Deterpenation Process Research Articles

Seed Oil Extraction of Cucurbita maxima Duchesne Growing in Madagascar: Impact of Storage and Use of a Cineole–Rich Essential Oil as a Green Solvent

The performance of a cineole-rich essential oil as an extraction solvent for vegetable oil was studied. This essential oil was obtained from Melaleuca quinquenervia (Cav.) St Blake Myrtaceae, commonly called niaouli, an invasive plant on the eastern coast of Madagascar. The whole essential oil was used without preliminary isolation of terpenes. Experimentation was carried out with Cucurbita maxima Duchesne Cucurbitaceae seeds. The Soxhlet method was used for the oil extraction, and solvent recovery was performed by hydrodistillation. Niaouli essential oil allowed a better extraction yield of 39% compared to hexane, with 36%. The linoleic acid content of the oil was also higher: 37.19% against 7.25% for hexane. After 30 weeks of storage, the seed powder linoleic acid content increased to 44.99% for niaouli oil against 25.00% for hexane oil. With the screw press extraction method, the best yield of 13.00% was obtained with roasting pretreatment while heating at 60°C. However, the best oleic acid content of 45.36% was obtained at 50°C. It was demonstrated that the seed powder underwent biochemical changes during storage which were similar to intracellular catabolic reactions of fatty acids. The high expenses induced by the deterpenation process in terms of cost and energy limit the diffusion and the development of the use of terpenes as alternative solvents. The results of this research support the idea that it is possible to avoid this costly step by directly using the entire essential oil since this can provide a vegetable oil of good quality.

Transformer-convolutional neural network for surface charge density profile prediction: Enabling high-throughput solvent screening with COSMO-SAC

A deep learning (DL) method for quickly predicting surface charge density profiles (σ-profile) and cavity volumes (VCOSMO) of molecules for the COSMO-SAC model is developed. The molecular fingerprints are derived from the encoder state of a Transformer model pre-trained on the ChEMBL database, which allows transfer learning from large-scale unlabeled data and improve generalization performance by developing better molecular fingerprints for building models with significantly smaller datasets. Employing the pre-trained molecular fingerprints, a convolutional neural network (CNN) model for the σ-profile and VCOSMO prediction is trained and tested on the VT-2005 database. The obtained Transformer-CNN model presents superior performance to the GC-COSMO approach and enables the prediction of σ-profile and VCOSMO of millions of molecules in only a few minutes. Taking advantages of the model, a high-throughput solvent screening framework based on COSMO-SAC is further proposed and exemplified by searching sustainable solvent for the deterpenation process of citrus essential oils.

RESTRAIN HYPERCHOLESTEROLEMIA WITH ORANGE AND MANDARIN VOLATILE AND FOLDED OILS

ABSTRACT The findings of this study proved that orange peels contain more twice oil yield over mandarin peels (0.24% and 0.12%, respectively). Concentrated orange and mandarin peel essential oils were obtained by fractional distillation. The chemical constituents of original orange and mandarin oils (OO and MO) and their fivefold (5FOO and 5FMO) were fractionated and identified by GC/MS and GC. Limonene was the major monoterpene component in orange and mandarin oils, 89.65% and 65.57%, respectively, followed by myrcene (3.95%) and γ-terpinene (23.07%) in orange and mandarin oils, respectively. Octanal (1.47%) and linalool (1.5%) were the abundant oxygenated components in orange and mandarin oils, respectively. The decrement percentages of limonene were 18.58 and19.25% in five fold orange and mandarin oils, respectively. The major oxygenated component in 5FOO was the alcoholic β- Cis-terpeneol (4.27%). The main esters of mandarin oil, methyl N-methyl anthranilate and geranyl acetate were increased to 0.45% and 1.05%, respectively in 5FMO. In general, total oxygenated compounds percentages increased by 6.9 and7.3 times after folding of orange and mandarin oils, respectively. The above mentioned oils, pure limonene and synthetic antioxidant (BHT) were orally administrated for hypercholesterolemic rats for four weeks. No significant differences were recorded among groups of rats administrated with all different tested oils in body weight gain (%) or feed intake (g) (p≤ 0.05). In general, all rat groups administrated with orange and mandarin oils and their concentrates, showed improvement in HDL levels nearly to normal level compared to the negative control. Thus, the decrement of serum cholesterol level among cholesterol-fed groups did not correlate with the amount of limonene consumed by rats and may be related to other minor components associated with limonene and shared in the antioxidant effect. The efficiency of folded oils on hypocholesterolemic rats did not affect by decreasing limonene by deterpenation process.

Deterpenation of Citrus Essential Oils Using Glycerol-Based Deep Eutectic Solvents

Citrus essential oils are complex hydrocarbon mixtures mainly composed of terpenes and terpenoids and are widely used as raw materials in food, pharmaceutical, and fine chemical industries. However, essential oil deterpenation (i.e., separation of terpenes and terpenoids) is required to preserve the quality of the final product for practical applications. Currently, there is a need to find efficient and environmentally friendly solvents to replace the harmful volatile organic compounds that are conventionally used as extraction solvents. Therefore, alternative solvents with more benign and environmentally friendly characteristics are crucial to develop sustainable citrus essential oil deterpenation processes. In this work, biorenewable deep eutectic solvents (DES) composed of glycerol (Gly) and choline chloride (ChCl) are evaluated as sustainable solvents for citrus essential oil deterpenation, using model mixtures and real citrus crude orange essential oils (COEO). The liquid–liquid extraction process fo...

Deterpenation of Origanum majorana L. essential oil by reduced pressure steam distillation

The present work is focusing on the technical viability of the reduced pressure steam distillation to perform the deterpenation of the Origanum majorana L. essential oil (EO), and the evaluation of antioxidant and antifungal activities. The EO and the obtained fractions (F1, F2 and F3) were characterized by GC/MS and FT-IR. The result showed that, the chemotype of the EO was terpin-4-ol (27.32%), γ-terpinene (15.67%) and α-terpinene (11.08%). However, during the deterpenation process the chemotype changed for F1 to γ-terpinene (27.53%), α-terpinene (21.15%) and sabinene (11.17%), for F2 to terpin-4-ol (54.39%) and cis-sabinen hydrate (10%) and for F3 to terpin-4-ol (48.6%) and β-fenchyl alcohol (23.84%). Moreover, the free radical scavenging method showing that the EO and its fractions did not present a strong antioxidant capacity. Regarding the antifungal activity, an experimental design with different methods was applied. Particularly, the deterpenated fractions showed the highest activity against Aspergillus niger with 100% and 85.09% of inhibition using the F2 and F3 respectively. However, the raw EO and the F1 presented the lowest antifungal activity with 36.56% and 8.76% of inhibition, respectively. In conclusion, this work demonstrates that reduced pressure steam distillation was an effective method to perform the fractionation of the raw EO from Origanum majorana L. Particularly, deterpenated fractions possess an interesting antifungal activity highlighting their possible uses in biotechnological fields and/or pharmaceutical industry.

(Liquid + liquid) equilibrium for systems composed of clove and allspice essential oil compounds and hydrous ethanol at T = 298.2 K

In the deterpenation process of essential oils, a fraction enriched in oxyterpenes is obtained. When compared to terpenic hydrocarbons, this fraction is more stable and soluble in water, maintaining the characteristic flavor and fragrance of the crude oil. Solvent extraction is an interestingly popular technique that is proposed for the fractionation of essential oils (once it can be performed under atmospheric pressure and ambient temperature) and contributes to the maintenance of the sensory quality of essential oils. The use of hydrous ethanol as a solvent for the (liquid+liquid) extraction process has shown advantages when the components of interest are completely soluble in ethanol, and their partition can be adjusted based on the level of hydration of the solvent. In addition, for some purposes, the fractions obtained from the separation process can be used without removing the solvent. Therefore, the primary goal of this study was to investigate the (liquid+liquid) equilibrium at T=(298.2±0.1)K of model systems composed of (caryophyllene+eugenol+ethanol+water) (i.e., a clove essential oil model system) and (caryophyllene+methyl eugenol+eugenol+ethanol+water) (i.e., an allspice essential oil model system) to provide the information required for the proper design and optimization of the associated deterpenation processes. For both systems studied, it was noted that increased water content in the solvent decreases the extraction of the essential compounds and increases the selectivity of the solvent. Oxygenated compounds (e.g., methyl eugenol and eugenol) showed greater affinity for the solvent when compared to the sesquiterpenic hydrocarbon (e.g., caryophyllene). The experimental values were correlated using the NRTL thermodynamic model, which provided a satisfactory performance and low deviations in the phase composition descriptions with global deviations near 0.0050 (mass fraction).

Phase equilibrium data for systems composed of oregano essential oil compounds and hydroalcoholic solvents at T = 298.2 K

The deterpenation process of essential oils consists of terpene removal and a consequent concentration of oxygenated compounds, which increases the sensorial quality, the aromatic potential and the oxidative stability of the oil. Deterpenation of oregano (Origanum vulgare L., Lamiaceae) essential oil, which has been used extensively as a popular medication and as an antimicrobial, antifungal, antimutagenic and a powerful antioxidant agent, can be performed by (liquid+liquid) extraction using hydroalcoholic solvents. This research presents (liquid+liquid) equilibrium data for model systems composed of p-cymene, thymol, terpinen-4-ol and α-terpineol, some of the main components of oregano essential oil, using hydrous ethanol as the solvent with the water mass fraction ranging from 0.28 to 0.41 at T=(298.2±0.1)K. The results show that an increase in the hydration of the alcoholic solvent causes a negative influence on the values of the distribution coefficient for the three oxygenated compounds (thymol, terpinen-4-ol and α-terpineol), with an increase in solvent selectivity. An increase in the content of oxygenated compounds in the terpene-rich phase reduces their distribution coefficients and the selectivity values. In addition, binary interaction parameters were estimated correlating the experimental data using the NRTL and UNIQUAC thermodynamic models, and the global deviations were lower than 0.0060 for all systems, indicating that both molecular models show a good descriptive performance.

Conversion of Limonene into More Valuable Aroma under Hydrothermal Conditions

The aromatic components in citrus essential oils are monoterpenes, sesquiterpenes, and some oxygenated compounds. It is known that monoterpenes, such as limonene, take a little part of the aroma and are sometimes removed by deterpenation processes. In this study, a novel technology through a wet oxidation process using hydrogen peroxide was investigated for the conversion of limonene. Experiments were conducted using a batch type reactor to study the effects of temperature and reaction time on the conversion of limonene under the following conditions: temperature range of 150 to 200C at reaction time of 10-80 min. After each run, samples consisting of 2 layers (oil and water phases) were collected. The oil layer was qualitatively analyzed of its composition using a gas chromatography-mass spectrometry (GC-MS) apparatus, while the organic carbon content in water layer was analyzed using a total organic carbon (TOC) analyzer. Results obtained under these conditions indicated highly selective conversion of limonene especially into its isomers.

Improved concentration of citrus essential oil by solvent extraction with acetate ionic liquids

Citrus essential oils have numerous applications in multiple sectors, including food, drink and personal care industries. Although mainly constituted by terpenes, the appealing characteristics of citrus essential oils are due to oxyterpenes and other derived oxygenated compounds. In fact, the presence of terpenes in the essential oil may lead to instability or loss of quality. Therefore, concentration of the oil in its oxyterpene compounds by removal of terpenes is desirable. The techniques currently in use for deterpenation of essential oils present a series of issues. In the search for better deterpenation processes, here the use of ionic liquids as solvents in liquid–liquid extraction is explored. In particular, the ionic liquids 1-ethyl-3-methylimidazolium acetate and 1-butyl-3-methylimidazolium acetate are investigated for their extraction of oxyterpene from a modelled citrus essential oil composed of limonene (terpene) and linalool (oxyterpene). The choice of the ionic liquids, in addition to other complementary characteristics, was based on a rationale of potential interactions that can be created preferentially with the linalool. The results show a great performance of these acetate-based ionic liquids, as compared to any other ionic or molecular solvent tested to date, for the concentration in oxyterpenes of the citrus essential oil.

Deterpenation of eucalyptus essential oil by liquid + liquid extraction: Phase equilibrium and physical properties for model systems at T = 298.2 K

As the principal source in Brazil of eucalyptus essential oil extracts, Eucalyptus citriodora contains citronellal, an oxygenated compound responsible for the flavour characteristics. Deterpenation processes, consisting of the removal of terpenic hydrocarbons with the subsequent concentration of the oxygenated compounds, can be used to improve the aromatic characteristics of this essential oil. The purpose of this work was to perform a study of the technical feasibility of using a liquid+liquid extraction process to deterpenate eucalyptus essential oil. Model systems with various mixtures of limonene and citronellal (representing eucalyptus essential oil) as well as solvent (ethanol with various water mass fractions) were used to obtain liquid+liquid equilibrium data. The raffinate and extract phases were also analyzed to characterize the physical properties (density and viscosity). The equilibrium data were used to adjust the NRTL and UNIQUAC parameters. Two empirical models, the simple mixing rule and the Grunberg–Nissan model, were evaluated for use in the descriptions of the densities and viscosities, respectively, of the samples. Increasing the water content in the solvent resulted in decreases in the limonene and citronellal distribution coefficients, with consequential increases in the solvent selectivity values. Increasing values of the densities and viscosities, especially for the solvent-rich phases, were associated with systems using high amounts of hydrated ethanolic solvents.

High-pressure gas–liquid equilibrium of the system carbon dioxide–citral at 50 and 70 °C

Measurements of high-pressure gas–liquid equilibria of the binary system carbon dioxide–citral were carried out in the present work. The knowledge of the phase equilibrium behaviour of this system is relevant with regard to the design and optimization of the supercritical deterpenation process. The measurements were carried out at 50 and 70 °C, in the pressure range 7.8–15.6 MPa, by means of a two-chamber gas-phase recirculation apparatus of 340 cm 3. Both the liquid and the gas phase composition were measured. The data at 50 °C measured in this work were compared with literature data, whereas no comparison was possible at 70 °C because of their lack. The experimental data measured in this work were successfully correlated by means of a thermodynamic model based on the Peng–Robinson equation of state.

Carotenoid Extraction from Tomato Using a Green Solvent Resulting from Orange Processing Waste

Here is described a useful and green method for the extraction of lycopene using d-limonene (bio-solvent) a substitute for dichloromethane (petroleum solvent). The described method was achieved in two steps: at first, limonene was obtained from the orange peel through a steam distillation procedure followed by a deterpenation process, in second step, lycopene was extracted using d-limonene as a solvent, instead of dichloromethane. Lycopene extracted from tomato fruit were compared with both conventional petroleum and bio-solvent in terms of qualitative and quantitative determination. No significant difference was obtained between each extracts allowing us to conclude that the proposed method is effective and valuable.

Continuous countercurrent deterpenation of lemon essential oil by means of supercritical carbon dioxide: Experimental data and process modelling

A thermodynamic model based on the Peng–Robinson equation of state was developed in order to perform high-pressure phase equilibria calculations for the system carbon dioxide–lemon essential oil. The multicomponent natural oil was simulated by a mixture of three key components, one for each relevant class of compounds (monoterpenes, monoterpene oxygenated derivatives and sesquiterpenes). Firstly the proposed model was validated on semi-batch experimental data and then it was used to simulate the behaviour of a continuously operated countercurrent column. Experiments on deterpenation process on a packed column, operating as a stripping section, were carried out in the temperature range 50–70 °C and pressure range 8.7–11.2 MPa. The comparison between experimental results and process simulation demonstrated that the proposed model is capable of reliable predictions on the behaviour of the countercurrent continuous deterpenation process. Furthermore, an average height equivalent to a theoretical plate of about 40 cm was estimated, for the stated packing and operating conditions. A case study for the production of 10-fold high quality oil, with strict specifications for the recovery of oxygenated compounds (99%), was investigated by simulations of a continuous countercurrent process with an external reflux. The linkage between the number of theoretical stages, the reflux ratio and the solvent to feed ratio was investigated throughout the above-mentioned pressure and temperature ranges. Operating conditions at higher pressure and temperature proved to be more favourable. As an example, operating a 20 theoretical stage column at 70 °C and 11.2 MPa, it is possible to attain process specifications with a solvent to feed ratio of about 63.

Excess molar enthalpies for mixtures of supercritical CO 2 and linalool

Excess molar enthalpies ( H m E ) for mixtures of supercritical CO 2 and linalool were measured at conditions of temperature and pressure typical of supercritical extraction processes: 313.15 and 323.15 K and 7.64, 10.00 and 12.00 MPa. The measurements were carried out using an isothermal high-pressure flow calorimeter. The effects of pressure and temperature on the excess molar enthalpy are large. Mixtures formed by low-density carbon dioxide and linalool show very exothermic mixing and excess molar enthalpies exhibit a minimum in the CO 2-rich region. The lowest H m E values (≈−4000 J mol −1) are observed for mixtures at 313.15 K and 7.64 MPa. Mixtures formed by high-density carbon dioxide and linalool show considerably endothermic mixing (≈400–600 J mol −1) in the linalool-rich region and moderately exothermic mixing for the other compositions. On the other hand, H m E at 7.64 MPa and 313.15 and 323.15 K varies linearly with CO 2 mole fraction in the two-phase region where a gaseous mixture and a liquid mixture of fixed composition, for a given condition of temperature and pressure, are in equilibrium. Results are analyzed in terms of phase equilibria, pure carbon dioxide density and CO 2–terpene molecular interactions. Excess molar enthalpies are simultaneously correlated using the Soave–Redlich–Kwong and Peng–Robinson equations of state and the classical mixing rule. The significance of these large variations of H m E with temperature and pressure in the design of supercritical fluid deterpenation processes is discussed.

Citrus peel oil deterpenation with supercritical fluids: Optimal process and solvent cycle design

In this work supercritical deterpenation of orange peel oil with carbon dioxide is studied. Optimal schemes and operating conditions are determined through the formulation of a nonlinear programming model that includes reliable thermodynamic predictions with a group contribution equation of state and rigorous unit models. A detailed comparison of binary and ternary equilibrium predictions with available experimental data is reported. Simulation results are in agreement with previous laboratory-scale separation values. Different solvent cycle schemes have been included in the mathematical model. Net profit is maximized taking into account capital and operating costs associated to the complete deterpenation process. Numerical results show that a compression cycle is the optimal solvent recovery system in all cases. Furthermore, optimal operating conditions have been determined in main units (extractor and separator), for the production of both a five-fold concentrate and a high purity aroma, as raffinate, respectively.

Semi-batch packed-column deterpenation of origanum oil by dense carbon dioxide

The study aims at the separation of the undesired, light monoterpenes (MTs) of origanum oil from more valuable and heavier non-monoterpenes (NMTs). The scope of this work is the analysis of fundamental aspects of semi-batch, packed-column deterpenation process of origanum oil by dense CO 2 at 70/85 bar pressure and 38/55°C temperature levels. Effects of operating pressure, temperature zones, presence of packing, and entrainer (ethanol) use are investigated. GC/MS analyses of 14 major components constituting the bulk (86.4%) of the oil samples obtained from the top of the packed column in four different deterpenation time-cuts show that the resulting deterpenated product is rich in MTs (48–89% MTs, 52–11% NMTs). The oil remaining in the extraction vessel is rich in high-molecular-weight NMTs (15–24% MTs, 85–76% NMTs). Thus, the quality of origanum oil is improved as compared to the oil charged (36.44% MTs, 63.56% NMTs). Separation deteriorates with increasing deterpenation time. Enhancement of separation with packing is observed at the first time-cut. No significant entrainer effect (1.25, 2.5, and 5% ethanol in the charge) is noticed. Statistical analyses of the data and a response-surface analysis based on empirical models are presented. Suggested processing scheme that employs selective CO 2 extraction and rectification has the potential for use in essential-oil refining technology.