Fractionation of Bergamot and Lavandin Crude Essential Oils by

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Fractionation of Bergamot and Lavandin Crude Essential Oils by Solvent Extraction: Phase Equilibrium at 298.2 K Cristina C. Koshima,† Karina T. Nakamoto,† Keila K. Aracava,† Alessandra L. Oliveira,‡ and Christianne E. C. Rodrigues*,† †

Separation Engineering Laboratory (LES), Department of Food Engineering (ZEA-FZEA), and ‡Natural Products and High Pressure Technology Laboratory (LTAPPN), Department of Food Engineering (ZEA-FZEA), University of São Paulo (USP), P.O. Box 23, 13635-900 Pirassununga, SP Brazil ABSTRACT: Essential oils are primarily composed of terpenic hydrocarbons and oxygenated compounds, which impart the most pronounced flavors and the best sensory properties, whereas terpenic hydrocarbons tend to decompose when heated or exposed to air, resulting in a loss of sensorial quality. Liquid extraction technology using hydrous ethanol as a solvent can be employed to reduce the amount of terpenic hydrocarbons (deterpenation) in essential oils, thereby improving their quality and shelf life. In this paper, liquid− liquid equilibrium data that have not previously been published concerning systems composed of bergamot and lavandin crude essential oils and hydroalcoholic solvents at 298.2 K are presented. It was observed that an increase in the water content in the solvent leads to a decrease in the extraction of compounds and to an enhancement in the selectivity of the solvent. The bergamot oil exhibited a lower system solubility compared with lavandin oil systems. The experimental equilibrium data were compared to the phase compositions calculated using NRTL and UNIQUAC interaction parameters, which were previously adjusted by Chiyoda et al.1 [J. Chem. Eng. Data 2011, 56, 2362−2370], and the best phase composition description was associated with the bergamot crude essential oil. compose when heated or exposed to air, resulting in off flavors that may contribute to a loss in oil quality.6 In this context, the industrial practice known as deterpenation aims to concentrate the oxygenated compounds by reducing the amount of terpenic hydrocarbons present in the essential oil.7 As a result of this process, two fractions are produced: one rich in terpenic hydrocarbons and the other rich in oxygenated compounds. The extracts containing larger quantities of oxygenated compounds exhibit higher stability, flavoring power and greater solubility in polar media, and consequently, they have the greatest commercial value compared to crude oil.8,9 To improve the quality of volatile oils, many methodologies have been investigated and proposed in the literature to deterpenate essential oils.9 Methods that use heating, such as distillation, could make the essential oil more susceptible to degradation.10 Supercritical fluid extraction and membrane processing exhibit high economic costs related to the deployment and maintenance of the operating line11 and difficulties in the adequacy of the material that comprises the membrane, respectively.12 Although liquid−liquid extraction usually requires a subsequent desolventization step, this methodology appears to be very

1. INTRODUCTION Essential oils are oily liquid mixtures that have high volatility and flavoring properties. These natural products are obtained from different parts of vegetable material, such as leaves, seeds, roots, and fruits.2 With respect to their chemical compositions, essential oils are primarily composed of terpenic hydrocarbons and oxygenated compounds. 3,7-Dimethyl-1,6-octadien-3-ol also known as linalool and 3,7-dimethylocta-1,6-dien-3-yl acetate also known as linalyl acetate are the major oxygenated components of bergamot and lavandin essential oils. Linalool is generally applied in nonfood products, such as soaps, detergents, shampoos, lotions, and perfumes, whereas linalyl acetate has great demand as a food additive due to its unique flavor.3,4 The terpenic hydrocarbon 1-methyl-4-(1-methylethenyl)cyclohexene, also known as limonene, one of the main representatives of this class of compounds, can be found in bergamot and lavandin essential oils and shows uses as a flavoring agent in foods, medicines, and cleaning products. Limonene can also be used as a solvent for removing oil from machine parts.3 Although all volatile compounds possess some aromatic properties, the fragrance of essential oils is primarily due to the oxygenated components because they commonly present the best sensory characteristics, and therefore, they are the most required by industries.5 Terpenic hydrocarbons tend to de© XXXX American Chemical Society

Received: June 24, 2014 Accepted: December 4, 2014

A

dx.doi.org/10.1021/je500581h | J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

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and ions source was set at 518.2 K; the ion source temperature was set at 473.2 K; and an injection volume of 1.0 μL. The acquisition of mass spectra was performed over the mass range of (40 to 800) m/z. Electron impact ionization was used at 70 eV (EI). Identification of the mass spectra was performed based on their similarities using the CG-MS solutions version 2.5 software, which is based on the NIST 08 and NIST 08s libraries. With the objective of obtaining an accurate and reliable identification of the components, the terpenic hydrocarbons and oxygenated compounds present in the oils were also identified through comparison with the retention times of pure analytical standards (mass-fraction purity greater than 0.97) that were injected using the same chromatography conditions. The Kovats index (KI) defined according to eq 1, dimensionless, can also aid in the identification of compounds present in the oil samples. The same compound analyzed in two or more similar experimental conditions usually has similar KI values.15

appropriate for the deterpenation of essential oils because it can be conducted at room temperature and atmospheric pressure, therefore requiring less energy resources than practices such as distillation and supercritical fluid extraction.5 In fact, the use of milder operating conditions is necessary to preserve the sensory properties of the oils.13 Moreover, the utilization of alcoholic solutions composed of ethanol and water as the solvent for the liquid extraction may exhibit, depending on the application, the advantage of not requiring the desolventization step. Essential oil alcoholic extracts are in high industrial demand as flavoring ingredients for drinks and perfumes because of their high solubility in aqueous solutions. In addition, these extracts are highly aromatic and possess great stability because oxidation reactions are reduced in the presence of ethanol.14 The study of phase equilibria provides essential information for the proper design and optimization of separation processes. However, there are scarce, or even a lack of, data in the literature on the liquid−liquid equilibrium for systems containing crude essential oils and solvents. Based on the aforementioned considerations, in this study, liquid−liquid equilibrium data for systems composed of bergamot (Citrus aurantium bergamia) and lavandin (Lavandula hibrida) crude essential oils and hydroalcoholic solutions were obtained at 298.2 K. NRTL and UNIQUAC binary interaction parameters, which were previously adjusted by Chiyoda et al.1 for model systems composed of limonene, linalyl acetate, linalool and hydrous ethanol, were used to calculate the phase compositions of these real systems. In addition to the genuine contribution of this work as being the first to determine the phase equilibrium data for systems containing crude essential oils, it was also possible to observe the predictive ability of the thermodynamic equations interaction parameters for providing the phase compositions, and these equations are useful in the simulation of extractors devoted to the deterpenation of essential oils.

⎡ log RT(x) − log RT(P ) ⎤ z ⎥ KI(x) = 100Pz + 100⎢ ⎣ log RT(Pz + 1) − log RT(Pz) ⎦

(1)

where Pz is the carbon number of the alkane immediately preceding the analyte; RT(x) is the analyte retention time, RT(Pz) is the retention time of the alkane immediately preceding the analyte, and RT(Pz+1) is the retention time of the alkane immediately following the analyte. All retention times are expressed in time units. The alkane retention times (RT(P)), were determined using a standard mixture of a homologous series of n-alkanes (C10−C40) (Sigma-Aldrich, USA) that provided the Kovats index under the same chromatographic conditions used in the analysis of the compounds in the oil samples. To quantify each compound identified by GC-MS, a gaschromatograph with a flame ionization detector (GC-FID) system (Shimadzu, model GC 2010 AF, Japan) equipped with an automatic injector (Shimadzu, model AOC 20i, Japan) was used under the following experimental conditions: DB-FFAP capillary (nitroterephthalic acid-modified polyethylene glycol) column (Agilent, USA), 0.25 μm, 30 m × 0.25 mm i.d.; helium as the carrier gas at a flow rate of 1.13 mL·min−1; injection temperature of 523.2 K; column temperature range of (373.2 to 513.2) K with a heating rate of 8 K·min−1; detection temperature of 553.2 K; and an injection volume of 1.0 μL. The quantification was performed using the internal normalization procedure without corrections for the response factor. The essential oil compositions were expressed in terms of the main compounds, in others words, those that presented mass percentages of greater than 0.10 %. 2.3. Experimental Determination of Liquid−Liquid Equilibrium Data. Different masses of crude oil and solvent were weighed on an analytical balance with a readability of 0.0001 g (Adam, model PW 254, USA) directly into polypropylene centrifuge tubes (Corning, USA) with capacities of (15 or 50) mL to obtain different mass ratios of solvent to oil (1/1, 1.5/1, 2/1, and 3/1), and consequently, different tie lines were obtained. The tubes were vigorously stirred at 2800 rpm for at least 10 min at room temperature (approximately 298 K), centrifuged for 20 min at 5000 × g at 298.2 ± 1.5 K in a centrifuge equipped with a temperature controller (Thermo Electron, model CR3i, France) and then placed in a thermostatic bath at 298.2 ± 0.1 K for 24 h (Marconi, model MA-184, Brazil).

2. MATERIALS AND METHODS 2.1. Materials. Binary solutions composed of ethanol and water were employed as solvents and prepared by the addition of deionized water (Millipore, Milli-Q, Bedford, MA, USA) in absolute ethanol (Merck, Germany) with a mass-fraction purity greater than 0.998. For the systems containing bergamot essential oil, hydroalcoholic solvents with water mass fractions of 0.3217 ± 0.0076, 0.3944 ± 0.0089, 0.5066 ± 0.0168, and 0.6169 ± 0.0250 were used. Regarding lavandin essential oil, the following water mass fractions in the solvents were used: 0.3559 ± 0.0097, 0.4333 ± 0.0149, and 0.4960 ± 0.0107. The crude bergamot (Citrus aurantium bergamia) and lavandin essential oils (Lavandula hibrida) were purchased from Ferquima (Brazil). 2.2. Identification and Quantification of Compounds Present in Crude Essential Oils. The components present in the bergamot and lavandin crude essential oils were first identified using gas chromatography coupled to mass spectrometry (GC-MS). A CG-MS (Shimadzu, model QP 2010 Plus, Japan) equipped with an automatic injector (Shimadzu, model AOC-5000, Japan) was used under the following experimental conditions: DB-FFAP capillary (nitroterephthalic acid-modified polyethylene glycol) column (Agilent, USA), 0.25 μm, 30 m × 0.25 mm i.d.; helium as the carrier gas at a flow rate of 1.56 mL·min−1; split ratio of 1:50; injection temperature of 523.2 K; column temperature range of (373.2 to 513.2) K with a heating rate of 8 K·min−1; temperature of interface of column B



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After this treatment, the two phases became clear with a welldefined interface. Samples from the top (TP, terpene-rich) and bottom (SP, solvent-rich) phases were collected separately using syringes, and the compositions of both phases were measured. The contents of the essential oil compounds and ethanol were determined by gas chromatography GC-FID (Shimadzu, model GC 2010 AF, Japan) using the same experimental conditions previously described. The components were quantified using the external standard method. The water content was determined by Karl Fischer titration (Metrohm, 787 KF Titrino, Switzerland) using Karl Fischer reagents purchased from Merck (Germany). In this study, the tie lines were obtained at least in duplicate, and all measurements were performed at least in triplicate and the standard uncertainties were Type A according to Taylor and Kuyatt.16 With the purpose of determining the mass balances, the procedure developed by Marcilla et al.17 was adopted in terms of average global mass balance deviations (δ). This procedure for evaluating the quality of liquid−liquid experimental data was used in previous works in which essential oil compounds were present.1,8,9,18 2.4. Phase Composition Calculation Procedure at Equilibrium Condition. The experimental liquid−liquid equilibrium data obtained for the systems containing bergamot and lavandin crude essential oils were compared to compositions calculated using NRTL and UNIQUAC parameters previously adjusted by Chiyoda et al.1 for a model bergamot essential oil system composed of limonene (1), linalyl acetate (2), linalool (3), ethanol (4), and water (5) at 298.2 ± 0.1 K. In the calculation procedure, the compositions of the terpene and solvent phases were obtained by performing flash calculations based on the overall experimental composition of the mixtures using an objective function of compositions according to Stragevitch and d’Avila.19 The deviations between the experimental and calculated compositions in both phases were calculated according to eq 2, as dimensionless figures:

Table 1. Chemical Composition of Bergamot Crude Essential Oil

+

−

⎭

KIb

IDc

%

limonene γ-terpinene p-cimene linalool oxide linalool linalyl acetate α-bergamotene β-Caryophilene neral α-Terpineol β-bisabolene + neril acetate geranial geranil acetate nerol

2.80 3.01 3.17 3.23 5.30 5.50 5.84 6.09 7.04 7.12 7.47 7.63 7.80 8.23

1602 1616 1626 1630 1839 1849 1864 1875 2016 2020 2037 2045 2053 2072

standard standard standard NIST-MS standard standard NIST-MS standard standard standard NIST-MS standard NIST-MS NIST-MS

37.07 3.81 0.41 0.19 29.22 27.09 0.28 0.41 0.11 0.10 0.73 0.20 0.24 0.14

Table 2. Chemical Composition of Crude Lavandin Essential Oil compound β-pinene limonene eucaliptol β-ocimene carene propanoic acid octenil acetate butanoic acid 3-octenol canfor linalool linalyl acetate santalene α-bergamotene β-caryophilene* + terpinen-4ol* + lavandulol acetate β-farnesene lavandulol terpineol borneol germacrene β-bisabolene neril acetate nerol geraniol bisabolol

⎫1/2

⎪ wiSP,calcd )2 ]) /2NK ⎬ ,n ⎪

RTa/min

a Retention time. bKovatz index, dimensionless. cCompound identification type.

⎧ ⎛ N K ⎪ ⎜ ∑ ∑ [(wiTP,exptl )2 Δw = ⎨ − wiTP,calcd ,n ,n ⎪⎜ ⎝ ⎩ n=1 i=1 (wiSP,exptl ,n

compound

(2)

where N represents the total number of tie lines, K represents the total number of components, w represents the mass fraction, the subscripts i and n represent the component and tie line, respectively, and the superscripts TP and SP represent the terpene and solvent phases, respectively. The superscripts exptl and calcd refer to the experimental and calculated compositions.

RTa /min

KIb

2.47 2.79 2.86 2.96 3.22 3.50 3.74 4.07 4.28 4.90 5.28 5.48 5.71 5.82 6.04

1541 1600 1603 1613 1630 1647 1660 1677 1688 1819 1838 1848 1858 1863 1872

6.65 6.79 7.10 7.19 7.36 7.65 7.78 8.30 8.86 13.32

1898 2004 2020 2024 2032 2046 2052 2075 2098 2618

IDc standard standard standard NIST-MS NIST-MS NIST-MS NIST-MS NIST-MS NIST-MS NIST-MS standard standard NIST-MS NIST-MS standard*/ NIST-MS NIST-MS NIST-MS standard NIST-MS NIST-MS NIST-MS NIST-MS NIST-MS standard NIST-MS

% 0.55 0.70 8.52 1.97 0.22 0.30 0.48 0.27 0.51 0.11 43.57 28.36 0.38 0.24 6.08 0.78 0.85 1.05 2.57 0.85 0.21 0.69 0.19 0.41 0.14

a Retention time. bKovatz index, dimensionless. cCompound identification type.

3. RESULTS AND DISCUSSION 3.1. Bergamot and Lavandin Crude Essential Oil Characterization. The normalized compositions of the bergamot and lavandin crude essential oils are presented in Tables 1 and 2, respectively. As previously mentioned, the compounds were identified by GC-MS (through comparison with the retention times of pure compounds, mass spectra similarity and Kovats Indices comparison) and quantified by GC-FID. The KIs were calculated using eq 1. However, the use of the KI values to identify the essential oil compounds was not possible

because there were no data in the literature regarding the same column phase used in this study or even other columns with polar phases, making the comparison impossible. On the other hand, the KI values presented in this paper can contribute to expanding the available database to provide an identification tool for this type of compound. The compositions of the bergamot and lavandin crude essential oils obtained in this work are in qualitative agreement, C



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identified by the markers located in the left, center and right of the phase diagrams, respectively. As shown in Figures 1 and 2, in both systems, the increase in the hydration of ethanol is responsible for expanding the twophase coexistence region. The addition of water most likely changes the solvent polarity, making it less soluble in the essential oil and therefore expanding the biphasic region. In this context, the methodology suggested by Langhals24 and cited by Reichardt25 was used to calculate the polarity indices of the solvents used in this work with the aim to exemplify, in numbers, how the addition of water to the ethanol can change the solvent polarity. The polarity indices ET(30)solv, solvexpressed in kcal/mol, and normalized polarity indices ENT , dimensionless, were calculated according to eqs 3 and 4, respectively, for all ethanol/water mixtures studied as solvents.24,25

with respect to the determined compounds, with some studies reported in the literature.20−23 3.2. Study of Phase Equilibria. Although many compounds are present in the crude essential oils (see Tables 1 and 2), to conduct the liquid−liquid equilibrium experiments, the compositions of the phases and the compositions of the crude oils were expressed only in terms of the components of interest. For bergamot crude oil, the composition was expressed only in terms of the major compounds, which are limonene, linalool and linalyl acetate, neglecting all other terpene hydrocarbons and oxygenated compounds. These three compounds together comprise more than 93 % of the essential oil, as shown in Table 1. Therefore, the composition of the bergamot oil used in this study, normalized in terms of only the major components, was 39.69 % limonene, 31.29 % linalool, and 29.02 % linalyl acetate. With respect to the major compounds of the lavandin crude oil, linalool and linalyl acetate are responsible for approximately 72 % of the oil (Table 2). As shown in Table 2, the amount of limonene present in this oil is too small (0.70 %), being this value in accordance with values reported by Andogan et al.22 and Rojo et al.23 In both aforementioned studies, values equal to 0.90 % for limonene composition in the lavandin crude oils were reported. Consequently, the strategy adopted to minimize the possible experimental errors associated with the low limonene level was to sum the compositions of all the terpenic hydrocarbons. Therefore, the compositions of the following compounds were added to the limonene: β-pinene, β-ocimene, carene, santalene, α-bergamotene, β-caryophyllene, β-farnesene, germacrene, and β-bisabolene. In this case, the composition of lavandin oil, normalized in terms of linalool, linalyl acetate, and terpenic hydrocarbons, was (55.44, 34.73, and 9.83) %, respectively. In short, the experimental liquid−liquid systems containing bergamot crude essential oil were composed of limonene (1) + linalyl acetate (2) + linalool (3) + ethanol (4) + water (5) and were obtained at 298.2 ± 0.1 K. Similarly, the systems with lavandin crude essential oil were composed of terpenic hydrocarbons (1) + linalyl acetate (2) + linalool (3) + ethanol (4) + water (5), and they were obtained at the same temperature as the bergamot data. The overall phase compositions and the corresponding tie lines for the systems containing crude essential oils are shown in Tables 3 (bergamot oil) and 4 (lavandin oil). The information on the maximum Type A standard uncertainties is also presented in these tables. The average global mass balance deviations (δ), calculated using the procedure developed by Marcilla et al.,17 for each phase diagram measured in the present work varied within the range of (0.02 to 2.33) % and (0.02 to 3.13) % for the systems containing bergamot and lavandin crude essential oils, respectively. The small deviations in the mass balances and the low experimental data uncertainties (Tables 3 and 4) confirm the good quality of the measured experimental data. The tie lines obtained using a solvent to oil mass ratio of 1 for the bergamot and lavandin crude oil systems are presented in Figures 1 and 2, respectively. In these phase diagrams, the ordinate axis presents the mass fractions of linalool (w3) while the abscissa axis refers to the mass fractions of the mixed solvent, hydrous ethanol (w4+w5). Therefore, for each ethanol hydration level studied, the composition of the terpene phase, overall composition and solvent phase, in terms of the mass fractions of linalool (3) and solvent [ethanol (4) + water (5)], can be

E T(30)solv = E D ln(c p/c* + 1) + E T(30)0

(3)

where cp is the molar concentration of the more polar component, mol/L; ET(30)0 is the ET(30) value of the pure component with lower polarity, kcal/mol; ED and c* are specific parameters for the binary solvent under study, kcal·mol−1 and mol·L−1, respectively. According to Langhals24 for the binary mixtures composed by ethanol and water the ED and c* values are 2.04 kcal·mol−1 and 5.47 mol·L−1, respectively. The value of ET(30)0 related to the ethanol was taken from Reichardt25 and it is 51.90 kcal·mol−1. E TN

solv

=

E T(30)solv − 30.7 32.4

(4)

In possession of the aforementioned values, the polarity indices and normalized polarity indices were calculated according to eqs 3 and 4 and are shown in Tables 3 and 4. It can be observed that the polarity index increases as the value of water mass fraction in the solvent increases. According to solv Reichardt,25 the corresponding ENT scale ranges from 0.000 for tetramethylsilane, the least polar solvent, solv to 1.000 for water, the most polar solvent. For example, an ENT value of 0.738 for ethanol with 0.3217 mass fraction of water means that this solvent exhibits 73.8 % of the solvent polarity of water. In fact, the changes in solvent polarity and, consequently, increase in the biphasic region are very interesting for the essential oil fractionation process by liquid extraction because the largest regions of two-phase coexistence render a more flexible procedure. In other words, a larger number of different mixtures could be fractionated, which is very useful in the case of essential oils that can exhibit variations in their compositions due to the seasonality, part of plant from which the oil was obtained, and so on. Another aspect that should be considered in the development of a new approach for the deterpenation of essential oils by liquid extraction is the distribution coefficient (k), dimensionless, mathematically expressed by eq 5. ki =

wiSP wiTP

(5)

Through this calculation procedure, the migration of oxygenated compounds and terpenic hydrocarbons can be measured. The deterpenation process is technically feasible only if different distribution coefficients are obtained for these two classes of components. D


E

0.1452 0.1248 0.1068 0.0728 0.1451 0.1164 0.0986 0.0724 0.1453 0.1165 0.0977 0.0736 0.1435 0.1161 0.0993 0.0728

0.1565 0.1400 0.1197 0.0785 0.1564 0.1255 0.1063 0.0781 0.1567 0.1256 0.1053 0.0793 0.1548 0.1252 0.1070 0.0785

w3 0.3390 0.4065 0.4457 0.4938 0.3028 0.3627 0.3998 0.4500 0.2521 0.2953 0.3273 0.3683 0.1936 0.2298 0.2521 0.2871

w4

overall composition (OC) w2 0.1607 0.1927 0.2114 0.2553 0.1972 0.2362 0.2604 0.3004 0.2471 0.3032 0.3360 0.3781 0.3118 0.3701 0.4058 0.4620

w5 0.2660 0.2744 0.3000 0.3517 0.2881 0.2895 0.2997 0.3371 0.3103 0.3087 0.3094 0.3213 0.3363 0.3305 0.3287 0.3333

w1 0.1962 0.1764 0.1615 0.1539 0.2206 0.2047 0.1934 0.1729 0.2460 0.2322 0.2254 0.2120 0.2685 0.2657 0.2604 0.2525

w3

w4 0.2690 0.2821 0.2748 0.2323 0.2171 0.2371 0.2367 0.2217 0.1666 0.1871 0.1898 0.1903 0.1112 0.1187 0.1281 0.1330

terpene phase (TP) 0.2007 0.1984 0.2009 0.2172 0.2217 0.2182 0.2200 0.2243 0.2417 0.2344 0.2352 0.2371 0.2602 0.2601 0.2576 0.2555

w2 0.0681 0.0687 0.0628 0.0449 0.0525 0.0505 0.0502 0.0440 0.0354 0.0376 0.0402 0.0393 0.0238 0.0250 0.0252 0.0257

w5 0.0192 0.0393 0.0487 0.0272 0.0045 0.0100 0.0136 0.0153 0.0007 0.0014 0.0020 0.0031 0.0001 0.0001 0.0001 0.0002

w1 0.0582 0.0765 0.0777 0.0534 0.0264 0.0414 0.0450 0.0433 0.0109 0.0155 0.0179 0.0202 0.0035 0.0041 0.0047 0.0059

w3

w4 0.5006 0.5232 0.5329 0.5370 0.4475 0.5128 0.5199 0.5248 0.3807 0.4233 0.4274 0.4412 0.3316 0.3258 0.3305 0.3696

solvent phase (SP) 0.0299 0.0493 0.0554 0.0352 0.0097 0.0185 0.0225 0.0240 0.0026 0.0044 0.0056 0.0071 0.0004 0.0006 0.0007 0.0010

w2

w5 0.3921 0.3117 0.2853 0.3472 0.5119 0.4173 0.3990 0.3926 0.6051 0.5554 0.5471 0.5284 0.6644 0.6694 0.6640 0.6233

0.37 0.21 0.42 1.97 0.59 0.67 0.72 0.62 0.22 0.36 0.58 0.52 0.36 0.14 0.08 0.08

δ (%)

solv

Standard uncertainties u are u(w) ≤ 0.0398, u(T) = 0.05 K, and u(p) = 10 kPa. bw5S = water mass fraction in the solvent. cPolarity index ET(30)solv, kcal/mol, calculated according to eq 3. dNormalized

0.6169 (55.83) (0.776)

0.5066 (55.44) (0.764)

0.1986 0.1360 0.1164 0.0996 0.1985 0.1592 0.1349 0.0991 0.1988 0.1594 0.1337 0.1007 0.1963 0.1588 0.1358 0.0996

w1

polarity index ENT , dimensionless, calculated according to eq 4.

a

1/1 1.5/1 2/1 3/1 1/1 1.5/1 2/1 3/1 1/1 1.5/1 2/1 3/1 1/1 1.5/1 2/1 3/1

0.3217 (54.60) (0.738)

0.3944 (54.99) (0.750)

solvent/oil ratio

(ENT )d

solv

(ET(30)solv)c

w5Sb

Table 3. Liquid−Liquid Equilibrium Data for Bergamot Crude Essential Oil Systems Composed by Limonene (1) + Linalyl Acetate (2) + Linalool (3) + Ethanol (4) + Water (5), at T = 298.2 K and Pressure p = 0.1 MPaa

Journal of Chemical & Engineering Data Article



F

a

0.4960 (55.40) (0.762)

solv

polarity index ENT , dimensionless, calculated according to eq 4.

1.70 2.57 3.13 1.26 1.79 1.53 1.00 0.07 0.27 0.33 0.22

Standard uncertainties u are u(w) ≤ 0.0507, u(T) = 0.05 K, and u(p) = 10 kPa. bw5S= water mass fraction in the solvent. cPolarity index ET(30)solv, kcal/mol, calculated according to eq 3. dNormalized

w5

0.6007 0.5450 0.4276 0.5822 0.5330 0.4902 0.4027 0.6193 0.6003 0.6008 0.5521 0.3841 0.4182 0.4627 0.3960 0.4282 0.4482 0.4703 0.3718 0.3839 0.3786 0.4171

w4 w3

0.0127 0.0279 0.0725 0.0165 0.0288 0.0432 0.0785 0.0074 0.0125 0.0154 0.0216 0.0023 0.0082 0.0329 0.0049 0.0092 0.0168 0.0432 0.0014 0.0031 0.0048 0.0085 0.0002 0.0007 0.0043 0.0004 0.0008 0.0016 0.0053 0.0001 0.0002 0.0004 0.0007 0.0740 0.1094 0.1833 0.0934 0.1135 0.1360 0.1795 0.0626 0.0839 0.0956 0.1173 0.2860 0.3514 0.4176 0.3121 0.3497 0.3783 0.4176 0.2485 0.2887 0.3120 0.3455 0.3579 0.3009 0.2222 0.3172 0.2907 0.2598 0.2075 0.3639 0.3324 0.3107 0.2749 0.2270 0.1924 0.1431 0.2205 0.1974 0.1806 0.1558 0.2502 0.2318 0.2217 0.2076 0.0551 0.0459 0.0338 0.0568 0.0487 0.0453 0.0396 0.0748 0.0632 0.0600 0.0547 0.1425 0.1768 0.2135 0.2324 0.2668 0.2932 0.3330 0.2574 0.3083 0.3388 0.3850 0.2572 0.3227 0.3864 0.2906 0.3337 0.3667 0.4165 0.2435 0.2915 0.3204 0.3641 0.3374 0.2813 0.2249 0.2609 0.2215 0.1886 0.1389 0.2729 0.2189 0.1864 0.1372 0.2032 0.1694 0.1354 0.1698 0.1387 0.1181 0.087 0.1777 0.1424 0.1213 0.0893 2/1 1/1 1.5/1 1/1 1.5/1 2/1 3/1 1/1 1.5/1 2/1 3/1 0.3559 (54.81) (0.744) 0.4333 (55.18) (0.756)

0.0597 0.0498 0.0398 0.0463 0.0393 0.0334 0.0246 0.0485 0.0389 0.0331 0.0244

solvent phase (SP)

w2 w1 w5 w4 w3

terpene phase (TP)

w2 w1 w5 w4 w3

overall composition (OC)

w2 w1 solvent/oil ratio solv

(ENT )d

(ET(30)solv)c

w5Sb

Table 4. Liquid−Liquid Equilibrium Data for Lavandin Crude Essential Oil Systems Composed by Terpenic Hydrocarbons (1) + Linalyl Acetate (2) + Linalool (3) + Ethanol (4) + Water (5), at T = 298.2 K and Pressure p = 0.1 MPaa

Figure 3 shows the distribution coefficients for the essential oil components [limonene or terpenic hydrocarbons (1), linalyl acetate (2) and linalool (3)] present in the bergamot and lavandin crude oil systems, in the ordinate axis, as a function of the solvent to oil mass ratio, in the abscissa axis. These experimental data were determined at 298.2 ± 0.1 K using a water mass fraction in the solvent next to 0.5. As shown in Figure 3, for both systems, linalool (k3) exhibited the highest k value, followed by linalyl acetate (k2) and limonene or terpenic hydrocarbons (k1). Therefore, as expected, the oxygenated compounds are more soluble in hydrous ethanol than the terpenic hydrocarbons because these latter components do not possess a polar region in their molecular structures. The different k values obtained can enable the deterpenation of crude essential oils by liquid extraction using ethanol and water as the solvent. As shown in Figure 3, the largest extraction of the essential oil compounds is associated with an increase in the solvent to oil mass ratio, most likely due to the highest amount of solvent present in the system, which might provide a greater extraction of compounds. Additionally, by comparing the oils used in this study for two very similar values of water mass fraction in ethanol (Figure 3), it can be inferred that the fractionation appears to be more efficient for the bergamot oil systems once the oxygenated compounds migrate in a more expressive way to the solvent phase, as can be noted by the greatest k values compared to the lavandin oil systems. This behavior may be associated with the linalool content in the crude oil; according to Tables 1 and 2, the linalool content in the lavandin essential oil is almost double compared to the linalool content in the bergamot essential oil. Figure 4 presents the distribution of linalool between the phases for the system containing limonene, linalyl acetate, linalool, ethanol, and water (experimental data available in Chiyoda et al.1). The linalool mass fractions in the solvent phase are represented in the ordinate axis while the linalool mass fractions in the terpene phase are shown in the abscissa axis. In this figure, the experimental data from Chiyoda et al.1 were obtained using solvent to oil mass ratio of 1 and a solvent with a water mass fraction of 0.4215. This figure also presents experimental data concerning real systems composed of bergamot and lavandin crude essential oils. In this case, the data correspond to tie lines in which the solvent to oil mass ratios are 1 and in which the levels of water in the solvent are 0.3944 and 0.4333 for bergamot and lavandin oil systems, respectively. With respect to the data from Chiyoda et al.,1 it can be observed that for linalool mass fractions in the terpene phase of up to approximately 0.15, an increase in these compositions cause a significant increase in the level of linalool in the solvent phase. On the other hand, note that changes in values of the linalool mass fractions in the terpene phase above 0.15 do not appear to result in considerable increases in the linalool composition in the solvent-rich phase. This behavior results in a reduced distribution coefficient of linalool with increasing concentration of this component in the system. Regarding systems composed of crude essential oils, note that the values of the compositions of linalool in the terpene phases are greater than 0.15 in mass fraction. Although the compositions of the terpene phases in terms of linalool are different than the crude essential oils, the compositions of the solvent phases are very similar, independent of the initial linalool content in the oil.

δ (%)

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Figure 1. Tie lines obtained using a solvent/oil mass ratio = 1 for the systems containing bergamot crude essential oil composed by limonene (1) + linalyl acetate + (2) + linalool (3) + ethanol (4) + water (5), at 298.2 ± 0.1 K: (▲) terpene phase, (○) overall composition, (■) solvent phase. (a) Ethanol with 0.3217 of water mass fraction; (b) ethanol with 0.3944 of water mass fraction; (c) ethanol with 0.5066 of water mass fraction; (d) ethanol with 0.6169 of water mass fraction.

Figure 2. Tie lines obtained using a solvent/oil mass ratio = 1 for the systems containing lavandin crude essential oil composed by terpenic hydrocarbons (1) + linalyl acetate + (2) + linalool (3) + ethanol (4) + water (5), at 298.2 ± 0.1 K: (▲) terpene phase, (○) overall composition, (■) solvent phase. (a) Ethanol with 0.3559 of water mass fraction; (b) ethanol with 0.4333 of water mass fraction; (c) ethanol with 0.4960 of water mass fraction.

binary interaction parameters that were previously adjusted by Chiyoda et al.1 for model bergamot essential oil systems composed of limonene (1) + linalyl acetate (2) + linalool (3) + ethanol (4) + water (5). In fact, this practice enables us to verify the predictive capability of the parameters adjusted to the model systems in calculating the compositions of more complex systems, referred to as real systems. Concerning the lavandin crude essential oil, as previously mentioned, all of terpenic hydrocarbon compositions were summed and considered in the experimental study. In this case, to enable the use of the interaction parameters reported by

This behavior suggests that the major values of distribution coefficients obtained for bergamot oil (Figure 3) are in fact associated with the lower initial content of linalool present in this oil. Therefore, it could be hypothesized that the efficiency of the fractionation process is dependent on the initial linalool composition in the crude essential oil. 3.3. Phase Composition Calculation at Equilibrium Condition. As previously mentioned in section 2.4, the experimental compositions determined for the real systems containing bergamot or lavandin crude oils and hydrous ethanol at 298.2 ± 0.1 K were described using NRTL and UNIQUAC G



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The performance of the NRTL and UNIQUAC thermodynamic models in the description of phase compositions can be observed in Figures 5 and 6. In these figures, the mass fractions of essential oil compounds (w1 + w2 + w3) in the solvent phase and the mass fractions of solvent (w4 + w5) in the terpene phase are shown as functions of the solvent/oil mass ratio. The deviations between the experimental and calculated compositions that were obtained via eq 2 are presented in Table 5. As shown in Figures 5 and 6, the compositions of oil compounds solubilized in the solvent-rich phase were successfully described by both thermodynamic models. Regarding the solvent mass fractions in the terpene-rich phase, it is possible to observe a major difficultly in describing or even an inability to calculate the compositions associated with lavandin oil systems (Figure 6). It is important to note in Figure 6a and Table 5 the absence of the calculated compositions and deviation values, respectively, for the system containing crude lavandin essential oil and solvent with a water mass fraction of 0.3559. In fact, neither the NRTL model nor the UNIQUAC model was able to describe the phase compositions for this system. Therefore, the equilibrium compositions obtained using solvent to oil mass ratios of 1/1 and 1/1.5 and solvent with a water mass fraction of 0.4333 were not calculated using the UNIQUAC model (Figure 6b). With respect to systems composed of crude bergamot essential oil, the compositions of the entire experimental data set were described using the NRTL and UNIQUAC models. Additionally, in Figures 5 and 6, it can be observed that the largest water mass fraction studied or the lowest phase solubility shows the best results regarding the model description. As previously mentioned, the phase solubilities of the bergamot (Figure 5) and lavandin (Figure 6) crude oil systems were measured by quantifying the level of solvent (w4 + w5) in the oil or terpene-rich phase (TP) and the essential oil content (w1 + w2 + w3) in the solvent-rich phase (SP). To design and optimize the diverse types of products that can be derived from deterpenation processes, the solubility study enables the migration of compounds to be adjusted using different water mass fractions in ethanol. For both systems shown in Figures 5 and 6, it can be verified that the increase in the water mass fraction in the solvent promotes a decrease in phase solubility. In fact, ethanol and essential oil compounds are completely miscible, and the addition of water is a fundamental step to ensure the formation of two liquid phases, allowing the extraction process. The presence of water could promote an increase in the solvent polarity, causing a possible decrease in the mutual solubility of the components.1 It can also be observed in Figures 5 and 6 that the phase solubility tends to increase with higher solvent/oil mass ratio values because larger amounts of solvent might promote the maximization of the extraction of the components. During the acquisition of the experimental equilibrium data, it was possible to verify the high solubility of the lavandin oilcontaining systems, especially for the solvent with a water mass fraction of 0.3559 (Figure 6a). In the systems containing lavandin crude oil, the maximum oxygenated compound (linalool + linalyl acetate) mass fraction studied in the overall composition was 0.5402. In the bergamot oil systems, this maximum value was 0.3015. Chiyoda et al.1 used a maximum value of 0.3165 for the mass fraction of linalool plus linalyl acetate in their study, which allowed for the adjustment of

Figure 3. Distribution coefficients of limonene or terpenic hydrocarbons (k1), linalyl acetate (k2), and linalool (k3), at 298.2 ± 0.1 K, for the systems containing: (a) bergamot crude oil and ethanol with 0.5066 of water mass fraction and (b) lavandin crude oil and ethanol with 0.4960 of water mass fraction. Experimental: ■, k1; ○, k2;▲, k3.

Figure 4. Distribution diagram for the experimental data obtained by Chiyoda et al.1 to the bergamot oil model systems composed by limonene (1) + linalyl acetate + (2) + linalool (3) + ethanol (4) + water (5) (0.4215 of water mass fraction in the solvent) at 298.2 ± 0.1 K: (■) bergamot oil model system with solvent/oil mass ratio =1; (□) bergamot crude oil with solvent/oil mass ratio =1 and ethanol with 0.3944 of water mass fraction; (○) lavandin crude oil with solvent/oil mass ratio =1 and ethanol with 0.4333 of water mass fraction.

Chiyoda et al.,1 we adopted the strategy of using the limonene interaction parameters to represent the behavior of the class of compounds of terpenic hydrocarbons. In fact, this calculation strategy was based on our previous study regarding the deterpenation of model lemon essential oil systems. In this study, it was observed that the terpenic hydrocarbons represented by limonene, γ-terpinene, and β-pinene presented very similar physical-chemical behavior, which enabled us nullify the NRTL and UNIQUAC interaction parameters among these three components.18 This procedure was successfully used in the study of Koshima et al.,18 and it was used as the basis for calculations regarding lavandin oil systems. H



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Figure 5. Solubility, at 298.2 ± 0.1 K, of crude bergamot essential oil system composed by limonene (1) + linalyl acetate (2) + linalool (3) + ethanol (4) + water (5). Experimental: ■, solubility of solvent in the oil; □ solubility of oil in the solvent. Calculated: ------, NRTL; ·····, UNIQUAC. (a) w5S = 0.3217; (b) w5S = 0.3944; (c) w5S = 0.5066; (d) w5S = 0.6169.

Figure 6. Solubility, at 298.2 ± 0.1 K, of crude lavandin essential oil system composed by terpenic hydrocarbons (1) + linalyl acetate (2) + linalool (3) + ethanol (4) + water (5). Experimental: ■, solubility of solvent in the oil; □ solubility of oil in the solvent. Calculated: ------, NRTL; ·····, UNIQUAC. (a) w5S = 0.3559; (b) w5S = 0.4333; (c) w5S = 0.4960.

Qualitatively, the obtained experimental results are consistent with previous studies published by our research group8,9,18 and by Arce et al.26,27 and Gramajo de Doz et al.3 Additionally, it is very relevant to reinforce that in all the aforementioned studies, the phase equilibria issue was approached considering model systems, that is, mixtures of pure compounds that could represent the major compounds or compounds of interest in essential oils. In this work, the liquid−liquid equilibrium data of real systems composed of crude essential oils are reported, which highlights the new contribution of this manuscript.

Table 5. Mean Deviations between the Experimental and Calculated Compositions in Both Phases Δwb bergamot oil

lavandin oil

a

w5Sa

UNIQUAC

NRTL

0.3217 0.3944 0.5066 0.6169 global deviation 0.3559 0.4333 0.4960 global deviation

0.0210 0.0192 0.0314 0.0393 0.0289

0.0185 0.0181 0.0321 0.0392 0.0284

0.0827 0.0426 0.0654

0.1311 0.0412 0.0828

4. CONCLUSIONS Experimental liquid−liquid equilibrium data for systems containing crude bergamot and lavandin essential oils were obtained at 298.2 K. As observed by Chiyoda et al.1 in a previous study considering the compounds of interest for this work, linalool exhibits the largest distribution coefficient, followed by linalyl acetate and limonene. The higher water content in the solvent resulted in a lower distribution coefficient value and the consequent expansion of the biphasic region. Based on the reported experimental data, the fractionation of essential oils by liquid extraction using hydrous ethanol as the solvent would be more efficient for raw materials that possess a low content of linalool.

w5S = water mass fraction in the solvent. bCalculated according to eq 2.

interaction parameters of NRTL and UNIQUAC models used in the present study. The binary parameters adjusted to the bergamot oil model system by Chiyoda et al.1 possibly present difficulties in describing systems with high solubility, such as lavandin oil systems. This comment might explain the faults observed in the calculation of lavandin oil system compositions. In general, the behavior of the experimental data determined in this work is in accordance with the behavior of the model bergamot essential oil systems studied by Chiyoda et al.1 I



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eucalyptus essential oil by liquid+liquid extraction: Phase equilibrium and physical properties for model systems at T=298.2K. J. Chem. Thermodyn. 2014, 69, 66−72. (9) Oliveira, C. M.; Koshima, C. C.; Capellini, M. C.; Carvalho, F. H.; Aracava, K. K.; Gonçalves, C. B.; Rodrigues, C. E. C. Liquid-liquid equilibrium data for the system limonene + carvone + ethanol + water at 298.2 K. Fluid Phase Equilib. 2013, 360, 233−238. (10) Lago, S.; Rodríguez, H.; Soto, A.; Arce, A. Alkylpyridinium alkylsulfate ionic liquids as solvents for the deterpenation of citrus essential oil. Sep. Sci. Technol. 2012, 47, 292−299. (11) Rosa, P. T. V.; Meireles, M. A. A. Cost of manufacturing of supercritical fluid extracts from condimentary plants. In Extracting bioactive compounds for food products. Theory and applications; Meireles, M. A. A., Ed.; CRC Press: Boca Raton, FL, 2009; p 388. (12) Dupuy, A.; Athes, V.; Schenk, J.; Jenelten, U.; Souchon, I. Solvent extraction of highly valuable oxygenated terpenes from lemon essential oil using a polypropylene membrane contactor: potential and limitations. Flavour Frag. J. 2011, 26, 192−203. (13) Haypek, E.; Silva, L. H. M.; Batista, E.; Marques, D. S.; Meireles, M. A. A.; Meirelles, A. J. A. Recovery of aroma compounds from orange essential oil. Braz J. Chem. Eng. 2000, 17, 705−712. (14) Li, H.; Tamura, K. Ternary liquid−liquid equilibria for (water + terpene + 1-propanol or 1-butanol) systems at the temperature 298.15K. Fluid Phase Equilib. 2008, 263, 223−230. (15) Adams, R. P. Identification of essential oil components by gas chromatography/ mass spectrometry; Alluredbooks: IL, 2009. (16) Taylor, B. N., Kuyatt, C. E. Guidelines for the Evaluation and Expression of Uncertainty in NIST Measurement Results, NIST Technical Note 1297, 1994. (17) Marcilla, A.; Ruiz, F.; Garcia, A. N. Liquid-liquid-solid equilibria of the quaternary system water-ethanol-acetone-sodium chloride at 25 °C. Fluid Phase Equilib. 1995, 112, 273−289. (18) Koshima, C. C.; Capellini, M. C.; Geremias, I. M.; Aracava, K. K.; Gonçalves, C. B.; Rodrigues, C. E. C. Fractionation of lemon essential oil by solvent extraction: Phase equilibrium for model systems at T = 298.2 K. J. Chem. Thermodyn. 2012, 54, 316−321. (19) Stragevitch, L.; D’Avila, S. G. Application of a generalized maximum likelihood method in the reduction of multicomponent liquid-liquid equilibrium data. Braz J. Chem. Eng. 1997, 14, 41−52. (20) Franceschi, E.; Grings, M. B.; Frizzo, C. D.; Oliveira, J. V.; Dariva, C. Phase behavior of lemon and bergamot peel oils in supercritical CO2. Fluid Phase Equilib. 2004, 226, 1−8. (21) Fang, T.; Goto, M.; Sasaki, M.; Hirose, T. Combination of supercritical CO2 and vacuum distillation for the fractionation of bergamot oil. J. Agric. Food Chem. 2004, 52, 162−5167. (22) Andogan, B. C.; Baydar, H.; Kaya, S.; Demirci, M.; Ozbasar, D.; Mumcu, E. Antimicrobial activity and chemical composition of some essential oils. Arch. Pharmacal Res. 2002, 25, 860−864. (23) Rojo, S. R.; Martin, A.; Cocero, M. J.; Serra, A. T.; Crespo, T.; Duarte, C. M. M. Antimicrobial activity of lavandin essential oil formulations against three pathogenic food-borne bacteria. Ind. Crops Prod. 2013, 42, 243−250. (24) Langhals, H. Description of properties of binary solvent mixtures. In Similarity models in organic chemistry, biochemistry and related fields. Studies in Organic Chemistry; Zalewski, R. I., Krygowski, T. M., Shorter, J., Eds.; Elsevier Science Publishers: Amsterdam, 1991; Vol. 42, pp 288, 297. (25) Reichardt, C. Solvents and Solvent Effects in Organic Chemistry, 3 ed.; Wiley-VCH: Weinheim, Germany, 2003; p 426. (26) Arce, A.; Marchiaro, A.; Soto, A. Liquid-liquid equilibria of linalool + ethanol + water, water + ethanol + limonene, and limonene + linalool + water systems. J. Solution Chem. 2004, 33, 561−569. (27) Arce, A.; Marchiaro, A.; Martínez-Ageitos, J. M.; Soto, A. Citrus essential oil deterpenation by liquid-liquid extraction. Can. J. Chem. Eng. 2005, 83, 366−370.

Regarding the performance of the NRTL and UNIQUAC thermodynamic models, it was observed that both equations provided a good description of the phase compositions of the bergamot oil systems. For lavandin oil, the models were able to describe the trends in the behavior of the experimental data, especially for higher contents of water in the alcoholic solvents. The solubility of the systems appears to be an important factor in the performance of the NRTL and UNIQUAC interaction parameters. For the crude bergamot oil systems, the aforementioned parameters provide a satisfactory description of the phase composition. For the crude lavandin oil systems, which exhibited the highest solubility, both models failed in calculating some tie lines and the description of the phase composition was not as appropriate as that for the bergamot oil system. The set of binary parameters adjusted to the model system and used in this study to describe the compositions of real systems generally show satisfactory performance and could be employed in simulating the separation process. For systems that present high solubility, such as the lavandin oil systems, these parameters could be used as a first effort to simulate the liquid extraction deterpenation.

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AUTHOR INFORMATION

Corresponding Author

*Fax: + 55-19-3565-4343. E-mail: [email protected]. Funding

The authors wish to acknowledge FAPESP (Fundaçaõ de Amparo à Pesquisa do Estado de São Paulo −2010/20789-0, 2011/02476-7, 2012/15317-7), CNPq (Conselho Nacional de ́ Desenvolvimento Cientifico e Tecnológico -308024/2013-3), FINEP (Inovaçaõ e Pesquisa), and CAPES (Coordenaçaõ de ́ Superior) for the financial Aperfeiçoamento de Pessoal de Nivel support. Notes

The authors declare no competing financial interest.

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REFERENCES

(1) Chiyoda, C.; Capellini, M. C.; Geremias, I. M.; Carvalho, F. H.; Aracava, K. K.; Bueno, R. S.; Gonçalves, C. B.; Rodrigues, C. E. C. Deterpenation of bergamot essential oil using liquid-liquid. J. Chem. Eng. Data 2011, 56, 2362−2370. (2) Lago, S.; Rodríguez, H.; Soto, A.; Arce, A. Deterpenation of citrus essential oil by liquid-liquid extraction with 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ionic liquids. J. Chem. Eng. Data 2011, 56, 1273−1281. (3) Gramajo de Doz, M. B.; Cases, A. M.; Sólimo, H. N. (Liquid + liquid) equilibria for (water + linalol + limonene) ternary system at T = (298.15, 308.15 and 318.15) K. J. Chem. Thermodyn. 2008, 112, 1575− 1579. (4) Paroul, N.; Biasi, A.; Rovani, A. C.; Prigol, C.; Dallago, R.; Treichel, H.; Cansian, R. L.; Oliveira, J. V.; Oliveira, D. Enzymatic production of linalool esters in organic and solvent-free system. Bioprocess Biosyst. Eng. 2010, 33, 583−589. (5) Arce, A.; Marchiaro, A.; Rodríguez, O.; Soto, A. Essential oil terpenless by extraction using organic solvents or ionic liquids. AIChE J. 2006, 52, 2089−2097. (6) Gironi, F.; Maschietti, M. Phase equilibrium of the system supercritical carbon dioxide−lemon essential oil: New experimental data and thermodynamic modeling. J. Supercrit. Fluids 2012, 70, 8−16. (7) Beneti, S. C.; Rosset, E.; Corazza, M. L.; Frizzo, C. D.; Di Luccio, M. J.; Oliveira, V. Fractionation of citronella (Cymbopogon winterianus) essential oil and concentrated orange oil phase by batch vacuum distillation. J. Food Eng. 2011, 102, 348−354. (8) Gonçalves, D.; Koshima, C. C.; Nakamoto, K. T.; Umeda, T. K.; Aracava, K. K.; Gonçalves, C. B.; Rodrigues, C. E. C. Deterpenation of J


Fractionation of Bergamot and Lavandin Crude Essential Oils by

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