Pressurized Liquid Extraction Process Research Articles

Alternative green extraction techniques to enhance recovery of antioxidant compounds from red peel prickly pear (Opuntia ficus-indica L. Miller)

Prickly pear (Opuntia ficus-indica L. Miller) is a natural source of antioxidant compounds that have gained significant attention due to their potential health benefits. This study aims to investigate the effectiveness of pressurized liquid extraction (PLE) and Ultrasound-Assisted Extraction (UAE), combined with water–ethanol mixtures from 0 to 60%, at moderate temperatures between 50 °C to 70 °C to improve the recovery of antioxidant compounds from red peel prickly pear. The recovery of these compounds was affected by solvent composition and temperature for both extraction techniques. Interestingly, the use of pure water at 70 °C during the PLE process allowed the recovery of high concentrations of antioxidant compounds (12.96 mg GAE/g dw, IC5O: 2.03 mg/mL, ORAC: 625 µmol TE/g dw). On the contrary, when the UAE process was combined with 30% ethanol at 50 °C, the extractability of these compounds (10.52 mg GAE/g dw, IC5O: 3.09 mg/mL, ORAC: 561.26 µmol TE/g dw) was improved. In addition, different solvent compositions were identified to improve the recovery of specific polyphenols. For PLE, pure water at 70 °C was effective in recovering phenolic acids, flavanols, and flavonols, while the highest concentrations of stilbenes were obtained with 60% ethanol at 70 °C. For UAE, the use of 30% ethanol at 50 °C was more effective in extracting phenolic acids and stilbenes, whereas pure water at 50 °C provided high concentrations of flavanols and flavonols. These results contribute to the development of sustainable and efficient extraction strategies for obtaining antioxidant-rich extracts from prickly pear peel with important applications in functional foods, nutraceuticals, and pharmaceutical industries.

Exploring a Sustainable Process for Polyphenol Extraction from Olive Leaves.

Olive leaves are residues from pruning and harvesting and are considered an environmental management problems. Interestingly, these residues contain high polyphenol concentrations, which can be used to treat chronic diseases. However, these compounds are a technological challenge due to their thermolability and reactivity during extraction. Thus, this study assessed the use of pressurized liquid extraction (PLE) with green solvents like water-ethanol and water-glycerol mixtures (0-15%) at 50 °C and 70 °C to yield polyphenol-rich antioxidant extracts with reduced glucose and fructose content. The use of 30% ethanol at 70°C presented the highest polyphenol content (15.29 mg gallic acid equivalent/g dry weight) and antioxidant capacity, which was expressed as IC50 (half maximal inhibitory concentration): 5.49 mg/mL and oxygen radical absorbance capacity (ORAC): 1259 μmol Trolox equivalent/g dry weight, as well as lower sugar content (glucose: 3.75 mg/g dry weight, fructose: 5.68 mg/g dry weight) compared to water-glycerol mixtures. Interestingly, ethanol exhibits a higher degree of effectiveness in recovering flavanols, stilbenes and secoiridoids, while glycerol improves the extraction of phenolic acids and flavonols. Therefore, to enhance the efficiency of polyphenol recovery during the PLE process, it is necessary to consider its solvent composition and chemical structure.

Pressurized liquid extraction and gas chromatography/mass spectrometry for determination of nitrated polycyclic aromatic hydrocarbons adsorbed on refractory diesel particles

A pressurized liquid extraction (PLE) technique was evaluated in this study and optimized using response surface methodology (RSM) for the determination of polycyclic aromatic hydrocarbons and their nitro derivatives from diesel particulate matter. A central composite design (CCD) was applied for the study of three parameters (temperature, nature of solvent and static time) and the optimal conditions were determined for a time of 9 min and a temperature of 145 °C and dichloromethane as extraction solvent. With the GC/MS analytical technique, the limits of detection (LOD) obtained range from 0.3 to 1.5 µg.L-1 for PAHs and from 4.6 to 8 µg.L-1 for nitrated PAHs. Also, this method allowed excellent recoveries of NPAH adsorbed on diesel soot particles (R ≥ 90%) using a mixture of solvents (1% acetic acid in pyridine). The PLE process developed in this research is quantitative and reproducible while using much less solvent than conventional extraction methods.

Pressurized liquid extraction as an eco-friendly approach to recover anthocyanin from black rice bran

This study aimed to recover the anthocyanin-rich extract from black rice bran by pressurized liquid extraction (PLE) and compare with the conventional process (heating-stirring extraction - HSE). PLE performs fast and efficiently and results in high yields in less time and less solvent, being considered eco-friendly. The extracts were characterized for thermal and light stabilities, cytotoxicity, antitumoral activity, and cytoprotective effect. Optimum PLE conditions were: 55 °C, a flow rate of 5 mL/min, and solution ethanol:citric acid 0.1 mol/L (50:50, v/v). PLE recovered about 80% of total anthocyanins (2.33 mg/C3GE g), while HSE recovered 46% (1.17 mg/C3GE g). Cyanidin-3-O-glucoside (C3G) was identified (m/z 449) and quantified, 1.63 mg/g for PLE and 1.07 mg/g for HSE. Both anthocyanin-rich extracts in low temperature showed high thermostability, did not present cytotoxicity (normal fibroblast L929 cells), and showed cytoprotection of L929 cells when subjected to oxidative stress with H2O2. Overall, the anthocyanin-rich extracts obtained by PLE showed potential to be applied as natural colorants and possibly to improve wound healing. Industrial relevancePLE method is an eco-friendly technology that performs fast and efficient extractions under high temperature and pressure conditions. This study provides information about the extraction of anthocyanin-rich extracts from black rice bran by green PLE process under optimized conditions. The process allowed for obtaining antioxidant-rich extracts with no cytotoxicity and a high potential for application in the food, cosmetic, and biomedical industries.

Isolation of Garlic Bioactives by Pressurized Liquid and Subcritical Water Extraction

Garlic (Allium sativum L.) is widely used in various food products and traditional medicine. Besides unique taste and flavour, it is well known for its chemical profile and bioactive potential. The aim of this study was to apply subcritical water extraction (SWE) and pressurized liquid extraction (PLE) for the extraction of bioactive compounds from the Ranco genotype of garlic. Moreover, PLE process was optimized using response surface methodology (RSM) in order to determine effects and optimize ethanol concentration (45-75%), number of cycles (1-3), extraction time (1-3 min) and temperature (70-110 °C) for maximized total phenols content (TP) and antioxidant activity evaluated by various in vitro assays. Furthermore, temperature effect in SWE process on all responses was evaluated, while allicin content (AC), as a major organosulphur compound, was determined in all samples. Results indicated that PLE provided tremendous advantage over SWE in terms of improved yield and antioxidant activity of garlic extracts. Therefore, high-pressure processes could be used as clean and green procedures for the isolation of garlic bioactives.

Pressurized green liquid extraction of betalains and phenolic compounds from Opuntia stricta var. Dillenii whole fruit: Process optimization and biological activities of green extracts

The Opuntia Stricta var. Dillenii's prickly pears are an underutilized fruits, which provide a great source of betalains (mainly, betacyanins) and phenolic compounds (phenolic acids and flavonoids) that could play an important role in health-promotion. This study focuses on the optimization of process for the green extraction of betalains and phenolic compounds from Opuntia stricta var. Dillenii's whole fruits by Pressurized liquid extraction (PLE), using a response surface methodology (RSM) by a central composite design (CCD) in order to obtain rich extracts in betalains and phenolic compounds with the similar profile of the original one found in O. dillenii fruits (avoiding any degradation of these compounds during the extraction process) with proven biological activities. For PLE optimization, the ethanol volume in water (0–100%, v/v) and the temperature (25–65°C) were selected as independent variables. The identification and quantification of the individual bioactive compounds of the obtained green extracts were done by HPLC-DAD-ESI/MS and HPLC-DAD-ESI/QTOF and their biological activities were determined by in vitro tests, as: the antioxidant activity by the ORAC method and the anti-inflammatory activity by the hyaluronidase inhibition method. Ethanol volume in water (%, v/v) was the variable with most significant (p ≤ 0.05) effect in the target responses (bioactive content and biological activities). The best results were obtained at 50% ethanol in water (v/v) and 25°C temperature (run 10) obtaining extracts with betalains as 2.34 ± 0.18 mg of betanin/g dry weight, 2.51 ± 0.04 mg of 5′´-O-E-sinapoyl-2′-apyosil-phyllocactin/g dry weight, 2.32 ± 0.19 mg of neobetanin/g dry weight and phenolic compounds, 2.08 ± 0.07 mg of piscicid acid/g dry weight and 0.25 ± 0.02 mg of isorhamnetin glucoxyl-rhamnosyl-pentoside (IG2) /g dry weight. The betalain and phenolic profile of the PLE extracts was quite similar to the profile from the conventional extraction, but PLE extraction process enhanced the extraction of some bioactives as neobetanin (39%) andpiscidic acid (124%). All employed PLE process CCD combinations significantly upgrade the in vitro biological activities (antioxidant and anti-inflammatory) of the Opuntia stricta var. Dillenii's PLE green extracts.

Pulsed electric fields (PEF), pressurized liquid extraction (PLE) and combined PEF + PLE process evaluation: Effects on Spirulina microstructure, biomolecules recovery and Triple TOF-LC-MS-MS polyphenol composition

This study aims at evaluating the impact of different processes-pulsed electric fields (PEF), pressurized liquid extraction (PLE) and a multistep process combining PEF + PLE on the yield of antioxidant compounds (protein, polyphenols, chlorophyll a, chlorophyll b, and carotenoids) from Spirulina. Firstly, the effects of PEF or PLE treatment on the extraction yield of Spirulina biomolecules were evaluated. To further increase the extraction yield, PEF + PLE was used, as an innovative extraction approach. The results showed that PEF + PLE greatly improved the extraction yield compared with the PEF or PLE treatments alone. Compared with Folch extraction (conventional control technique), PEF + PLE significantly (P < 0.05) shortened the extraction time (−165 min) and increased the protein, polyphenol, chlorophyll a and antioxidant capacity values of Spirulina extracts by 1328%, 979%, 11% and 47% respectively. Furthermore, Triple TOF-LC-MS-MS results showed that PEF + PLE increased both the type and content of phenolic compounds. The above results were attributed to PEF-induced damage on Spirulina helical structure, which was verified by fluorescence and scanning electron microscopy.

Recovery of Bioactive Compounds from Pomegranate (Punica granatum L.) Peel Using Pressurized Liquid Extraction.

Pressurized liquid extraction (PLE) is a clean and environmentally friendly alternative for the recovery of bioactive compounds from fruit by-products. Herein we focused on PLE for the extraction of bioactive compounds from pomegranate peel using a combination of pressurized water and ethanol. The main aim was to determine the optimal PLE conditions, i.e., ethanol percentage and process temperature, to obtain a pomegranate peel extract (PPE) with maximum total phenolic content (TPC), punicalagin content, and antimicrobial activity (AMA). The experimental design was conducted using a central composite design with axial points. Response surface methodology was applied to optimize the response variables using the desirability function. Multiple response optimization indicated a process temperature of 200 °C and ethanol of 77% as optimal conditions. The TPC and the punicalagin content of PPE-PLE obtained under optimal conditions were 164.3 ± 10.7 mg GAE/g DW and 17 ± 3.6 mg/g DW, respectively. Our findings support the efficacy of PLE on TPC recovery but not in punicalagin recovery. The AMA against S. aureus was 14 mm. The efficacy of PPE-PLE in food applications must continue to be studied in order to achieve adequate information on its potential for developing new food additives.

An eco-friendly pressure liquid extraction method to recover anthocyanins from broken black bean hulls

This study aimed to recover the anthocyanin-rich extract from broken black bean hulls by pressurized liquid extraction (PLE) and to study their chemical stability, inhibition capacity toward carbohydrate-enzymes and application in gelatin. A Box-Behnken design (BBD) coupled to response surface methodology (RSM) was applied in order to maximize the anthocyanin extraction conditions. Optimum PLE conditions obtained were ethanol:citric acid solution 0.1 mol L−1 (30:70, v/v), a flow rate of 4 mL min−1, and 60 °C. Delphinidin-3-glucoside was the main anthocyanin quantified. The PLE crude and purified anthocyanin-rich extracts inhibited α-amylase (IC50: 0.52 and 2.85 mg mL−1) and α-glucosidase (0.03 and 0.15 mg mL−1) enzymes, respectively. The PLE anthocyanin-rich extracts showed higher stability in low temperatures and in the absence of light. Besides, the application in gelatin provided a natural color and supplementation with antioxidant compounds. Overall, anthocyanin-rich extract obtained from black bean by-product using an eco-friendly PLE method shows potential as natural colorant and supplement. Industrial relevancePLE method is an emerging technique that performs fast and efficient extractions under high temperature and pressure conditions. The association of green technologies with green solvents makes PLE an eco-friendly technology. This article provides information about the extraction of anthocyanin-rich extracts from the broken black bean hulls by green PLE process under optimized conditions. The process allowed to obtain antioxidant-rich extracts with high application potential in food, supplements, and pharmaceutical industries.

Scale-up simulation of PLE process applied to recover bio-based materials from Sida rhombifolia leaves

Large-scale pressurized liquid extraction (PLE) data are scarce in literature, exposing the lack of information to support industrial projects. In this study, using Sida rhombifolia, the Sovová's model, developed for supercritical fluid extraction (SFE), was applied to describe PLE process, demonstrating good representation of experimental PLE data. A computational code, MatLab Simulation Extraction Models (MSEM), developed for SFE, was adapted to represent PLE mass transfer phenomena, and was able to adequately represent PLE in small and large scales. The performance was evaluated by process yield and extract quality (total phenolic content and antioxidant activity), and the results compared to Soxhlet method. The scale-up criteria consisted of constant geometric and mass transfer parameters between scales, provided statistically equivalent data. The results suggest a large-scale industrial application of a low environmental impact method, with reduced costs and high recovery of bio-based extracts, for application as ingredient for food, medicine or packaging material.

Comparison between Pressurized Liquid Extraction and Conventional Soxhlet Extraction for Rosemary Antioxidants, Yield, Composition, and Environmental Footprint.

Nowadays, “green analytical chemistry” challenges are to develop techniques which reduce the environmental impact not only in term of analysis but also in the sample preparation step. Within this objective, pressurized liquid extraction (PLE) was investigated to determine the initial composition of key antioxidants contained in rosemary leaves: Rosmarinic acid (RA), carnosic acid (CA), and carnosol (CO). An experimental design was applied to identify an optimized PLE set of extraction parameters: A temperature of 183 °C, a pressure of 130 bar, and an extraction duration of 3 min enabled recovering rosemary antioxidants. PLE was further compared to conventional Soxhlet extraction (CSE) in term of global processing time, energy used, solvent recovery, raw material used, accuracy, reproducibility, and robustness to extract quantitatively RA, CA, and CO from rosemary leaves. A statistical comparison of the two extraction procedure (PLE and CSE) was achieved and showed no significant difference between the two procedures in terms of RA, CA, and CO extraction. To complete the study showing that the use of PLE is an advantageous alternative to CSE, the eco-footprint of the PLE process was evaluated. Results demonstrate that it is a rapid, clean, and environmentally friendly extraction technique.

Crambe seed oil: Extraction and reaction with dimethyl carbonate under pressurized conditions

In this study, the efficiency of dimethyl carbonate as a solvent in the pressurized liquid extraction (PLE) of crambe seed oil and also as the acyl acceptor in the transesterification reaction using the mixture obtained, simulating a sequential process, was investigated. In the PLE process, the effect of temperature (140–180 °C) on the yield and quality of the oil was evaluated, and the results were compared to data obtained applying Soxhlet extraction. The reaction of the PLE mixture was conducted from 250 to 350 °C. The results showed greater oil removal from the seeds under pressurized conditions, reaching a yield of ∼45%, which was higher than the yield obtained with Soxhlet extraction. The fatty acids and acylglycerols composition of the extracts obtained with the two methods were similar. However, the phytosterols and tocopherols contents of the oil obtained by PLE were around ∼62% and ∼574% higher, respectively, compared with the oil from the Soxhlet extraction. The best results in the reaction step for ester yield (66.5%) and triglyceride conversion (98.5%) were obtained at 300 °C.

Pressurized liquid extraction applied for the recovery of phenolic compounds from beetroot waste

Abstract Beetroot (Beta vulgaris L.) residues, leaves and stems, normally disposed as animal feed or compost, were investigated for the recovery of valuable compounds by pressurized liquid extraction (PLE) at temperature of 40 °C and pressures of 7.5, 10 and 12.5 MPa, and flow rate of 3 mL min-1. This abundant residue, combined with the lack of related studies of beetroot waste by applying the PLE methods to obtain bioactive extracts is the main novelty of this work. Then, the objective was to explore the PLE process to enhance the value of the residues, evaluating process yield, total phenolic content (TPC) and antioxidant activity (DPPH, ABTS and FRAP methods) of the recovered extracts. Chemical composition was analyzed using LC-ESI-MS/MS and GC-MS analysis. Antioxidant potential results suggest the recovered extracts are comparable with synthetic antioxidant (BHT). Ferulic acid, vitexin and sinapaldehyde, were the most abundant phenolic compounds obtained from the extracts. These results indicate that PLE technique can be a good alternative for extracting phenolic compounds of beetroot resides with high biological potential that could be used in formulations for nutraceuticals, functional food or pharmaceutical industry.

Pressurized liquid extraction with ethanol as a green and efficient technology to lipid extraction of Isochrysis biomass

This work was the first time to establish a green pressurized liquid extraction (PLE) process to extract microalgal lipids from Isochrysis biomass. PLE with ethanol exhibited superior lipid extraction performance in comparison to Soxhlet and Folch methods and PLE with n-hexane. To reduce the cost in ethanol utilization, ethanol concentration was optimized and found that PLE with 90% ethanol concentration obtained the highest lipid extraction efficiency (41.5 wt%) and total fatty acids (TFAs) recovery value (92.17 wt%) using Isochrysis sp. biomass. Results about lipid class detected by TLC-FID technique showed that ethanol concentration distinctly affected the content of lipidic class during lipid extraction by PLE. Similarly, the process with 90% ethanol concentration achieved over 90 wt% of TFAs recovery values with three different Isochrysis species. Overall, PLE process mediated with ethanol was a promising approach to extract Isochrysis-derived lipids from sustainable microalgal biomass for food application.

Antioxidant Activity and Phenolic Content of Campomanesia Phaea Extracts Obtained by Pressurized Liquid Extraction

Objective:This research used the Pressurized Liquid Extraction process (PLE) to obtain cambuci extracts rich in phenolic compounds and, consequently, with high antioxidant activity.Methods:We determined the centesimal composition and the mean particle size of the dried and crushed sample for characterization of the fixed bed extractor. Extractions with pressurized ethanol were performed following a Central Composite Design (CCD) with temperature (60 °C at the center point with ± 10 °C amplitude) and the contact time between the solvent and the matrix (6 min at the center point with ± 2 min amplitude) as independent variables in the process. The Total Phenolic Content (TPC) of compounds and antioxidant activity were determined.Results:The mean particle size of the cambuci in the PLE was 263.4 μm with apparent and real densities of 32.42 g/cm3and 1.62 g/cm3, respectively, resulting in a fixed bed porosity of 0.43. The centesimal composition of the comminuted and dried sample was 12.5 ± 0.1% moisture, 3.2 ± 0.2% ash, 3.35 ± 0.07% crude protein, 10.32 ± 0.08% crude fiber and 0.35 ± 0.04% ethereal extract. The highest extraction yield (41.7%) was obtained by using the binomial 70 ºC with 8 min of solvent contact in three batches. Extracts with the highest TPC (6501.10 mg AGE/100 g sample) were obtained by the binomial 74 °C with 6 min of contact; the binomial 50 °C with 4 min of contact gave rise to the extract with the highest antioxidant activity. The CCD showed high yield extracts with high antioxidant activity and a high total phenolic compound content.Conclusion:With the use of the proposed experimental design, it was possible to optimize the extraction of total phenolic compounds from the sample.

Pressurized liquid extraction of bioactive compounds from grape marc

Extracts rich in monomeric anthocyanins (MAC) and total phenolic compounds (TPC) were obtained from grape marc by Pressurized Liquid Extraction (PLE). PLE was performed using ethanol and water mixtures (acidified or not) (50% w/w), pure ethanol and acidified water at temperatures from 40 to 100 °C. The best PLE conditions for MAC extraction (ethanol-water pH 2.0 [50% w/w]) resulted in 10.21 mg of malvidin-3-O-glucoside/g of dried grape marc (dr). Fifteen anthocyanins were identified and quantified in PLE extracts by UHPLC-UV-Vis. PLE with ethanol-water (50% w/w) as solvent at 100 °C achieved the highest TPC content (65.68 mg GAE/g dr) and antioxidant capacity by ORAC (772.11 μmol TE/g dr) and FRAP (1452 mg TE/g dr) among the evaluated conditions. Based on the results for extraction of monomeric anthocyanins and phenolics compounds, a sequential PLE process was performed and proved to be viable for the recovery of two different extract fractions.

Determination of cinnamaldehyde, carvacrol and thymol in feedstuff additives by pressurized liquid extraction followed by gas chromatography–mass spectrometry

Specific blends of essential oils (BEOs) are promising substitutes for antibiotics to promote livestock performance and to reduce the incidence of intestinal disorders. Microencapsulation of BEOs has shown to improve their stability, bioavailability and to control their release rate once they are added to the feedstuff. The development and validation of a method for determining essential oil components such as carvacrol, thymol and cinnamaldehyde in a microencapsulated material used as feed additive is presented. Analytes were extracted from feed additives and feedstuff by pressurized liquid extraction (PLE) with methanol at 50°C for 5min. Methanol provided good recovery values and cleaner extracts than other polar organic solvents tested. However, for certain kind of composite additives ethyl acetate showed to be a better option because trans-cinnamaldehyde undergoes chemical reaction in methanol. Then PLE extracts were analysed by gas chromatography coupled to ion trap mass spectrometry in selected ion storage (SIS) mode. The analyte stability and the absence of analyte losses during the PLE process was checked by a recovery study. Also, the matrix effect was studied to assess accuracy. Recovery values were between 85 and 115% in most cases. Intra- and inter-day relative standard deviation values were less than 4 and 14%, respectively. Finally, the developed method was applied to the analysis of a microencapsulated feed additive, several composite feed additive samples containing microencapsulated BEOs and a spiked feedstuff, for quality control and in stability studies.

Supercritical fluid and pressurized liquid extractions of phytonutrients from passion fruit by-products: Economic evaluation of sequential multi-stage and single-stage processes

This work presents the economic evaluation of two processes to obtain: i) four extract fractions from passion fruit bagasse by sequential multi-stage process comprising three steps of supercritical fluid extraction (SFE) and one step of pressurized liquid extraction (PLE); ii) one extract from passion fruit rinds by single-stage PLE process. The economic simulation and sensitivity study were performed for plants containing two extraction vessels of 1, 5, 50 and 500L. The scale-up led to a decrease in the cost of manufacturing (COM). COMs of extracts from sequential multi-stage and single-stage processes decreased from US$ 220.51/kg to US$ 26.33/kg and US$ 71.03/kg to US$ 11.96/kg, respectively, when the system capacity increased from 2×1L to 2×500L. Itemized costs related to materials, facilities, labor and utilities are also presented. Both processes are economically promising, especially when the extracts are produced in large scale and sold by the current market price.

Transformations of Tetrahydrocannabinol, tetrahydrocannabinolic acid and cannabinol during their extraction from Cannabis sativa L.

The presented study discusses the difference in the results of estimation of Δ9-tetrahydrocannabinol (THC), tetrahydrocannabinolic acid (THCA) and cannabinol (CBN) amount in Cannabis sativa L., using long-lasting liquid extraction in the Soxhlet apparatus and pressurized liquid extraction (PLE) as sample preparation methods in the analytical procedure. THC amounts extracted in the PLE process using nhexane or methanol are very similar. THCA amounts extracted in the PLE process using n-hexane are generally greater than those extracted in the Soxhlet apparatus but smaller when methanol is applied in the PLE process. The obtained results evidently show that the mutual transformations of THCA, THC and CBN occur not only during Soxhlet extraction but also during short-lasting PLE. In the last case, however, they are small. The intensity of the transformation depends on the applied extractant type.

The Influence of Purge Times on the Yields of Essential Oil Components Extracted from Plants by Pressurized Liquid Extraction

The influence of different purge times on the yield of the main essential oil constituents of rosemary (Rosmarinus officinalis L.), thyme (Thymus vulgaris L.), and chamomile (Chamomilla recutita L.) was investigated. The pressurized liquid extraction process was performed by applying different extraction temperatures and solvents. The results presented in the paper show that the estimated yield of essential oil components extracted from the plants in the pressurized liquid extraction process is purge time-dependent. The differences in the estimated yields are mainly connected with the evaporation of individual essential oil components and the applied solvent during the purge; the more volatile an essential oil constituent is, the greater is its loss during purge time, and the faster the evaporation of the solvent during the purge process is, the higher the concentration of less volatile essential oil components in the pressurized liquid extraction receptacle. The effect of purge time on the estimated yield of individual essential oil constituents is additionally differentiated by the extraction temperature and the extraction ability of the applied solvent.