistillation (min).
2.4. Gas chromatography/mass spectrometry (GC/MS) analyses Gas chromatography-mass spectrometry analyses (GC/MS) – c´ were performed (in triplicate) according to Radulovic´ and Ðordevi (2014) on a Hewlett-Packard 6890N gas chromatograph coupled with a 5975B MS detector. A non-polar, low-bleed column DB-5MS (length 30 m, i.d. 0.25 mm, film thickness 0.25 m, 5% poly(methylphenylsiloxane), Agilent J&W, USA), programmed from 70 ◦ C to 290 ◦ C at 5 ◦ C/min and afterwards held isothermally for 10 min at 290 ◦ C, was used. Injector and interface temperatures were 250 ◦ C and 300 ◦ C, respectively. The flow of He was held constant at 1.0 ml/min starting from the first 30 s after the injection. The Et2 O solutions of the essential oil (1 mg/ml) samples (1 l) were – c, ´ split injected (40:1) in a pulsed mode (Radulovic´ and Ðordevi 2014). The operational conditions of the MS detector were: electron impact (EI) energy, 70 eV; ion source temperature, 230 ◦ C; recorded mass range m/z 35–650. The relative (%) oil composition was calculated from the total ion current peak areas without correction factors. Identification of oil components was done as described in – c´ (2014). Radulovic´ and Ðordevi
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2.5. Physicochemical characteristics of dill oil Physicochemical characteristics (relative density, optical rotation, refractive index, and solubility in 90% ethanol, Table 9) of the dill oil were analyzed at 20 ◦ C using standard method presented in Pharmacopoeia Jugoslavica IV (1984). 3. Results and discussion 3.1. The influence of the hydrodistillation hydromodule on the dill oil yield The influence of the hydrodistillation hydromodule on the dill seeds oil yield is shown in Table 2. The yield of the essential oil increased with the hydromodule increase, reached a maximum and then decreased. The highest oil yields of 2.80 ml per 100 g of dry plant material (70.0% of the initial seed content of the oil) were obtained by the application of the 1: 20 (w/v) hydromodule for the duration of 180 min. This optimal hydromodule was used in subsequent experiments. Table 2 The influence of the hydromodule on the yield of the essential oil. Hydromodule (w/v)
1:10 1:15 1:20 1:25 a
Yield of essential oil ml/100 g dry plant material
%a
2.12 2.41 2.80 2.73
53.0 60.25 70.0 68.25
The initial essential oil yield from dill seeds.
The oil yield increase with the increasing hydromodule is most likely a consequence the reduced mass transfer resistance and an ameliorated water-seeds contact, which makes the volatiles readily available for hydrodistillation. A slight oil yield reduction in the 1:25 (w/v) hydromodule can be probably explained by
3
solubilization and/or by chemical transformation involving water molecules of some constituents due to larger quantities of water present during the distillation (Milojevic´ et al., 2008). 3.2. The influence of the hydrodistillation technique on the yield of dill volatiles Fig. 1 shows the influence of the hydrodistillation time on the essential oil yield in a series of five distillation at different hydrodistillation techniques (techniques I–IV) and average oil yield from five hydrodistillation run. Maximal essential oil yield of 2.8 ml/100 g dry plant material (70% in regard to the initial oil content) obtained by technique I was achieved after 180 min (Fig. 1a). In five consecutive hydrodistillation runs by techniques II (Fig. 1b), III (Fig. 1c) and IV (Fig. 1d) the oil yield increased with the increased number of hydrodistillation runs. In the sixth hydrodistillation run the maximum oil yield is nearly the same as in the fifth hydrodistillation. Maximal essential oil yield of 2.59 ml/100 g dry plant material (64.75% in regard to the initial oil content) obtained by technique II was achieved after 120 min in the fifth hydrodistillation run (Fig. 1b). The yield of oil is lower by 7.5% than the yield achieved by technique I. In the case of Clevenger hydrodistillation (technique I), the condensate water returns to the process maintaining the optimal hydromodule (1:20 w/v) approximately constant, while in the technique II, the liquid phase in a distillation flask is reduced over time. In accordance with the results of hydromodule influence on oil yield investigations, decrease of hydromodule below optimal (1:20 w/v) during hydrodistillation, leads to the reduction of expected maximal oil yield, for hydromodule 1:20 w/v, to the one corresponding to hydromodule 1:12 m/v (approximately 110 ml of water, which is about 36% of liquid phase, was eliminated during the hydrodistillation process). In addition, a part of oil soluble components (hydrophilic component) and a part of oil droplets which are finely emulsified (water-insoluble) in the
Fig. 1. Effect of the hydrodistillation time on the oil yield in a series of five distillation (a – technique I, b – technique II, c – technique III, d – technique IV).
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Table 3 The influence of the hydrodistillation methodology on the essential oil yield. Hydrodistillation technique
Technique I Technique II Technique III Technique IV
%a
ml/100 g dry plant material Yield of essential oil after the fifth hydrodistillation
Average yield of essential oil from five hydrodistillation
Yield of essential oil after the fifth hydrodistillation
Average yield of essential oil from five hydrodistillation
2.80 2.59 3.74 2.73
2.80 2.32 3.37 2.47
70.0 64.75 93.5 68.25
70.0 58.0 84.25 61.75
d.p.m. – dry plant material. a The initial essential oil yield (in %) from dill seeds.
condensate water were returned to the next hydrodistillation, so the oil yield increased in a series of five hydrodistillations. According to Fig. 1b, this was happening up to the fifth hydrodistillation, after which there was probably the highest amount of dissolved hydrophilic and emulsified hydrophobic components of oil in the condensate water. A hydromodule decrease during hydrodistillation had a decisive impact on the significant reduction of maximum oil yield obtained by this hydrodistillation methodology. The maximal yield of 3.74 ml of the essential oil per 100 g of seeds (93.5% in regard to the initial oil content) obtained by technique III was achieved after 180 min in the fifth hydrodistillation run, for constant, optimal hydromodule of 1:20 w/v (Fig. 1c). About 70.5% of the initial content of oil from the dill seeds was achieved in the first hydrodistillation run by technique III. The oil yield increased with the increasing number of hydrodistillation runs. This is probably the consequence of the use of water from the still flask in the subsequent distillations of a new batch of seeds (Stanojevic´ et al., 2011). The oil yields achieved after the fifth hydrodistillation run was higher by 25.13 and 30.75% of the oil yield achieved by technique I and II, respectively. The maximal essential oil yield of 2.73 ml/100 g dry plant material (68.25% in regard to the initial oil content) obtained by technique IV was achieved after 120 min in the fifth hydrodistillation run, for constant, optimal hydromodule of 1:20 w/v (Fig. 1d). For obtaining essential oil by technique IV the condensate and residue still water from previous distillation were combined and made up with fresh water to 300 ml for the distillation of a new batch of dill seeds. The condensate water was removed from the hydrodistillation process while reducing the hydromodule of the initial, optimal 1:20 w/v to 1:12 w/v. Decrease of hydromodule during hydrodistillation had a decisive impact on the reduction of maximum essential oil yield obtained by this hydrodistillation technique, as we have seen in the case of technique II. According to the results presented in Table 3, it can be concluded that the oil yield depends on the used hydrodistillation technique. The highest amount of the oil was obtained by technique III for 180 min of hydrodistillation. The difference in the oil yield is the result of using the residual still water from previous distillations in the subsequent distillation of fresh batch of seeds. The oil yield obtained by hydrodistillation technique IV is higher than the yield obtained by technique II and less than the yield obtained by the technique III. The highest yield of essential oil was expected by technique IV, compared to yields achieved by techniques I, II and III, just using the condensate water and residue still water from the previous distillation for immersing plant material in the next distillation. However, the reduction of the essential oil maximum yield due to the decrease of hydromodule during the process, from 1:20 w/v to 1:12 w/v, because of the singling out of condensate water from the process of hydrodistillation, is considerably higher compared to its increase due to use of the condensate and residue still water from the previous distillation for immersing plant material in further distillations.
3.3. Hydrodistillation kinetics Two hydrodistillation kinetics models were applied in the case of essential oil from dill seeds: the model of Ponomarev (Ponomarev, 1976) (Model A) and a non-stationary diffusion model ´ 2002; Milojevic´ et al., 2008) (Model B). For (Veljkovic´ and Milenovic, the four methodologies utilized, in five consecutive runs, Fig. 2(a–d) and Fig. 3(a–d) show the kinetics of the oil hydrodistillation from dill seeds and the average oil yields of the corresponding hydrodistillations, by kinetics models A and B, respectively. The models used to described the kinetics of essential oil hydrodistillation from dill seeds were based on a mechanism similar to the one which relates to the extractive matters extraction ´ 2002; Milojevic´ from plant material (Veljkovic´ and Milenovic, et al., 2008). The hydrodistillation curves show that there are two distinct periods of hydrodistillation (Fig. 2). The volatiles distilled from the surface of the seed cells in the initial phase (the fast oil hydrodistillation). In the second phase, a much less rapid oil hydrodistillation period, a slow molecular diffusion of the essential oil constituents from intracellular compartments occurred. The coefficient b, characterizes the fast hydrodistillation period (linear part of the hydrodistillation curve), while the coefficient k characterizes the slow hydrodistillation period (Eq. (3)). The highest hydrodistillation level of oil (93.5% in regard to the initial content of essential oil in plant material) was obtained by technique III, after 180 min in the fifth hydrodistillation run (Fig. 2). The non-stationary diffusion model of dill oil hydrodistillation was shown in Fig. 3. This model was also described by Milojevic´ et al. (2008) for modelling oil hydrodistillation from juniper. The coefficients b and k, the time of the fast period of hydrodistillation (FHT, min) and hydrodistillation levels (HL = 100(q0 − qi )/q0 ) for the essential oil were presented in Tables 4–7. In the first period (fast hydrodistillation), 61.1% (technique I), 57.5% (technique II), 83.1% technique III) and 58.8% (technique IV) of the oil constituents evaporated with water steam from the outer surface of seed cells (Tables 4–7). First period is characterized by a rapid increase of essential oil. A slow increase of oil yield occurred in the second, slow period of hydrodistillation. Modelling of the kinetics of essential oil hydrodistillation from dill seeds was in accordance with hydrodistillation kinetics of oil from lavender flowers (Stanojevic´ et al., 2011), juniper berries (Milojevic´ et al., 2008) and laurel leaves (Stanisavljevic´ et al., 2010). The coefficient k values in kinetics equations of hydrodistillation in a model of non-stationary diffusion are higher than those of coefficient k in Ponomarev kinetics hydrodistillation equations (Tables 4–7). Based on the results shown in the mentioned tables, it can be concluded that coefficients b in kinetics equations of essential oils hydrodistillation, by Ponomarev and non-stationary diffusion model, are slightly different. The results presented in Tables 4–7 show that both kinetics models can be used for modelling of essential oil hydrodistillation from dill seeds.
´ L.P., et al., The yield, composition and hydrodistillation kinetics of the Please cite this article in press as: Stanojevic, essential oil of dill seeds (Anethii fructus) obtained by different hydrodistillation techniques. Ind. Crops Prod. (2014), http://dx.doi.org/10.1016/j.indcrop.2014.10.067
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Fig. 2. Hydrodistillation kinetics of dill seeds essential oils (Model A) in five consecutive hydrodistillation runs by four hydrodistillation techniques (a – technique I, b – technique II, c – technique III, d – technique IV).
Fig. 3. Hydrodistillation kinetics of dill seeds essential oils (Model B) in five consecutive hydrodistillation runs by four hydrodistillation techniques (a – technique I, b – technique II, c – technique III, d – technique IV).
´ L.P., et al., The yield, composition and hydrodistillation kinetics of the Please cite this article in press as: Stanojevic, essential oil of dill seeds (Anethii fructus) obtained by different hydrodistillation techniques. Ind. Crops Prod. (2014), http://dx.doi.org/10.1016/j.indcrop.2014.10.067
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Table 4 The time of the fast hydrodistillation stage (FHT), the level of hydrodistillation (HL) and the values of b and k coefficients from the kinetic equations (technique I). Hydrodistillation run
I-1 I-2 I-3 I-4 I-5 Average value
FHT, min
45 45 45 45 45 45
HL, %
62.0 62.0 62.9 61.1 61.1 61.9
Model A
Model B
b
k × 104 , min−1
b
k × 103 , min−1
0.607 0.613 0.615 0.597 0.600 0.607
5.74 5.84 5.75 5.74 5.52 5.70
0.603 0.610 0.611 0.594 0.597 0.603
1.72 1.76 1.77 1.67 1.61 1.70
Table 5 The time of the fast hydrodistillation stage (FHT), the level of hydrodistillation (HL) and the values of b and k coefficients from the kinetic equations (technique II). Hydrodistillation run
II-1 II-2 II-3 II-4 II-5 Average value
FHT, min
30 30 30 30 30 30
HL, %
41.4 45.0 53.9 54.7 57.5 50.5
Model A
Model B
b
k × 10 , min
b
k × 103 , min−1
0.383 0.432 0.528 0.514 0.558 0.483
1.11 0.78 0.58 1.03 0.77 0.86
0.377 0.430 0.527 0.508 0.555 0.48
2.08 1.53 1.36 2.53 2.0 1.89
4
−1
Table 6 The time of the fast hydrodistillation stage (FHT), the level of hydrodistillation (HL) and the values of b and k coefficients from the kinetic equations (technique III). Hydrodistillation run
III-1 III-2 III-3 III-4 III-5 Average value
FHT, min
45 60 45 45 45 45
HL, %
62.0 66.5 75.5 81.8 83.1 73.8
Model A
Model B
b
k × 10 , min
b
k × 103 , min−1
0.613 0.678 0.719 0.801 0.806 0.72
5.84 6.04 9.52 7.12 7.81 7.56
0.610 0.672 0.688 0.778 0.770 0.705
1.76 2.85 5.49 5.81 7.34 3.77
4
−1
Table 7 The time of the fast hydrodistillation stage (FHT), the level of hydrodistillation (HL) and the values of b and k coefficients from the kinetic equations (technique IV). Hydrodistillation run
IV-1 IV-2 IV-3 IV-4 IV-5 Average value
FHT, min
30 30 30 30 30 30
HL, %
42.3 45.0 50.4 55.7 58.8 50.2
3.4. Influence of the hydrodistillation techniques on dill oil composition Detailed GC/MS analyses enabled the identification of 29 components of dill seed essential oil (Table 8). Although all oils contained the same 29 constituents, the quantitative composition of the essential oils depended on the used hydrodistillation technique. GC–MS analyses of the essential oils revealed that carvone was the most abundant component of all investigated oils (85.9, 88.8, 89 and 89.3% in the oils obtained by hydrodistillation technique I, II, III and IV, respectively), independent of the applied hydrodistillation techniques. The content of carvone in the essential oil from dill seeds from various regions was different: 50.1%, from Bulgaria (Jirovetz et al., 2003), 55.2% from India (Singh et al., 2005), 75.21% from Romania, 49.5% from Canada (Delaquis et al., 2002). Alongside carvone, limonene, cis-dihydrocarvone, trans-dihydrocarvone, cis-carveol and trans-carveol, all other dill seeds oil components were identified in much lower concentrations. The content of cis-dihydrocarvone, trans-dihydrocarvone and cis-carveol was slightly different in all obtained oils. The content of limonene was 5.1%, 2.1%, 0.9% and 1.4% in the oils obtained
Model A
Model B
b
k × 104 , min−1
b
k × 103 , min−1
0.394 0.410 0.473 0.521 0.548 0.468
1.05 1.57 1.32 1.20 1.11 1.27
0.389 0.396 0.463 0.512 0.538 0.458
2.0 3.35 3.10 3.10 3.04 2.91
by hydrodistillation techniques I, II, III and IV, respectively. Other investigators reported a higher content of limonene in dill seeds oil (20–50%) (de Carvalho and da Fonseca, 2006; Jirovetz et al., 2003; Delaquis et al., 2002; Singh et al., 2005) than the one in the dill seeds from Serbia. These changes of carvone and limonene content in the essential oil, and changes in the compositions of the oil are probably due to differing environmental conditions and the differences in the genetic makeup of the utilized seeds (Ghassemi-Golezani et al., 2008; Callan et al., 2007; Faber et al., 1997; Stanojevic´ et al., 2011). Especially important is the significantly higher content of carvone (85.9–89.3%), a bioactive component with an array of different biological activities (de Carvalho and da Fonseca, 2006; Bailer et al., 2001; Bakkali et al., 2008; Faber et al., 1997). The major components are believed to be mainly responsible for the biological activity of this particular essential oil (Bakkali et al., 2008; Bailer et al., 2001). The usage of carvone as a reversible suppressant of sprouting in stored potatoes or flower bulbs is probably its most important technical application (Bailer et al., 2001). Based on the results obtained in our investigation, the essential oil from dill seeds from Southeast Serbia (Svrljig) could be a potential natural source for the industrial production of carvone.
´ L.P., et al., The yield, composition and hydrodistillation kinetics of the Please cite this article in press as: Stanojevic, essential oil of dill seeds (Anethii fructus) obtained by different hydrodistillation techniques. Ind. Crops Prod. (2014), http://dx.doi.org/10.1016/j.indcrop.2014.10.067
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Table 8 The identified constituents of the dill seeds essential oil from four different hydrodistillation methodologies (I–IV). Rt/min
RI a
Component
IDc
Hydrodistillation technique I
II
III
IV
tr 2.1 tr tr tr tr tr tr tr tr tr 2.6 tr tr 2.5 tr 1.5 tr 2.3 88.8 tr tr tr tr tr tr tr tr tr 99.8
tr 0.9 tr tr 0.2 tr tr tr tr tr tr 2.8 tr tr 2.7 tr 1.6 tr 2.4 89.0 tr tr tr 0.3 tr tr tr tr tr 99.9
tr 1.4 tr tr 0.1 tr tr tr tr tr tr 2.7 tr tr 2.7 tr 1.4 tr 2.0 89.3 tr tr 0.1 0.2 tr tr tr tr tr 99.9
Content, % 5.821 5.923 5.923 7.243 7.399 7.997 8.263 8.351 8.361 9.616 9.826 9.897 9.923 9.923 10.072 10.383 10.409 10.736 10.761 11.134 11.346 11.704 11.865 12.127 12.183 13.938 17.967 20.252 23.087
1020 1024 1025 1089 1095 1119 1132 1133 1137 1184 1186 1191 1192 1193 1200 1212 1215 1226 1226 1239 1247 1266 1273 1282 1289 1356 1517 1620 1722
trb 5.1 tr tr tr tr tr tr tr tr tr 3.0 tr tr 2.7 tr 1.4 tr 1.8 85.9 tr tr tr tr tr tr tr tr tr 99.9
p-Cymene Limonene -Phellandrene p-Cymenene Linalool trans-p-Mentha-2,8-dien-1-ol cis-Limonene oxide cis-p-Mentha-2,8-dien-1-ol trans-Limonene oxide Dill ether ␣-Terpineol cis-Dihydro carvone Dihydro carveol neo-Dihydro carveol trans-Dihydro carvone iso-Dihydro carveol trans-Carveol neoiso-Dihydro carveol cis-Carveol Carvone p-Anis aldehyde Isopiperitenone trans-Carvone oxide trans-Anethole Thymol cis-Carvyl acetate Myristicin Dill apiole Neocnidilide (syn. Sedanolide) Total identified:
a,b,c a,b,c a,b,c a,b a,b,c a,b a,b a,b a,b a,b a,b,c a,b a,b a,b a,b a,b a,b a,b a,b,c a,b,c a,b,c a,b a,b a,b,c a,b,c a,b,c a,b,c a,b a,b
a
RI = Retention index. tr = trace amount (<0.05%). c ID = method of identification, a = compound identified by mass-spectra comparison, b = compound identity confirmed by retention index comparison with literature values, c = co-injection of a standard. b
3.5. Influence of the hydrodistillation techniques on the physicochemical properties of the dill oil Physicochemical characteristics the essential oils obtained in the four different methodologies of hydrodistillation are given in Table 9.
study of the yield, composition and hydrodistillation kinetics of the essential oil from dill seeds (Anethii fructus) obtained by four different techniques of Clevenger-type hydrodistillation (technique I–IV) was carried out. The obtained results showed that the essential oil yield, composition and hydrodistillation kinetics depend on the hydrodistillation technique used. The highest oil yield was obtained by hydrodistillation technique III (3.74 ml/100 g
Table 9 Physicochemical properties of essential oil from dill seeds obtained by four hydrodistillation techniques. Hydrodistillation technique
Relative density (d20 , g/ml)
Refractive index (nD 20 )
Optical rotation (◦ )
Solubility (volume parts of 90% ethanol per 1 ml of the essential oil)
Technique I Technique II Technique III Technique IV
0.899 0.896 0.902 0.897 0.895–0.910
1.487 1.484 1.489 1.485 1.481–1.492
+76 +74 +77 +75 +70 to +80
1.5 2 1.5 2 1 volume or more of 90% ethanol
a a
According to British Pharmacopoeia (2009).
The obtained pale-yellow essential oils had a pleasant typical dill seeds smell. The values of the relative density, refractive index and optical rotation for the oil differed only slightly from one technique to the other. The results agree fairly well with the literature data in the British Pharmacopoeia (2009). 4. Conclusion The goal of this study was envisaged to pinpoint the optimal hydrodistillation technique for the extraction of the essential oil of A. graveolens seeds. In order to achieve this goal a comparative
of dry plant material). Two hydrodistillation kinetics models of essential oil from dill seeds were described mathematically: model Ponomarev and non-stationary diffusion model. Quantitative composition of the resulting oils depended on the hydrodistillation technique used. The investigated oils, obtained by techniques I, II, III and IV contained carvone as the major constituent (85.9, 88.8, 89.0 and 89.3%, respectively). Besides carvone, limonene, cis-dihydrocarvone, trans-dihydrocarvone, cis-carveol and transcarveol, other oil components of dill seeds were identified in significantly lower amounts. Based on these results, an optimal hydrodistillation technique for the extraction of the essential oil
´ L.P., et al., The yield, composition and hydrodistillation kinetics of the Please cite this article in press as: Stanojevic, essential oil of dill seeds (Anethii fructus) obtained by different hydrodistillation techniques. Ind. Crops Prod. (2014), http://dx.doi.org/10.1016/j.indcrop.2014.10.067
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from dill seeds with maximal yield and high carvone content could be devised. The results also suggest that the dill seeds’ essential oil from Southeast Serbia could be regarded as a potential natural source of bioactive carvone. Acknowledgement This work was supported under the Project on Development of Technology number TR-34012 by the Ministry of Education, Science and Technological Development of the Republic of Serbia. References Bailer, J., Aichinger, T., Hackl, G., Hueber, K., Dachler, M., 2001. Essential oil content and composition in commercially available dill cultivars in comparison to caraway. Ind. Crops Prod. 14, 229–239. Bakkali, F., Averbeck, S., Averbeck, D., Idaomar, M., 2008. Biological effects of essential oils – a review. Food Chem. Toxicol. 46, 446–475. British Pharmacopoeia 2009. London: Crown Copyright, 2008. Callan, N.W., Johnson, D.L., Westcott, M.P., Welty, L.E., 2007. Herb and oil composition of dill (Anethum graveolens L.): effects of crop maturity and plant density. Ind. Crops Prod. 25, 282–287. de Carvalho, C.C.C.R., da Fonseca, M.M.R., 2006. Carvone: why and how should one bother to produce this terpene. Food Chem. 95, 413–422. Delaquis, P.J., Stanich, K., Girard, B., Mazza, G., 2002. Antimicrobial activity of individual and mixed fractions of dill, cilantro, coriander and eucalyptus essential oils. Int. J. Food Microbiol. 74, 101–109. Faber, B., Bangert, K., Mosandl, A., 1997. GC-IRMS and enantioselective analysis in biochemical studies in dill (Anethum graveolens L.). Flavour Fragr. J. 12, 305–314. Ghassemi-Golezani, K., Andalibi, B., Zehtab-Salmasi, S., Saba, J., 2008. Effects of water stress during vegetative and reproductive stages on seed yield and essential oil content of dill (Anethum graveolens L.). J. Food Agric. Environ. 6, 282–284. Hosseinnzadeh, H., Karimi, G.R., Ameri, M., 2002. Effects of Anethum graveolens L. seed extracts on experimental gastric irritation models in mice. BMC Pharmacol. 2, 1471–2210. Jirovetz, L., Buchbauer, G., Stoyanova, A.S., Georgiev, E.V., Damianova, S.T., 2003. Composition, quality control, and antimicrobial activity of the essential oil of long-time stored dill (Anethum graveolens L.) seeds from Bulgaria. J. Agric. Food Chem. 51, 3854–3857. Koppula, S., Choi, D.K., 2011. Anethum Graveolens Linn (Umbelliferae) extract attenuates stress-induced urinary biochemical changes and improves cognition in scopolamine induced amnesic rats. Trop. J. Pharm. Res. 10, 47–54. Leung, A.Y., Foster, S., 2003. Encyclopedia of common natural ingredients (used in food, drugs, and cosmetics), Second edition. A John Wiley & Sons Inc., Hoboken, New Jersey.
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´ L.P., et al., The yield, composition and hydrodistillation kinetics of the Please cite this article in press as: Stanojevic, essential oil of dill seeds (Anethii fructus) obtained by different hydrodistillation techniques. Ind. Crops Prod. (2014), http://dx.doi.org/10.1016/j.indcrop.2014.10.067