Indian Journal of Chemical Technology Vol. 21, July 2014, pp. 290-297
Process optimization of sandalwood (Santalum album) oil extraction by subcritical carbon dioxide and conventional techniques
Omprakash H Nautiyal* Department of Chemical Engineering, Institute of Chemical Technology (UDCT), NM Parikh Marg, Matunga, Mumbai 400 019, India
Received 15 April 2013; accepted 28 March 2014
o Sandalwood oil has been extracted using subcritical state carbon dioxide (SC-CO2) at 200 bars and 28 C using the two experimental conditions, and the fractionation of the extract is analyzed intermittently. Comparative studies with regards to extraction using steam distillation, hydro distillation, soxhlet extraction and pre-treatment studies have also been carried out. All these studies reveal that the subcritical carbon dioxide extraction is much more efficient in terms of physical properties of the oil as compared to commercial sandalwood oil. Acid value of the liquid CO2 extracted oil is found to be the best next to the value of ethyl alcohol extracted oil. SC-CO2 yields 4.11% of oil in the first hour, 1.21% in second hour, 0.89% in third hour and 0.30% finally in the fourth hour. The first hour gives α-santalene (0.55%), β-santalene (1.30%), α-santalol (51.30%), β-santalene (27.94%); second hour gives 0.48, 1.08, 54.50, 28.16% third and fourth hour give 1.00, 1.92, 50.27, 26.18% and 1.14, 2.17, 51.99, 26.76% respectively. Benzene extraction yields 3.01% of an absolute out of 6.30 g of concrete, diethyl ether yields 2.58% of an absolute out of 5.25 g of concrete, EtOH yields 3.70% of an absolute out of 10.90 g of concrete (under the 5 hour of process time). Hydro distillation (alkaline treated) yields 2.68% of sandalwood oil in 48 h, steam distillation gives 1.60% of sandalwood oil in 10 h of process time. Yield of 4.11% is obtained by SC-CO2 only.
Keywords: Carbon dioxide, Oil extraction, Sandalwood oil, Santalum album, Subcritical state
Sandalwood oil has a very good fixative properties solvents and allowable solvent residues in food and applications in classic blender fixatives. It has a and feed materials with increasing energy costs. delicate aroma and can be blended in small quantities The future of many technology-oriented processes without altering the dominant fragrance. A minimum including natural flavour and fragrance extraction of 90% santalol content is supposed to be present in will be significantly affected by these issues. the sandalwood oil to make it saleable as premium Therefore SC-CO2 may play an important and lead quality in market. Conventionally steam distillation is role as ecofriendly technology1,2. employed for recovering sandalwood oil which yields 3.6% oil after 24 h of distillation, whereas subcritical Subcritical fluid extraction is an extraction process utilizing a fluid as an extract temperature below carbon dioxide (liquid CO2) extraction yields much higher yield than that with steam distillation within its critical temperature and pressures exceeding 1 h of process time. Sub critical processed oil its critical pressure. During the past three decades, contains high yield of santalol than that obtained researchers have investigated the underlying fundamentals and process applications of subcritical with steam distillation. In the light of high demand 1,2 of high quality sandalwood oil high-tech sub critical fluid as solvents . It is possible to separate a multi- component mixture when a subcritical fluid is used CO2 extraction process was investigated. These investigations were also compared with various as an extractive solvent considering the differences conventional techniques1,2. in volatilities of components (Salient features of The past few decades saw the emergence of distillation) and the differences in specific interaction several noteworthy trends in processing products between the mixture components and the subcritical from plant materials and their enhanced customer solvent (salient features of solvent extraction). concern for the quality such as flavour, fragrance, The application of subcritical solvents is based odour, colour, stringent government regulations on on the experimental observations that many gases exhibit enhanced solvating power when compressed —————— 1-3 *E-mail: [email protected] to conditions above and below the critical point . NAUTIYAL: PROCESS OPTIMIZATION OF SANDALWOOD OIL BY SC-CO2 291
The design of commercial super/subcritical plants container where the components get separated on unit operations and designed specifications are important density basis. As oil is less dense, it floats over for extractions of flavour materials like sandalwood oil. the water surface and separated out on the gravity Under subcritical conditions, the density and viscosity basis. of the solvent are comparatively high and essential for the bulky mass materials like sandalwood oil. This Analysis of sandalwood oil facilitates the contact time of the process to be as low as The oil extracted by all techniques was analyzed 2 h, as investigated in this study1-3. by gas chromatography (Perkin-Elmer-8500). Sandalwood oil, being precious oil, is in high Column specification and temperature programme demand in the national and international markets. were column SE30(10%) on chromosorb W, column It is usually steam distilled and its major constituents material S.S, column length 4m, internal diameter α-santalols, β-santalols, α-santalenes and β-santalenes 1/8 mm, injector temperature 300°C, FID temperature are lost in the water during distillation, resulting in 300°C, flow rate of N2 38 mL/min, temperature inferior quality sandalwood oil. This study has been programming 100-250°C at 6°C/min. of temperature. undertaken to evaluate the quality and yield of oil Its physical properties were determined using Bausch using subcritical carbon dioxide and the findings are Lomb refractometer for refractive index. compared with those of the conventional techniques. Theory of SC- CO technology and principle Sandalwood oil obtained by all the extraction 2 Supercritical CO2 extraction means CO2 goes to technology is subjected to an extensive physical a supercritical phase after pressurization and determination. heating temperature above critical points. CO2 at supercritical phase has solubility power similar to Experimental Procedure liquid organic solvents, but with higher diffusivities, Sandalwood chips were provided by the Malladi higher transfer efficiency, lower viscosities, and Drugs & Pharmaceutical Limited along with the lower surface tension. With advantages of commercial sandalwood oil for comparative details. non-toxic, colourless, odourless, incombustibility, Equipments for the conventional processing were non-photochemical reaction, ecofriendly and easy purchased from the Indian suppliers of Borosil make, recycling, CO2 is now considered as the best solvent including soxhlet extractor, Dean-Stark (moisture for supercritical fluid extraction technology4,5. contents), Clevenger apparatus for hydro distillation. Steam distillation pilot plant of prototype was used. Green environmental protection technology Pilot plant for supercritical carbon dioxide extraction Supercritical CO2 extraction has no disadvantages was imported from UHDE, GmbH, Germany with of traditional extraction method. The biological 1 L capacity of extractor and separator each. activity is easy to be damaged in high temperature distillation extraction, the organic solvent left in Pulverization of sandalwood solvent extraction will influence the purity of extract, Sandalwood chips were pulverized in the pulveriser and the aroma of esters is easy to vanish away in to obtain powder of 40 mm in size. It was charged expression extraction. Supercritical CO2 extraction into the extractor of SCF pilot plant and then operated can extract high purity natural compounds easily. at subcritical state at 28°C to study the quality There are no solvent residues and little thermal and yield of the oil. Parallel experimental studies degradation of sensitive compounds occurs. were also performed using hydro distillation, steam- Separation and purification of totally natural and distillation, solvent extraction (Soxhlet apparatus) to healthy compounds can also be achieved. study the evaluation of the extracted oil. Physical Supercritical CO2 extraction is the green and properties of the extracted oil were determined epoch-making technology today and tomorrow4,5. from the quality and fragrance point of view. While extracting with solvents concrete of the Advantages sandal was obtained, which was then hydro distilled The technology affects bioactive ingredients to obtain the essential oil. extraction with lower viscosity and higher penetration Pilot scale steam-distillation, as commercially to the matrix. Low temperature extraction condition used for the recovery of the oil, was also carried out. results in less degradation of thermally-labile The oil thus distilled was collected in the Florentine components in the extracts. Green solvent with CO2 292 INDIAN J. CHEM. TECHNOL., JULY 2014
shows recovery rate over 95%. No solvent residue Results and Discussion is found in the extract. This means lower operating Sandalwood oil extraction with SC- CO2 costs for clean-up and the reduction in Experiments were conducted employing liquid post-processing steps. It is non-toxic, highly safe, carbon dioxide at 28oC temperature and 200 bars non-flammable and non-explosive. Selective pressure. Pulverized sandalwood of 40 mm size was extraction is obtained by manipulating the charged. Flow rate of solvent is 5 kg h-1 and batch operating conditions, viz. temperature, pressures, time 4 h. In the first set of experiments, the yield of flow rate, batch time and ease of intermediate oil obtained was 3.76wt%. The peak areas of fractionations4,5. α-santalene and β-sanatlene were 0.34 and 2.14% respectively, whereas area per cents of α-sanatlol Thermodynamic state of supercritical fluid and β-sanatlol were 43.78 and 22.81 respectively. The solvent power of supercritical fluid can be In another experiment, conditions were kept similar related to the solvent density in the critical region. but the oil was collected at the interval of 1 h. Hence, This statement can be rationalized by considering the in the first hour 4.11 g oil was extracted, 1.21 g in density behaviour of a pure component, at a reduced the second hour, 0.89 g in the third hour, and 0.30 g temperature (T ) ranging 0.8-1.55°C and pressure (P ) R R in the fourth hour. Thus, total 6.51 g of the oil was ranging 0.1-10 mPas. The density of the solvent can -3 extracted in batch time of 4 h. The oil obtained was change from a value of about 0.1kg m (gas like 6,7 3.83wt% of the material charged . density) to about 2.5 kg m-3 (a liquid like density). GC analysis shows that the peak areas of major As the reduced densities become liquid like, the constituents, α-santalene and β-santalene extracted supercritical fluid begins to act as a liquid solvent. in the first hour were 0.55 and 1.30% respectively, When operating in the supercritical region both whereas peak areas for α-santalol and β-santalol were temperature and pressure can be used to regulate 51.30 and 27.94% respectively. In the second hour, the density and therefore, the solvent power of the peak areas for α-santalene and β-santalene were a supercritical fluid. In supercritical fluid extraction, 0.48 and 1.08%, and those of α-santalol and β-santalol the supercritical fluid (SCF) region for a component were 54.50 and 28.16%. In the third hour, the peak is strictly defined as that region of temperature and areas of α-santalene and β-santalene were 1.00 and pressure greater than or equal to critical temperature 1.92%, and those of α-santalol and β-santalol were and critical pressure respectively of the pure 50.27 and 26.18% respectively. Finally, in the fourth component. The SCF region of interest for practical hour of extraction, the peak area of α-santalene, considerations is considered less rigorously at β-santalene and α-santalol, β-santalol was 1.14, conditions bounded approximately by 0.9
pale yellow with pleasant odour. The yield of the oil Effect of alkalinity on the yield of sandalwood oil using hydro was found to be less since the oil sacs remained distillation unexposed. In spite of softening the sandalwood In this part of study, sandalwood powder chips for a long time, it was difficult for the steam (40 mm size) was charged for hydro distillation, to pierce through medullar ray cell, vessels, wood utilizing alkaline water. The extraction was carried fibres and wood parenchyma containing oil as it out for 48 h. The oil recovered was 2.68wt%. The was unpulverized. Gas chromatograph analysis yields of α-santalene and β-santalene were 4.25 and showed the presence of α-santalene and β-santalene 3.01% and those of α-santalol and β-santalol were in trace amount, whereas the contents α-santalol 41.90 and 19.89% respectively. α-santalene and and β-santalol were 48.38 and 28.73% respectively9,10 β-santalene extracted were high. The alkaline medium (Table 2, Section 1). was used since the pH of water during hydro distillation plays a major role on composition of Earlier hydro distilled sandalwood was dried, essential oil. Acidity of water causes transformations pulverised and then extracted employing of thermo labile monoterpenes. Neutral or alkaline Soxhlet apparatus. The powder was extracted medium minimizes the formation of artefacts during using toluene for 5.15 h in soxhlet apparatus. distillation (Table 2, Section 2)13,14. 5.33wt % of yellowish red concrete was obtained and further yielded the absolute 0.37 wt % Yield of sandalwood oil from un pulverized sandalwood using (solvent extraction). α-santalene, β-santalene and hydro distillation α-santalol, β-santalol were 0.36, 0.83, 39.71 In this study, extraction of sandalwood oil was and 19.76% respectively, as analyzed by GC. carried out for 38 h using preimmersed whole The insoluble resinous mass left after the sandalwood chips in hot water at 95oC for 24 h. extraction was then hydro distilled for 12 h. The yield The yield of the oil obtained was 1.56wt% and the of the oil obtained was 1.05wt%. The oil obtained colour of the oil was pale yellow with pleasant was less odourant. α-santalene, β-sanatlene, α-sanatlol odour with α-santalol 56.73%, β-santalol 27.10%, and β-sanatlol were 3.98, 4.87, 38.47 and 20.42wt% α-santalene 0.30% and β-santalene 0.91%. Structures respectively. Hence, the net oil recovered of major constituents responsible for woody odour was 3.13% (refs 9,10). and medicinal values are presented in Fig. 115,16. In this case, sandalwood was pulverized to 40 mm Steam distillation size (particle length 9 mm, diameter 3-4 mm) and charged for the hydro distillation. Hydro distillation Effect of batch time on extraction of sandalwood oil using pilot was carried out for 30 h. The oil recovered was plant steam distillation 1.86wt% which was found to be high in comparison In this part of study, pulverized sandalwood to that of unpulverized sandalwood chips. It was also powder (2 mm size) was soaked in cold water for observed that pulverization exposed the sandalwood 48 h. It was then charged in the distillation still vessels and hence the oil recovery was improved. along with the water. Steam pressure was 0.7 bar α-santalene and β-santalene were 2.17 and 1.26% and α-santalol and β-santalol were 40.19 and 12.40% respectively. The reduced extraction of α-santalol and β-santalol could be because of these losses during pulverization. The colour of the oil was pale yellow and it had pleasant smell (refs 11,12). Hydro distilled sandalwood powder was then dried and charged for the solvent extraction using benzene. The extraction was carried for 5 hrs. The concrete obtained was 4.27% with dark red colour. The absolute obtained was 1.25% in which α-santalene, β-santalene and α-santalol, β-santalol were 3.42, 4.99, 38.21 and 22.96% respectively.
The net oil recovered was 3.11 wt% (refs 11,12). Fig. 1 ─ Chemical structure of major constituents of sandalwood oil 294 INDIAN J. CHEM. TECHNOL., JULY 2014
Table 2─Extraction of sandalwood oil Method of Batch time Physical/pre- % concrete % oil/absolute Major Colour of Odour of extraction h treatment extracted extracted constituents, % oil oil Section 1 Hydro 36 Whole sandalwood - 1.71 (i) traces (ii) traces Pale Pleasant distillation chips immersed in (iii) 48.38 (iv)28.73 yellow cold water for 24 h Solvent 5.15 After hydro distillation 5.53 0.37 (i) 0.36 (ii) 0.83 Pale Less extraction chips were finely (yellowish (iii) 39.71 (iv)19.76 yellow pleasant (toluene) pulverized. red concrete) Hydro 12 - - 1.05 (i) 3.98 (ii) 4.87 Pale Less distillation (iii) 38.47 (iv)20.42 yellow pleasant of concrete Hydro 30 Pulverized coarse - 1.86 (i) 2.17 (ii) 1.26 Pale pleasant distillation powder (iii) 40.19 (iv).42 yellow Soxhlet 10 Medium/coarse 7.56 2.59 (i) 3.98 (ii) 4.80 Pale Less Extraction pulverizing (iii) 29.22 (iv)30.54 yellow pleasant (toluene) Hydro 48 0.3%alkaline water, - 2.68 (i) 4.25 (ii) 3.01 Pale Pleasant Distillation coarse/medium (iii) 41.90 (iv)14.89 yellow pulverized Hydro 38 Ungrounded chips - 1.56 (i) 0.30 (ii) 0.91 Pale Pleasant distillation immersed in hot (iii) 56.73 (iv)27.10 yellow water for 24 h Section 2 Steam 10 Fine pulverized - 1.60 (i) 0.77 (ii) 1.80 Pale Pleasant distillation powder (iii) 54.74 (iv)29.58 yellow Soxhlet 3 Steam distilled 2.07 1.05 (i) 0.85 (ii) 1.70 Pale Pleasant Extraction powder (iii) 42.22 (iv)23.26 yellow (benzene) Soxhlet 6 Coarse pulverizing 10.90 3.70 (i) 0.96 (ii) 3.28 Pale Less Extraction immersed (iii) 50.03 (iv) 27.87 yellow pleasant (ethyl alcohol) Soxhlet 5 Coarse pulverizing 5.23 2.58 (i) 0.57 (ii) 1.47 Pale Less Extraction immersed (iii) 48.82 (iv) 14.89 yellow pleasant (diethyl ether) Soxhlet 5 Previously hydro 4.27 1.25 (i) 3.42 (ii) 4.99 Pale Pleasant Extraction distilled 30 hours (iii) 38.21 (iv) 23.37 yellow (benzene) coarse powder Soxhlet 12 Coarse pulverizing 4.98 2.45 (i) 3.84 (ii) 4.03 Pale Less Extraction immersed (iii) 37.04 (iv) 15.89 yellow pleasant (toluene) Soxhlet 5 Pulverized fine 6.25 3.01 (i) 7.79 (ii) 5.12 Pale Pleasant extraction powder (dark red) (iii) 30.54 (iv) 15.98 yellow (benzene) (i) α-santalene, (ii) β –santalene, (iii) α-santalol, (iv) β –santalol. gauge and the batch time was 10 h. About 8.1 g powder was extracted using benzene for 3 h, yielding oil was obtained from 500 g of sandalwood 2.07 wt% of the concrete. This was subjected to powder; the recovered oil being 1.62wt%. The oil hydro distillation for recovering 1.05wt% of the was pale yellow in colour with pleasant odour. absolute. Thus, total yield of the oil recovered In all six fractions were collected, each comprising was 2.67wt%. GC analysis of the solvent extracted 2 L of water. No oil was observed in the sixth oil showed 0.85% and 1.70% of α-santalene and fraction GC analysis of the oil showed 54.74 and β-santalene, whereas 42.22% and 23.26% of 29.58% of α-santalol and β-santalol. Steam distilled α-santalol and β-santalol respectively16,17. NAUTIYAL: PROCESS OPTIMIZATION OF SANDALWOOD OIL BY SC-CO2 295
Table 3─Comparison of extracts of sandalwood oil obtained by different processes Process of extraction Concrete extracted Absolute extracted Composition of oil wt% wt% % (i) (ii) (iii) (iv)
Liquid CO2 extraction (200 bars, 28°C, 4h) - 3.76 0.48 1.08 54.50 28.00 Solvent extraction Benzene (5h) 6.30 3.01 7.86 1.63 30.81 12.18 Diethyl ether (5h) 5.23 2.58 0.57 1.47 48.82 23.37 Ethyl alcohol (5h) 10.90 3.70 1.14 0.42 54.55 29.01 Hydro distillation (30h) - 1.86 2.17 1.26 40.19 12.40 Hydro distillation, alkaline treated (48h) - 2.68 4.25 3.01 41.90 14.89 Steam-distillation, pilot plant (10h) - 1.60 0.77 1.80 54.74 29.58 (i) α-santalene, (ii) β –santalene, (iii) α-santalol, (iv) β –santalol
Sandalwood oil obtained by different processes is However, the recovery of the solvent after extraction summarized in Table 3. The major constituents was poor. Diethyl ether is a non-polar solvent. α-santalol and β-santalol were extracted in good amount The per cent recovery of the concrete was 4.20, 4.33, by liquid carbon dioxide as well as by ethyl alcohol. 5.23 and 5.74% for 3, 4, 5 and 6 h extraction time. The per cent recovery of the absolute was 2.08, 2.14, Solvent extraction 2.58 and 2.60% for the same batch time of extraction. Effect of batch time on extraction of sandalwood oil using Although the recovery of the concrete at 6 h was ethyl alcohol more compared to that at 5, the recovery of an Extraction of sandalwood oil was carried out absolute at the same batch time was less than that of varying the batch time between 4 h to 7 h. 5 h. This may be due to extraction of waxes and not The extraction of the concrete was 6.67, 8.75, 10.90 the resins which contain oil18,19. and 10.91wt%. It was found that when ethyl alcohol was employed as a solvent the per cent recovery Effect of batch time on extraction of sandalwood oil using of the concrete was higher than that extracted by benzene benzene, toluene and diethyl ether. The absolute The composition of the sandalwood oil after 3 extraction was 2.45, 2.80, 3.70 and 3.73wt%. and 5 h batch time of extraction was analysed by The peak areas of α-santalene and β-santalene at GC. Peaks of α-santalene, β-santalene, α-santalol and 4 h were 1.12 and 1.75% and that of α-santalol and β-santalol were taken to represent the quality of β-santalol were 43.80 and 24.87% respectively. sandalwood oil. It was found that higher quantities The extraction of α-santalene and β-santalene at of α-santalol and β-santalol were obtained when batch 5 h were 0.96 and 3.28% and that of α-santalol time was increased from 3 h to 5 h. There was and β-santalol were 50.03 and 27.51% respectively. an increase in the α-santalene and β-santalene Similarly the peak areas of α-santalene and contents of the sandalwood oil. Sandalwood oil was β-santalene were 1.14 and 0.42% and that of also extracted using toluene for the batch time of 12 h. α-santalol and β-santalol were 54.55 and 29.01% The yield of the concrete was 4.98 wt% and that respectively at 6 h. The content of α-santalene and of the oil was 2.45 wt%18,19. β-santalene were 0.54 and 1.25% and that of α-santalol and β-santalol were 50.99 and 27.20% Extraction of sandalwood oil using Toluene respectively. Extraction of major constituents was 18,19 Sandalwood oil was extracted using Soxhlet better . apparatus with toluene as a solvent for a batch time
Effect of batch time on extraction of sandalwood oil using of 12 h. The yield of the concrete was 4.98wt% and diethyl ether the absolute obtained was 2.45wt%. The composition Major problem, using diethyl ether as an extractent, of α-santalen, β-sanatlene, α-santalol and β-santalol was its high volatility due to its low boiling point. were 3.98, 4.80, 29.22 and 12.58% respectively. The The loss during the extraction was minimized by odour was less pleasant as compared to the extraction circulating cold water at 10oC through the condenser. with benzene19,20. 296 INDIAN J. CHEM. TECHNOL., JULY 2014
Table 4 ─ Physical properties of sandalwood oil Method of extraction Pre treatment Refractive index Optical rotation Acid value Hydro distillation Whole chips 1.500 -22.97 Nil Soxhlet extraction Pulverized coarse 1.503 -19.14 4.67 (TOLUENE) size powder Hydro distillation of concrete Nil 1.499 Nil 7.33 Hydro distillation Pulverized coarse size powder 1.499 -14.46 5.58 Hydro distillation Pulverized coarse size powder, 1.502 -19.57 2.66 0.3% alkaline distilled water Steam distillation Pulverized powder immersed 1.503 -24.67 6.39 in cold water (48 hrs) Soxhlet extraction (ethanol) Fine pulverized powder 1.504 -19.56 7.79 Soxhlet extraction (diethyl ether) Fine pulverized powder 1.503 -14.46 7.79 Soxhlet extraction (benzene) Pulverized fine powder 1.502 -28.07 6.95 Soxhlet extraction (toluene) Pulverized coarse size powder, 1.501 Nil 6.71 immersed in hot water
Liquid CO2 extracted Fine pulverized powder 1.505 -22.97 4.10 Commercial sandalwood oil Nil .504 -19.57 4.15 Required specification : Refractive index 1.499-1.506, Acid value 0.5-8, and Optical rotation 15° to -19.20°.
Comparison of the sandalwood oil obtained by different techniques, being used in the recovery of the separation methods solubilised constituents may add up to the yield, it A comparison of extracts of sandalwood oil, also adds cost and time of processing. Moisture obtained by different methods, has shown that minimization in sandalwood oil is quite essential so as the major constituents α-santalol and β-santalol were to maintain its quality and shelf life. Solvents usually extracted in good amount by liquid carbon dioxide extracts concrete first and then recovery of an as well as by ethyl alcohol. absolute is made through alcohol selectively. But here The physical properties of the sandalwood oil, such also the yield and quality may be down due to multi as refractive index, optical rotation and acid values, processing techniques. are presented in Table 4. The optical rotation value obtained by hydro distillation, steam-distillation, Hydro distillation yields 1.86wt% of oil in 30 h. benzene extraction and liquid carbon dioxide extraction The yield of oil is found to increase when the were not within the required specification. However, particle size is reduced. Pulverized sandalwood yields the refractive index and the acid value for all the 2.68wt% of oil in 48 h when alkaline water is used experiments were within the stipulated values for for hydro distillation. The yield as well as the colour sandalwood oil21-23. of the oil is found to be better when alkaline water is used for hydro distillation. When fine pulverized powder is charged for steam distillation using Conclusion steam pressure of 10 psi, the yield obtained by steam It is evident from the results that the extraction distillation is 1.60wt%. of sandalwood oil with subcritical state CO2 at 200 bars and 28oC yield 4.11wt% of sandalwood The best yields of absolute (3.70wt %) and oil in 1 h of batch time with maximum isolation concrete (10.90wt %) are obtained when ethyl alcohol of major constituents - the price deciding factors is used as solvent. The major constituents of the of the oil. Though the conventional techniques oil, viz. α-santalol and β-santalol are found 54.55 (steam distillation and hydro distillation) are being and 29.01% respectively. On the scale, the assigned practiced commercially, but produces low yield of score is 9.5 for the best quality of sandalwood oil oil and inferior quality due to lesser santalol and extracted by subcritical carbon dioxide. santalene contents. This is because these processes Physical properties of subcritical extracted take longer extraction time, and the major constituents sandalwood oil are found to be superior to that of are lost in distilled water. Though the cohobation conventional processing. NAUTIYAL: PROCESS OPTIMIZATION OF SANDALWOOD OIL BY SC-CO2 297
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