Microwave-assisted Solvent Extraction Research Articles

Recovery of Valuable Components from Food Wastes by Microwave Assisted Extraction

Today, insufficiency of natural resources, rapidly growing world population, climate change, food losses and food waste cause significant risk for food safety. In food industries, high amounts of solid and liquid wastes are released at various stages of production. The majority of them are organic wastes left from the raw material processed. Food waste, food and nutrition safety and food quality affect the sustainability and economic development of food systems and have negative impacts on natural resources and environmental protection. In addition, these food wastes can be converted into useful products which have market value, such as polyphenols, dietary fiber and photochemistry etc. Therefore, studies on the assessment of these wastes are becoming increasingly important and quick and effective new applications are needed. Traditional extraction methods usually take a long time and require large amounts of solvent. Microwave assisted solvent extraction (MASE) is one of the modern methods which have been used more commonly in recent years, with short extraction time, less solvent usage and lower energy requirements, higher heating rates, higher extraction efficiency, higher selectivity and better quality target products. Microwave assisted solvent extraction is one of the modern methods with its increasing use in recent years. In this study, microwave extraction has been studied in general and the studies on the extraction of valuable components by microwave extraction technique from food wastes were compiled. Keywords: Food waste, Microwave assisted extraction DOI: 10.7176/JSTR/6-09-05

Microwave-assisted solvent extraction and double-shot analytical pyrolysis for the quali-quantitation of plasticizers and microplastics in beach sand samples

Pollution from microplastics (MPs) needs to be evaluated by deploying reliable analytical techniques that provide qualitative and quantitative data on the extent of contamination in the various environmental matrices. Solvent extraction of MPs followed by pyrolysis-gas chromatography-mass spectrometry (Py-GC–MS) provides data that not only regard the soluble plastics, but also the organic additives contained in MPs and the low-molecular weight degradation products of insoluble plastics. In this study, the potential of microwave-assisted solvent extraction and double-shot Py-GC–MS was investigated in order to obtain quali-quantitative information on polystyrene and on phthalate plasticizers in environmental samples. The method was validated and provided recoveries higher than 96 %, and detection limits lower than 1 ng and 1 μg for phthalates and polystyrene, respectively. We used the method to analyze samples of sand collected from a shoreline in Tuscany (central Italy) and thereby determine the content of phthalates and polystyrene at different depths and distances from the coastline. Qualitative data were also obtained regarding the presence of oxidation products derived from polyethylene and polypropylene. The different contents of plasticizers, plastics, and degradation products in the investigated samples are discussed in relation to how environmental agents affect the leaching and degradation processes of the polymers.

Enhanced solubility of microwave-assisted synthesized acyclovir Co-crystals

This study aimed to enhance the kinetic solubility of ACV by using microwave-assisted technique to form ACV co-crystals and overcome its limited aqueous solubility. Co-crystallization is one of the commonly used techniques to improve the dissolution rates of active pharmaceutical ingredients (APIs). Acyclovir (ACV) has a limited efficacy due to its low oral bioavailability resulted from its poor aqueous solubility and permeability. Acyclovir co-crystals were formulated by microwave assisted solvent extraction (MASE) in equimolar ratio of 1:1 with different co-formers. Physical and structural characterization by differential scanning calorimetry (DSC), powder x-ray diffraction (PXRD), and Fourier transform infrared (FTIR) spectroscopy were performed. Further evaluation of the co-crystals solubility, dissolution rate and content were carried out using the ultraviolet (UV) spectrophotometry. Co-crystals of acyclovir and tartaric acid (ACV-TA) in equimolar ratio of 1:1 produced by MASE using the glacial acetic acid as a solvent were more soluble compared to plain drug. The dissolution rate was increased from only 59.0% of pure acyclovir up to 85.0% of ACV co-crystals within 1 hour. DSC and PXRD patterns of co-crystals were distinguished from that of individual components. The UV-spectroscopic analysis represented 62.5% of acyclovir in the co-crystals, which was directly related to the theoretical percentage of the drug and its co-former (ACV: 60.01%, TA: 39.99%). This study revealed that the optimal ratio of the ACV-TA co-crystal is 1:1, which was successfully prepared using MASE technique. This method provides a promising alternative for enhancing the solubility of acyclovir with ultimately less time and solvent consumption.

Simultaneous HPLC-PDA determination of commonly prescribed antidepressants and caffeine in sludge from sewage treatment plants and river sediments in the Itaipu reservoir region, Paraná, Brazil

ABSTRACT Antidepressants are widely used in current times; therefore, they pose a potential risk to ecosystems through the disposal of domestic sewage, even after processing in treatment plants. This study proposes a fast method for the simultaneous determination of commonly used antidepressants (citalopram, venlafaxine, fluoxetine, sertraline, and amitriptyline) and caffeine as an anthropic marker, based on microwave-assisted solvent extraction followed by quantification using HPLC-DAD. The analytical method was validated and considered satisfactory for the simultaneous determination of the analytes in sewage sludge and sediments. No interferences were observed in the retention times of the analytes under study, indicating selectivity. Nevertheless, the study of the matrix effect revealed interference of the sludge and sediment matrices in the sensitivity and accuracy of the analytical method; therefore, calibration by standard addition was employed. The linearity was adequate for the concentration range of 50–800 ng mL−1, with detection and quantification limits of 15–100 ng g−1 and 100–250 ng g−1, respectively. Precision was estimated to be less than 8% in terms of the coefficient of variation. Accuracy was assessed by fortification of sediment and sludge samples at three concentration levels and the recovery range varied from 60 to 99%. The developed and validated method was applied to samples of sewage sludge and sediments obtained from the Itaipu Reservoir region. The results confirm the presence of the analytes in the sewage sludge and indicate that treatment plant residue is a route of insertion of micropollutants into the local environment, because the antidepressants were also found in river sediments.

Energy consumption analysis of lipid extraction from black soldier fly biomass

Black soldier fly larvae containing high lipids had been considered an novel sustainable feedstock for lipid extraction to biofuels. The insect lipid was extracted with microwave assisted solvent extraction method. The energy consumption of this way was analyzed to determine the feasibility of the lipid extraction process. The comparison of the effects of different extraction conditions (dehydration methods, water content, extraction temperature, extraction time, equipment power, and solute-solvent ratio) on the energy consumption of lipid extraction from the energy insect was investigated systematically. The dewatering of the insect biomass was the most energy consuming step via a dry extraction method in this paper, constituting about 40–80% of the total energy consumption demand. Within the ranges of extraction factors values compared in this analysis, the microwave radiation powder and lipid extraction temperature had a pronounced effect on the total energy consumption in the ranges of investigated parameter. At last, the lipid extraction yield-dependent evolution of energy consumption for different extraction conditions was also investigated. Anyway, the economic and environmental aspects of lipid extraction from the energy insect needed to be further improved for its large scale implementation in the future.

Anti-Multiple Myeloma Potential of Secondary Metabolites from Hibiscus sabdariffa

Multiple myeloma (MM) belongs to hematological cancers and its incidence is increasing worldwide. Despite recent advances in its therapy, MM still causes many deaths every year. In fact, current therapies sometimes fail and are associated with severe adverse effects, including neurotoxicity. As a part of our ongoing efforts to discover new potential therapies against MM, we prepared Hibiscus sabdariffa extracts obtained by a microwave-assisted solvent extraction and investigate their activity by in vitro assays on the RPMI-8226 cell line. The bioguided fractionation of the crude ethanolic extract allowed the identification of HsFC as the most effective extract. We assessed cell viability (MTT and Tripan blue test), cell migration (Boyden chamber assay), and neurotoxicity (DRG neurotoxicity assay). The promising results prompted us to further fractionate HsFC and we obtained two molecules effective against RPMI-8226 cells without neurotoxic effects at their active concentrations. Moreover, both compounds are able to significantly reduce cell migration.

Optimization of microwave-assisted solvent extraction of non-edible sandbox (Hura crepitans) seed oil: A potential biodiesel feedstock

In this study, modeling and optimization of the microwave-assisted solvent extraction (MASE) of sandbox seed oil (SSO) were investigated. D-optimal design with two numeric (extraction time (5–15 min), heating power (180–540 W)) and two categoric (solid/solvent ratio (1:10–1:40) and solvent type (ethyl acetate, n-hexane and acetone)) factors was used to model and optimize SSO yield. The model developed had coefficient of determination (R2) of 0.9821, indicating it can be used to adequately describe the MASE process with high accuracy. Optimum SSO yield of 72.20 ± 0.35 wt% could be obtained using extraction time of 5 min, microwave heating power of 180 W, solid/solvent ratio of 1:40 and ethyl acetate as solvent of extraction. Performance evaluation of the solvents in terms of oil yield showed that ethyl acetate was the most efficient (72.20 ± 0.35 wt%) followed by acetone (57.90 ± 1.27 wt%) and n-hexane (56.25 ± 1.77 wt%). Physicochemical properties of the SSO varied depending on the solvent of extraction. Fatty acids profile of the SSO showed that it had more unsaturated (79.7–84.5%) fractions than saturated (15.5–20.2%) fractions. Therefore, SSO could serve as feedstock for biodiesel and other oleochemical production.

Optimization of microwave-assisted extraction of bioactive compounds from pistachio (Pistacia vera L.) hull

ABSTRACTPhenolic compounds were extracted from pistachio hull using microwave-assisted solvent extraction (MASE). The effects of four parameters, microwave power, extraction time, solvent to sample ratio, and ethanol concentration were evaluated. The extraction conditions were optimized by response surface methodology to enhance the total phenolic content (TPC). Optimal conditions were found as 140 W microwave power, 4.5 min extraction time, 19:1 (v/w) solvent to sample ratio, and 56% ethanol concentration to get maximum TPC (62.24 mg GAE/g dry hull). Also, MASE was compared with conventional solvent extraction (CSE) and MASE gave higher TPC, yield, and antioxidant activity.

The use of a microwave-assisted solvent extraction coupled with HPLC-UV/PAD to assess the quality of Marrubium vulgare L. (white horehound) herbal raw material.

Marrubium vulgare is a herbal remedy presents in several European Pharmacopoeias and commonly marketed as white horehound. The chemotaxonomic marker of Marrubium genus is marrubiin and its content may change in response to biotic and abiotic stress. Development of a microwave-assisted solvent extraction (MASE) methodology suitable for exhaustively extracting marrubiin from M. vulgare leaves, easily applicable to large sets of samples. Evaluation of the influence of copper(II) on marrubiin production. M. vulgare leaves were dried, extracted exploiting MASE and analysed via high-performance liquid chromatography ultraviolet photodiode array detection (HPLC-UV/PAD) system. A design of experiments approach was adopted to select the best extraction conditions. Extraction parameters (solvent composition, extraction time and temperature), were studied applying two full factorial experimental designs in a sequential approach. To analyse samples, a rapid HPLC-UV/PAD method was set up. The best results in terms of marrubiin extraction yield were obtained extracting samples at 120°C with 100% ethanol, for 15min (3 × 5 min microwave cycles). The developed methodology was successfully applied to matrices grown in Greenhouse conditions and under stress induced by copper(II), selected as model agent for abiotic stress. Progressively decreasing production of marrubiin was evidenced in connection with treatment with 80, 200 and 300mg/L copper sulphate. An efficient methodology for the extraction and determination of the amount of marrubiin in large sets of samples of M. vulgare plants was developed. Results demonstrated that marrubiin is an easily detectable marker useful for evaluating M. vulgare reaction to stress.

Effect of Solvents and Extraction Methods on Forskolin Content from Coleus forskholii Roots

Coleus forskohlii roots are mainly used for extraction of the bioactive diterpenoid, forskolin, which has enormous biological activities. In this study, impact of the solvent and extraction method on forskolin content from Coleus forskohlii root powder was investigated. Nine solvents from different polarity group were tested for forskolin extraction. It was found that the efficiency of the solvents used to extract forskolin varied considerably (0.18 to 2.91 %). The average values indicated that among all the extractives, forskolin content was significantly higher in methanol (2.91 %), followed by ethanol (2.59 %), and least content was found in water (0.18 %). Low polarity solvents were not found very effective for forskolin extraction. Further three different extraction methods (Soxhlet/refluxing, ultrasound and microwave-assisted solvent extraction) were also compared using safest and most effective solvent for forskolin yield. As ethanol exhibited good extraction efficiency for forskolin and is a safe solvent, it was chosen for further optimization of extraction method. Soxhlet extraction technique gave higher yield of forskolin (0.17 to 2.83 %) compared to microwave-assisted solvent extraction (0.09 to 2.29 %) and ultra sound-assisted extraction (0.08 to 1.47 %). From these results it was evident that the extraction of forskolin depended on extraction process as well as the solvent used.

Chemical investigations of bitumen from Neolithic archaeological excavations in Italy by GC/MS combined with principal component analysis

An analytical protocol involving microwave assisted solvent extraction followed by GC/MS and principal component analysis (PCA) of the chromatographic data was used for the characterization of bituminous residues sampled from Neolithic objects recovered from excavations in Italy.

Microwave-assisted solvent extraction of castor oil from castor seeds

Abstract This study was aimed at evaluating the physicochemical properties and oxidation stability of castor oil using microwave-assisted solvent extraction (MAE). MAE was performed using 5% ethanol in hexane as solvent at different extraction times, power intensities and solvent-to-feed (S/F, ml of solvent to gram of feed) ratios. The process parameters were optimized by statistical approach using historical data design of response surface method (RSM). The oils were characterized for yield, physicochemical properties, dielectric properties and oxidation stability, and comparison was also made with oil extracted using Soxhlet method. Results show that the maximum oil yield of 37% was obtained at 20 min with microwave power intensity of 330 W and S/F ratio of 20. The main fatty acid composition of castor oil is ricinoleic acid. The density, refractive index, dielectric properties and oxidation stability of oils are not affected by the extraction methods and extraction parameters of MAE. However, the MAE-extracted oil is more viscous compared to that by Soxhlet method. With extra caution on oil oxidation, MAE could be a promising solvent extraction method with an 86% less in processing time and a higher yield.

The impact of high-power ultrasound and microwave on the phenolic acid profile and antioxidant activity of the extract from yellow soybean seeds

The aim of the study was to investigate and compare several extraction protocols like 1) high-power ultrasound probe assisted solvent extraction; 2) microwave assisted solvent extraction; 3) direct acid hydrolysis; 4) direct alkali hydrolysis, and 5) two step extraction consisting of ultrasound or microwave assisted solvent extraction followed by alkaline and acid hydrolysis in terms of efficiency of the extraction of phenolic acids from the yellow soybean seed variety Laura. These extracts were screened for their total phenol content (TPC), and for their antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl radical scavenging (DPPH) assay, as well as on content of some individual phenolic acids. It appeared that the acetone containing mixtures gave much higher TPC than methanol containing ones, but the presence of acid in the methanol solvent significantly improved the extraction of phenolic compounds. To further improve the extraction, an ultrasound lab-scale probe at 20 kHz was used, with 15 and 30% of the maximum amplitude, and the extraction time was varied from 2 to 15 min. Microwave assisted extraction was performed varying the temperature from 55 to 85 °C, microwave power from 25 to 100 W and extraction time from 2 to 10 min. Changes in the content of six phenolic acids were examined: gallic, trans-cinnamic, chlorogenic, caffeic, p-coumaric and ferulic acid. The separation and quantification of phenolic acids was accomplished by high-performance liquid chromatography-diode array detection (DAD) procedure. The results suggested that microwaves contributed to more efficient extraction of phenolic acids from the seed of yellow soybean. The amount of phenolic acids varied from 65.52 μg/g of dry matter (d.m.) for caffeic acid, to 581.84 μg/g d.m. for p-coumaric acid. Both, ultrasound and microwaves contributed to more efficient extraction of total phenol compounds and enhanced antioxidant activity of soybean seed extracts. TPC varied from 12.48 to 18.77 mg GAE/g d.m. and antioxidant activity varied from 244.58 to 345.21 μmol TROLOX eq/g d.m.

A new approach for the extraction of tetracyclines from soil matrices: application of the microwave-extraction technique.

The widespread use of tetracyclines (TCs) in animal husbandry is associated with their constant penetration into the environment and the threat they might pose to living organisms. While the literature data on the analysis of these substances in such matrices as food, tissues, or wastewater are quite extensive, there are still only a few methods presented for the determination of these compounds in soil samples. Moreover, among the literature methods for the extraction of TCs from soil samples, microwave-assisted solvent extraction (MAE) was used only once and in combination with liquid chromatography with spectrophotometric detection (LC-UV). However, according to the EU Commission Decision 2002/657/EC, the use of LC-UV for the determination of compounds, including pharmaceuticals, in environmental samples is not sufficient. Therefore, the development and application of a sensitive and selective method using the MAE-SPE-LC-MS/MS(MRM) technique for the isolation and identification of a mixture of oxytetracycline (OTC), tetracycline (TC), and chlortetracycline (CTC) in soils is presented in our study. The credibility of this method has been confirmed with good parameters of validation. The optimal extraction conditions of three TCs using MAE techniques were to conduct double extraction for 10min each, at 60°C, using a mixture of ACN:McIlvaine buffer:0.1M EDTA (2:1:1, v/v/v) and an additional cleaning of the extracts by SPE. The effectiveness of the extraction of these compounds was assessed based on two different ways (absolute recovery from 46 to 65.1% and relative recovery from 101.1 to 109.5%). Finally, the validated MAE-SPE-LC-MS/MS(MRM) method was used for the analysis of six samples from agricultural areas of northern Poland. OTC and TC, at concentrations of 11.7 and 14.5μgkg-1 were determined in two different samples. An assessment of risk quotients was also performed. The presented method was proven to be a useful tool in the analysis of residues of selected TCs in the soil ecosystem. Obtained data on the presence of these drugs in Polish soils is the first report for this country.

Comparative evaluation of rice bran oil obtained with two-step microwave assisted extraction and conventional solvent extraction

In the present study, an innovative approach for microwave assisted solvent extraction of rice bran oil (RBO) in two steps termed two-step microwave assisted extraction (TSMAE) has been adopted. Microwave treatment and solvent washing were done alternately in two steps. The effect of microwave power (200, 320, 450, 560 W), microwave exposure time (30, 60, 90, 120 s) and solvent to bran ratio (1.6, 2.3, 3 mL/g) per step on percentage of oil recovery in TSMAE were evaluated. Bran milled at 3–6% degree of polish was evaluated for oil recovery. Oil recovery of more than 95% was obtained in total extraction time of 8–10 min with only 1.6–2.3 mL/g solvent to bran ratio (per step). The overall oil quality obtained in TSMAE was found to be superior to that of conventional solvent extracted oil especially with respect to phospholipid content (0.64 ± 0.11 vs 1.02 ± 0.15%), α-tocopherol content (7.85 ± 0.19 vs 6.83 ± 0.12 mg/g RBO), antioxidant activity (1.50 ± 0.05 vs 1.27 ± 0.08 trolox equivalent antioxidant activity) and free fatty acid content (4.88 ± 0.26 vs 5.77 ± 0.25%). Microstructure analysis revealed cell rupture due to microwave treatment that suggests the reason for faster oil extraction in TSMAE.

Classical and modern drug extraction techniques: facts and figures

In present era, herbal extract succeeds inimitable place in pharmaceutical science. In view back the earliest extraction techniques are lost in the mists of history. As time went the plants have been processed by grinding, boiling or immersing. The systemic presentation of Ayurvedic extraction system has been first time familiarized by Acharya Charaka as Panchavidha Kashaya Kalpana (five basic primary dosage forms) and based upon these primary dosage forms, secondary dosage forms are developed by using different heating pattern for extraction of pharmacological active ingredients. The administration of these dosage forms is mainly dependent on the Bala (strength) of Vyadhi (disease) and Atura (patient). Due to increased demand of Ayurvedic medicines and industrialization, the transformation of classical dosage forms takes place by implanting a wide range of technologies with different methods of extraction include conventional techniques such as maceration, percolation, infusion, decoction, hot continuous extraction etc. and recently, alternative methods like ultrasound assisted solvent extraction (UASE), microwave assisted solvent extraction (MASE) and supercritical fluid extractions (SFE). The extract obtained by these procedure uses as a large source of therapeutic phyto-chemicals that may lead to the development of novel drugs. Essentially, the purpose behind this changing face in both the extraction systems are different but can say that it is a new insight from ancient essence.

Evaluating Modern Techniques for the Extraction and Characterisation of Sunflower (Hellianthus annus L.) Seeds Phenolics.

Recently there is a great interest in using high energy techniques (HET) which involve microwave or ultrasound-assisted extraction (MAE and UAE) for isolation of natural bioactive compounds from plant foods. Such bioactive compounds are phenolics which were determined from sunflower (Helianthus annuus L.) kernels and hulls (defatted) utilising two different high energy extraction techniques, ultrasound and microwave assisted solvent extraction. All samples were characterised by ultra-high-performance liquid chromatography-electrospray ionization-mass spectrometry (UHPLC-ESI-MS). The effect of parameters such as the nature of the solvent, volume of solvent, temperature and time is discussed. It is proved that the techniques applied had reduced solvent consumption and shorter extraction times, and extraction yields of the analytes were equal to or to some extent higher than those obtained with conventional techniques. Total Phenolic Composition (TPC) of samples examined was studied by the Folin-Ciocalteu method and results were presented in μg gallic acid equivalents (GAE)/g dry extract. Kernels proved to have the higher amount of TPC while the press residues had shown comparable TPC results. The antioxidant activity of samples was spectrophotometrically determined by 2,2-Diphenyl-1-Picrylhydrazyl (DPPH) assay using Butylated hydroxyl toluene (BHT) as reference compound to compare with samples. Sunflower seeds (kernels) showed again the highest antiradical efficiency (AE) compared to hulls and press-residue extract. Afterwards, ferric reducing ability of plasma (FRAP) and trolox equivalent antioxidant capacity (TEAC) assays were used for measuring the antioxidant capacity of samples. Press residue, a by-product of sunflower oil extraction, contained phenolics as shown by UHPLC-ESI-MS analysis. Hence, later on these compounds can be possibly utilised by food or neutraceutical industries. Phenolic substances characterised in hulls, kernels, and press residue were phenolic acids, mainly chlorogenic, caffeic, cinnamic, 4-hydroxybenzoic and p-coumaric.

Simultaneous determination of 106 pesticides in nuts by LC-MS/MS using freeze-out combined with dispersive solid-phase extraction purification.

As a result of the low water content and high fat matrices in nuts, it is very difficult to simultaneously determine multi-pesticides in trace levels. Here, a sample pretreatment method was developed in which, microwave-assisted solvent extraction was firstly used to extract pesticides, and then a two-step cleanup method was conducted combining freeze-out with dispersive solid-phase extraction to remove the lipidic matrix. By this way, 106 pesticides were simultaneously determined in the complicated nut sample by using an ultra-high pressure liquid chromatography coupled with a tandem mass spectrometer. Average recoveries were 75.3-119.3% with relative standard deviations<14% at three concentration levels. The limits of detection and quantification were in the ranges of 0.3-3.0 and 1.0-10.0μg/kg, respectively. Furthermore, the method was successfully applied to the determination of pesticides in 180 commercial nut samples.

Optimisation of Microwave-Assisted Extraction of Pomegranate (Punica granatum L.) Seed Oil and Evaluation of Its Physicochemical and Bioactive Properties.

Pomegranate seed oil was extracted in a closed-vessel high-pressure microwave system. The characteristics of the obtained oil, such as fatty acid composition, free fatty acidity, total phenolic content, antioxidant activity and colour, were compared to those of the oil obtained by cold solvent extraction. Response surface methodology was applied to optimise extraction conditions: power (176-300 W), time (5-20 min), particle size (d=0.125-0.800 mm) and solvent to sample ratio (2:1, 6:1 and 10:1, by mass). The predicted highest extraction yield (35.19%) was obtained using microwave power of 220 W, particle size in the range of d=0.125-0.450 mm and solvent-to-sample ratio of 10:1 (by mass) in 5 min extraction time. Microwave-assisted solvent extraction (MASE) resulted in higher extraction yield than that of Soxhlet (34.70% in 8 h) or cold (17.50% in 8 h) extraction. The dominant fatty acid of pomegranate seed oil was punicic acid (86%) irrespective of the extraction method. Oil obtained by MASE had better physicochemical properties, total phenolic content and antioxidant activity than the oil obtained by cold solvent extraction.

Microwave Assisted Extraction of Olive Oil Pomace by Acidic Hexane

In this study, Microwave-Assisted Solvent Extraction (MASE) was used to recover oil residues from pomace olive using acidic hexane. Results obtained demonstrated that oil extraction yield increased with time, the amount of acetic acid in hexane and power radiation. For both radiation powers used (170 and 510W), the optimal extraction time and most interesting content of acetic acid in hexane are 1.5 minutes and 5.0% respectively. Oil yield obtained at power 510 W was slightly higher than those corresponding to 170 W. Compared to results obtained with pure hexane, the yield increases were 8.4 % at 170 W and 6.0% at 510 W. However, the oil extracted from pomace olive was found to be of poor quality; indeed only phenolic compounds concentration increased significantly with acetic acid content.