Journal of Supercritical Fluids 12 (1998) 59-67 ELSEVIER

Supercritical carbon dioxide extraction of Angelica archangelica L. root oil

Catalin Doneanu a, Gheorghe Anitescu b,* a Department of Organic Chemistry, Faculty of Pharmacy, 6 Traian Vuia Str., Bucharest, Romania

b Department of Chemical Engineering and Materials Science, Syracuse University, Syracuse, NY 13244, USA

Received 5 May 1997; received in revised form 19 August 1997; accepted 26 August 1997

Abstract

Angelica (var. Angelica archangelica L.) oil was isolated from grated fresh roots of the plant by supercritical fluid extraction using carbon dioxide and a two-stage fractional separation system. Throughout the extraction process the pressure and temperature were maintained at 120 bar and 40°C respectively. A 1 h static extraction step was followed by a 2 h dynamic extraction conducted at a flow rate of 0.5 kg h-‘. The extracted material was characterized by capillary gas chromatography-mass spectrometry using three different mass spectra libraries. More than 200 compounds were found in the extracted oil, of which 118 compounds were positively identified and four other compounds tentatively identified. 0 1998 Elsevier Science B.V.

Keywords: Angelica archangelica L.; Carbon dioxide; Capillary GC-MS; Essential oil; Supercritical fluid extraction

1. Introduction

Angelica (var. Angelica archangelica L.) is a herbaceous biennial or perennial plant of the umbel family, with tall stalks and large divided leaves. The roots and fruits are used in flavoring, perfumes, medicine, etc. It is specific to European flora, and it is cultivated mostly in France, Germany, Belgium, and the Netherlands.

Essential oil of angelica is usually obtained from the rhizomes and roots by steam distillation. This method yields O.l-1.0% of essential oil related to the angelica root material. A preliminary drying of the rhizomes and roots is not recommended

* Corresponding author. Tel.: (+ 1) 315 443 191; fax: (+ 1) 315 443 1243; e-mail: ganitesc@mailbox.syr.edu

0896-8446/98/$19.00 0 1998 Elsevier Science B.V. All rights reserved. PII SO896-8446(97)00040-5

because of the partial loss of the most volatile compounds. Further, by drying, some terpenes (especially a-phelandrene) become resinous. Therefore, the top fragrance notes of the oil, usually fresh and gently pungent, may be altered. Essential oil obtained from rhizomes and roots of angelica is a yellow liquid having a fresh, herba- ceous, and gently pungent aroma on an earthly and woody background.

There are many studies on the extraction and composition of angelica root oil [l-9]. In the early investigations, reviewed by Gildemeister and Hoffmann [ 11, only a small number of constituents were identified. The essential oil composition of angelica roots has been investigated by Klouwen and ter Heide [ 21, Taskinen and Nyktinen [ 31, For& [4], Srinivas [ 51, Kallio et al. [ 61, Nykgnen

60 C. Doneanu, G. Anitescu / Journal of Supercritical Fluids I2 (1998) 59-67

et al. [7], Kerrola and Kallio [8], and Kerrola material-solvent ratio, the method of feeding the et al. [9]. However, the detailed effects of both the solvent, conditions of extraction (pressure, temper- plant’s environmental conditions and extraction ature, time, flow rate), preparation of raw material parameters on the yield and composition of the and separation conditions, etc. Analysis of the oils’ extract of angelica flavor have not yet been eluci- composition revealed that oils extracted under dated. A large variability in the relative amounts different SFE conditions possessed widely different of the compounds was found to depend on the percentage compositions. Qualitative aroma tests stage of plant development and the kind of strains showed that the oil obtained at optimum SFE and freshness of the roots at the time of extrac- conditions had a fragrance that better resembled tion [9]. the flavor profile of the starting material.

Throughout the investigations, angelica root oil was found to have a very complex composition. The bouquet aroma of this oil is the result of the combination of the aromas of a very large number of components. Thus, it is very important that the native natural proportion of the components is maintained during any extraction procedure. Unfortunately, the traditional extraction tech- niques based on liquid solvents or steam distilla- tion were found to present some disadvantages. For example, the steam distillation procedure cannot recover the pungent compounds because these are thermally degraded to produce volatile aldehydes or ketones. Some of the aromatic com- pounds are also known to be affected by heat. The essential oil when extracted with liquid solvents lacks a strong aroma due to the loss of volatile compounds during the evaporation process of the solvents. Further, the alcohol extraction of the flavors was found to produce artifacts by esterifi- cation, etherification, and/or acetal formation [ 31.

Angelica root oil has been isolated by SFE (12 MPa/SO”C) into three fractions with distinctly different compositions by three successive extrac- tion steps and by using a single separator [9]. Obviously, each of the fractions was found to present a composition which did not resemble that of the natural aroma composition. To perform that requirement, the fractions must be mixed after completing the extraction process and the removal of undesired compounds.

Supercritical fluid extraction (SFE), mainly by supercritical carbon dioxide (SC-C02), can be used to extract volatile oils from natural products and does not produce substantial thermal degradation or solvent pollution/alteration of the extracts [lo]. Nevertheless, a high density of supercritical fluid (SCF) and one-stage subcritical separation is unsuitable due to the simultaneous extraction of many undesired compounds, such as fatty acids and their esters, cuticular waxes, coumarins, etc. [ 111. SFE performed in multiple steps by increasing the SCF density and a multistage separation tech- nique give superior quality products compared with those obtained by the traditional techniques [ 12,131. However, there are many parameters that must be considered in the SFE procedure. These include the type of solvent/cosolvent, raw

The aims of this study were to use an appropriate extraction procedure to obtain a more detailed knowledge of the proportion of fragrant constitu- ents of angelica roots and to elucidate the actual aroma composition of a fresh root extract. Therefore, this study reports an SFE technique to isolate the volatile oil, consisting of two successive extraction stages (static and dynamic), and a two- stage separation process. Approximately 200 com- pounds were separated from extracted oil by a gas chromatography-mass spectrometry (GC-MS) analytical method, and more than half have been identified. Throughout the extraction process, nei- ther coumarins nor psoralens were detected in the GC traces of the extracted material, except for a small amount of osthol. Also, neither waxes, nor large amounts of long-chain fatty acid esters, nor ethers were found. Furthermore, extracts with a high resemblance to the native aroma of angelica roots were obtained.

2. Experimental section

2.1. Materials

Fresh angelica roots of var. Angelica archangel- ica L. cultivated in Romania were used 1 day after

C. Doneanu, G. Anitescu / Journal of Supercritical Fluids 12 (1998) 59-67 61

harvesting. Grated samples of 500 g each were placed in a stainless steel sieve basket to prevent carryover of particulates. Particle size was non- uniform because of the particular procedure of grating a fresh root material. Although grated material was passed through 1 mm diameter grater holes, the length of the plant fibers was variable (N l-4 mm). Carbon dioxide of 99.5% purity was used by passing through a filter filled with ZSM-20 molecular sieves for a further purification. The molecular sieves were conditioned before using a new cylinder with carbon dioxide by heating in an oven at 200°C for 7 h.

2.2. Apparatus andprocedure

SFE experiments were performed on an appara- tus mainly consisting of a thermostatic extractor (1 1 internal volume) and two separators operated in series (100 ml and 300 ml). More details on the SFE apparatus were provided in a previous paper [ 131. No pump or compressor was used to deliver SC-CO,. The system is essentially maintenance- free, with virtually no moving parts.

In the experimental runs, the extractor was charged with 500 g of grated roots of angelica plant, and carbon dioxide was delivered into the extractor by controlled heating of a siphon-type cylinder. In the first step, the extractor was loaded with carbon dioxide up to a desired pressure and thermostatically controlled at a given temperature during a 1 h period of time (a static period). In the second step, a carbon dioxide flow rate of 0.5 kg h-’ (measured at the outlet of the appara- tus) was used during all the tests in a downflow mode. Downflow of SCF through the fixed bed of plant material is more effective than upflow, because in this mode any condensate is simply pushed out of the bottom of the extraction vessel, and the resultant oil content recovered [ 141. The pressure control valve at the outlet of the extractor is moderately warmed by heating tape to prevent plugging by freezing due to the Joule-Thomson effect produced by flowing carbon dioxide. Extracted fractions from the extractor were precipitated/condensed in two separators oper- ated in series at pressures/temperatures of 6.0 MPa/lO”C and 3.0 MPa/O”C. Extractions

performed at various densities of carbon dioxide showed that an extraction at 12.0 MPa and 40°C (1 h static process followed by 2 h dynamic pro- cess) was optimum in order to have an acceptable yield and a composition containing a minimum of unwanted co-extracted compounds. Using these conditions, the undesired compounds, co-extracted during the designated extraction time, were precipi- tated selectively in the first separator, and the essential oil was recovered in the second separator. The water collected in the second separator was removed by addition of sodium sulfate.

2.3. GC-MS

The GC-MS apparatus was a Fisons Instruments MD 800 gas chromatograph-mass spectrometer equipped with a split/splitless injector (maintained at 250°C) and with a fused silica SPB-5 column (50 m x 0.32 mm i.d. x 0.25 urn film thickness, Supelco, Bellefonte, PA, USA). Helium was used as the carrier gas, with an inlet pressure of 70 kPa, and the septum purge was 4 ml mini. The split ratio was 1:lOO and the volume of each of the injected samples was 0.1 ~1. The GC oven was programmed to operate from 60 to 240°C (20 min) at 3°C min- ‘. The ion source temperature was 200°C and the interface temperature was 250°C. Data acquisition was performed with MassLab software for the mass range from 35 to 480 a.m.u. with a scan rate of one scan per second. The ionization energy of electrons was 70 eV. The identification of compounds was based on a com- parison of experimentally obtained mass spectra with NIST, WILEY-6 and TERPENE mass spectra libraries, using relative retention indices already established [ 151. In a second run, the oil was injected into the same column, using a flame ionization detector. The percentage composition was computed from peak areas without correction factors. Finally, by using the same temperature program, a mixture of n-alkanes from Ca to C& was analyzed. The retention times were then used for assigning Kovats retention indices of identified compounds in the angelica root oil extracts [ 16,171. In order to determine the ratio of the co-eluted compounds, limonene and P-phellandrene, the oil was solved in hexane

62 C. Doneanu, G. Anitescu /Journal of Supercritical Fluids 12 (1998) 59-67

Table 1 Identification and quantification of compounds contained in the Angelica archangelica L. root oil compared with literature data

No. Compound Kovats index Percentage composition

C” Cb CC Cd

1 Isobutyraldehyde 591 0.01 2 2-Methyl-3-buten-2-01 611 0.01 3 2-Methyl furane 615 trace 4 Isovaleraldehyde 649 0.02 5 2-Methyl 2-butanol 659 0.03 6 Hexanal 798 0.02 7 Isovaleric acid 819 trace 8 2-Vinyl-5-methyl furane 826 trace 9 2-Methyl butyric acid 830 trace

10 2-Pentenoic acid 873 0.01 11 2-Heptanone 886 trace 12 Tricyclene 925 0.02 13 a-Thujene 928 0.43 14 2-Methyl-5-isopropyl furane 933 0.01 15 a-Pinene 936 16.66 16 2,CThujadiene 945 0.01 17 a-Fenchene 949 trace 18 Camphene 951 1.09 19 Verbenene 956 0.57 20 Hexanoic acid 969 0.02 21 o-Cymene 972 0.04 22 Sabinene 975 0.62 23 /+Pinene 980 1.12 24 Myrcene 990 3.91 25 2-Carene 1006 0.13 26 a-Phellandrene 1008 11.27 27 3-Carene 1013 8.69 28 a-Terpinene 1018 0.31 29 m-Cymene 1022 0.09 30 p-Cymene 1026 5.56 31 Limonene 1030 13.12 32 p-Phellandrene 1030 8.92 33 cis+Ocimene 1036 2.05 34 trm+Ocimene 1043 5.43 35 y-Terpinene 1059 0.64 36 Benzyl formate 1076 0.02 37 Dimethyl styrene (isomer) 1082 0.07 38 a-Terpinolene 1090 0.78 39 a-p-Dimethyl styrene 1090 0.78’ 40 Camphen-6-one 1098 0.05 41 Linalool 1099 0.09 42 Perillene 1101 0.03 43 1,3,8-p-Menthatriene 1113 0.01 44 cis-allo-Ocimene 1129 0.07 45 trans-Verbenol 1146 0.22 46 n-Amy1 benzene 1158 0.02 47 6-Butyl- 1 ,4-cyclopentadiene 1160 0.19 48 a-Phellandren-8-01 1167 0.20 49 (E,Z) 1,3,5-Undecatriene 1173 0.10 50 Terpinen-4-01 1179 0.14 51 p-Cymen-7-ol(cuminylalcoho1) 1181 0.12

0.60 0.90

0.55

6.50

0.05 24.0’

17.10 24.0’

0.38 0.45 1.30

6.98 0.73 1.83

0.50 3.28

20.20 0.76 1.30 1.25 5.35 7.6”

1.35 7.6” 7.80 10.1

0.07

0.86 2.85 8.45

0.43 0.75

0.65 9.8 4.40 13.2 6.75 10.0

1.25 3.10 2.68 0.55 0.11

0.30 0.55 0.16

0.01

0.64

0.40

0.50 0.45 trace

0.02

C. Doneanu, G. Anitescu 1 Journal of Supercritical Fluids 12 (1998) 59-67 63

Table 1 (continued) Identification and quantification of compounds contained in the Angelica archangelica L. root oil compared with literature data

No. Compound Kovats index Percentage composition

C” Cb CC Cd

52 p-Cymen-8-01 1184 0.10 53 Sabina ketone 1187 0.18 54 a-Terpineol 1192 0.22 55 Tyrtenal 1198 0.41 56 Sabinol 1203 0.23 51 Thujol 1206 0.02 58 trans-Piperitol 1209 0.10 59 Verbenone 1211 trace 60 Carve01 1219 0.03 61 Chrysanthenyl acetate 1223 0.01 62 cis-3-Hexenyl isovalerate 1230 trace 63 u-Phellandrene epoxide 1238 0.05 64 Cuminyl aldehyde 1241 0.04 65 Carvone 1245 0.03 66 Carvotanacetone 1249 0.19 67 Piperitone 1255 0.07 68 Isoascaridol (?) 1266 0.02 69 Phellandral 1217 0.27 70 Bornyl acetate 1288 0.98 71 Thymol 1289 trace 12 trans-Verbenyl acetate 1293 0.16 13 Carvacrol 1299 0.34 14 cis-Pinocarvyl acetate 1301 0.02 15 trans-Carvyl acetate 1337 0.06 16 trans-Piperitol acetate 1341 0.14 II Terpenyl acetate 1351 1.23 78 a-Cubebene 1355 0.03 19 Eucarvone 1358 0.01 80 cis-Carvyl acetate 1363 0.01 81 Longicyclene 1376 0.11 82 a-Copaene 1383 1.16 83 B-Elemene 1397 0.21 84 n-Tetradecane 1400 0.01 85 Sativene 1404 0.02 86 Piper&one oxide (?) 1414 0.07 87 l3-Cedrene 1424 0.11 88 8Caryophyllene 1428 0.14 89 Octyl isovalerate 1434 0.01 90 Thujopsene (widdrene) 1441 0.05 91 a-Elemene (?) 1446 0.01 92 P-Famesene 1458 0.16 93 a-Humulene 1463 1.20 94 y-Muurolene 1484 0.05 95 Germacrene-D 1491 1.13 96 g-Selinene 1496 0.03 97 a-Zingiberene 1499 0.16 98 cl-Muurolene 1507 0.59 99 8-Bisabolene 1513 1.13

100 &Cadinene 1530 0.31 101 cc-Copaen-l l-ol 1549 0.45 102 Elemol 1555 0.17

1.28 0.25 0.31

trace

1.96 0.11

1.73

0.02

0.40 2.36 2.10 0.73

0.46

0.17 0.03

0.38 0.20

0.05

0.63 0.38

1.10 1.91 3.55 0.9

0.25 1.15

0.20 trace 0.40

trace 0.23

1.08

0.50 1.93 0.33

0.15 0.50 0.04 0.26

0.10

1.28 0.98 4.08 1.35

1.2 0.72 0.51 0.46

0.30 0.18

64 C. Doneanu, G. Anitescu / Journal of Supercritical Fluids I2 (1998) 59-67

Table 1 (continued) Identification and quantification of compounds contained in the Angelica archangelica L. root oil compared with literature data

No. Compound Kovats index Percentage composition

C” Cb

103 Germacrene-B 1568 0.10 1.15 104 Spathulenol 1587 0.03 1.10 105 June01 1591 0.14 106 Caryophyllene oxide 1594 0.02 107 n-Hexadecane 1600 0.03 108 a-Copaen-S-01 1605 0.01 0.20 109 Cedrol 1615 0.01 0.25 110 Humulene epoxide III 1620 0.11 111 Dehydroaromadendrene 1625 0.01 112 Isomethyl-a-damascone 1629 0.01 113 y-Eudesmol 1631 0.02 114 13-Tridecanolide 1636 0.82 2.25 115 cc-Muurolol 1650 0.02 116 B-Eudesmol 1661 0.17 0.50 117 3-Butylidene phthalide 1678 0.04 118 12-Methyl-13-tridecanolide 1692 0.33 0.50 119 Pentadecanolide 1844 0.49 4.30 120 Dimyrcene 1958 0.02 121 Heptadecanolide 2051 0.06 122 Osthol 2144 0.23 7.60

Unidentified compounds (%) 2.17

(?) Compounds tentatively identified. ’ This work, SFE method (12.0 MPa/40”C). b Kerrola et al. [9], Soxhlet extaction. c Kerrola et al. [9], SFE method (12.0 MPa/SO”C). d Taskinen and Nykanen [3]: extraction with ether-pentane followed by steam distillation. ’ The percentage represents the sum of two co-eluting peaks.

CC

trace

0.10 0.10

1.50

trace

0.65 2.90

1.60

Cd

0.45

0.21

0.37

trace

(l/100) and a GC run at 80°C (20 min) followed by a rate of 25”Cmin’ to 240°C (20min) was performed.

3. Experimental results and discussion

The main goal of this study was to obtain the best quality and the maximum yield of the angelica oil by an optimal selection of SFE parameters.

These conditions precluded contamination of the liquid extract collected in the second separator. A yield of 0.18% was measured by weighing this fraction after water removal by anhydrous sodium sulfate and by weight of the fresh root sample charged in the extractor. When only a dynamic procedure was used, carbon dioxide left the extrac- tor unsaturated with biocompounds in the first step of the extraction process. Therefore, a 1 h static step was completed before the dynamic step.

As expected, fresh root angelica oil was found The identification of the compounds constituting to have a very complex composition. Its GC trace angelica root oil and their GC area percentages is shown in Fig. 1, with compound identifications were reported in the first column of data in Table 1. reported in Table 1. A series of runs was performed In the next columns of data are reported the to assess the optimal extraction conditions: compositions of angelica oil extracted from dried 12.0 MPa and 40°C for the extractor (1 h static roots by different techniques: Soxhlet extraction period of time and 2 h dynamic process) and performed by Kerrola et al. [9]; SFE method 6.0 MPa/lO”C and 3.0 MPa/O”C for the separators. (1.20 MPa/SO”C) performed by the same authors;

C. Doneanu, G. Anitescu / Journal of Supercritical Fluids 12 (1998) 59-67 65

lO(

%

C

18 23-34 82 93

Fig. 1. GC trace of the angelica (var. Angelica archnngelica) root oil (numbering of the peaks corresponds with the compounds in Table 1).

extraction with ether-pentane followed by steam distillation, performed by Taskinen and Nykanen [ 31. The second column of data shows averaged results reported for four various origins of angel- ica, while in the next column, results for the first two SFE fractions out of three were averaged.

The results reveal a large variability in the relative amounts of the compounds, particularly between our results and those reported by Kerrola et al. The percentage composition for commonly identified compounds reported by Taskinen and Nykanen appears to be in a reasonable concor- dance with ours. The results also show a strong dependence of the oil composition on a number of parameters, such as variety of wild or cultivated angelica strains, stage of the plant development, freshness of the roots at the time of the extraction, environmental conditions during the plant devel- opment, extraction methods, analytical pro- cedure, etc.

The oil obtained from fresh roots of var. Angelica archangelica L. was examined in this study by capillary GC-MS using three mass spectra libraries: NIST, WILEY-6 and TERPENE. A total of approximately 200 compounds were

separated, of which 118 compounds were positively identified and another four were tentatively iden- tified. To allow a comparison, the main families of compounds identified from Table 1 are summa- rized in Table 2. Besides the hydrocarbons (monot- erpenes and sesquiterpenes) and their oxygenated compounds, Table 2 also presents the specific angelica macrocyclic lactones and total undesired coumarins co-extracted with the oils. Compounds collected in the first separator were identified quali- tatively, but only a rough estimation of the percen- tage composition was made. The SFE process was optimized by quantification of the desired and undesired compounds in the second separator to obtain maximum and minimum percentages respectively. These data indicate reasonably good agreement between our results and those reported by Taskinen and Nykanen.

Monoterpene hydrocarbons represent the larger fraction of the angelica root oil constituents (- 80%). It was previously reported that the main proportion of angelica root oil consists of monoter- pene hydrocarbons (up to 88%) [4]. Considerably smaller proportions of monoterpenes were detected in the Soxhlet extracts of angelica roots by Kerrola

66 C. Doneanu, G. Anitescu / Journal ojSupercritical Fluids 12 (1998) 59-67

Table 2 Percentage comparison of main families of compounds extracted by different methods (as shown in Table 1)

Compound family Percentage composition

C” Cb

Monoterpene hydrocarbons 81.57 34.39 Sesquiterpene hydrocarbons 6.13 15.01 Oxygenated compounds 6.91 20.43 Lactones 1.70 7.05 Others 2.99 23.12 (Coumarins) (0.23) (8.40)

’ This work, SFE method (12.0 MPa/40”C). b Kerrola et al. [9], Soxhlet extaction. ’ Kerrola et al. [9], SFE method (12.0 MPa/SO”C). d Taskinen and NykZnen [3]: extraction with ether-pentane followed by steam distillation.

c” Cd

69.60 82.28 10.45 6.75 6.15 4.98 5.05 0.82 8.75 5.17

(2.05)

et al. [9]: 24 to 46%. Nykanen et al. [7] reported 28% monoterpenes in an angelica root commercial oil. The main component in our fresh root angelica oil isolated by SFE is a-pinene (16.66%). Its isomer, S-pinene, is present at a lower percentage ( 1.12%). As pinene and limonene oxidize to pro- duce citronellol, carvone, piperitone, and carvacrol [ lo], their high percentages in our oil compos- ition show the lack of oxidation phenomenon. Note that a-phellandrene is also present in a high amount (11.27%), whereas its isomer, (3-phellandrene, was estimated quantitatively in a first step because of the co-elution with limonene (together they represent 22.04%). From a later GC analysis, limonene and B-phellandrene were found to represent 13.12% and 8.92% respectively. Other monoterpene hydrocarbons identified in a large amount were: 3-carene (8.69%), p-cymene (5.56%), truns-p-ocimene (5.43%) and its geometric isomer, ci,+ocimene (2.05%), myrcene (3.91%), and cam- phene (1.09%). The difference in odor of the angelica root oils can be attributed to the composi- tional differences of the volatiles, especially in the relative amounts of various monoterpene hydro- carbons [4]. It can be assumed that a high number of different monoterpene compounds indicates a high quality of the oil aroma [9].

Sesquiterpene hydrocarbons represented 6.73% of the angelica oil composition, in very good concordance with the percentage reported by Taskinen and Nykiinen (6.75%). The main compounds identified are: a-humulene (1.23%),

a-copaene ( 1.16%), germacrene-D ( 1.13%), and B-bisabolene (1.13%).

Oxygenated compounds of terpene hydro- carbons confer special characteristics to the angel- ica root oil, such as particular odor notes and stability of the oil against alteration. The com- pounds extracted by SFE in significant amounts are: terpenyl acetate (1.23%), bornyl acetate (0.98%), a-copaen- 1 l-01 (0.45%)) carvacrol (0.34%), and phellandral (0.27%).

Macrocyclic lactones were found in a relatively low percentage (1.70%), but they are very impor- tant compounds in angelica root oil. The musk- like odor of this oil is generally attributed to the lactone of 15-hydroxypentadecanoic acid. Besides pentadecanolide (0.49%), three other macrocyclic lactones were found in the oil isolated by SFE from fresh roots of angelica var. archangelica L.: 13-tridecanolide (0.82%), 12-methyl-13-tride- canolide (0.33%) and heptadecanolide (0.06%).

Coumarins as undesired compounds were found in a very low concentration in our SFE oil (only osthol, 0.23%) compared with those found in the oils extracted by Kerrola et al. [9]: 2.05% in SFE oils and 8.40% in the oils extracted by the Soxhlet method.

A qualitative sensory analysis of a number of fractions extracted at different SFE conditions showed that the fraction extracted under the above-mentioned conditions had the best quality compared with the other fractions and a commer- cially available sample of the essential oil.

C. Doneanu, G. Anitescu / Journal ofSupercritica1 Fluids 12 (1998) 59-67 6-l

4. Conclusions

A two-step SFE process (1 h static period at 12.0 MPa/40”C followed by 2 h dynamic period at 12.0 MPa/40”C and 0.5 kg CO2 h-‘) coupled with a two-stage separation process (6.0 MPa/lO”C and 3.0 MPa/O”C) was selected as an optimum pro- cedure to extract a very complex oil from the fresh roots of Angelica archangelica L. By this pro- cedure, approximately 200 compounds were sepa- rated by capillary GC-MS, of which 118 were conclusively identified and four were tentatively identified. The aroma provided by this composition was found to have the highest quality when com- pared with other fractions extracted under different conditions.

The advantages of SC-CO, extraction over steam distillation or liquid solvent extraction include: no thermal degradation of most of the labile compounds; a minimum coextracted amount of undesired compounds; no production of arti- facts; and no solvent contamination.

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