Conventional Soxhlet Extraction Research Articles

Improved extraction of bioactive compounds from Monteverdia aquifolia leaves by pressurized-liquid and ultrasound-assisted extraction: Yield and chemical composition

Monteverdia aquifolia leaves extracts was obtained using pressurized-liquid extraction (PLE) and ultrasound-assisted extraction (UAE), evaluating, when pertinent, temperature, solvent, solvent/biomass ratio, and sonication amplitude (%), comparing to the conventional Soxhlet extraction (SOX) concerning yield (wt%), total phenolic content (TPC), antioxidant activity (AA), and chemical composition. The highest yield was 8.3% obtained in SOX with ethanol (360 min and ± 78 °C). With the same solvent, UAE reached 6.6% (30 min, 50 °C, amplitude 80%, and solvent/biomass ratio 20 mL g−1), and the PLE reached 5.3% (25 min and 60 °C), corresponding to 79.2% and 63.7% of the SOX yield, respectively. However, UAE and PLE consumed a smaller volume of solvent, operated for a shorter time, and provided improved extracts, with higher TPC and AA, compared to conventional extraction. The extracts proved to be a good source of bioactive compounds, such as Vitamin E, Friedelin, Friedelanol, and Squalene.

A biorefinery approach towards valorization of spent coffee ground: Extraction of the oil by supercritical carbon dioxide and utilizing the defatted spent in formulating functional cookies

The present work was aimed at the valorization of roasted spent coffee grounds (SCG), a major valuable and functional by-product of the coffee processing industry by supercritical fluid extraction (SCFE) of the oil therefrom using carbon dioxide, and utilizing the spent residue for the development of functional cookies. The process parameters of SCFE were optimized and compared with conventional Soxhlet extraction using n-hexane, following which the effect of different entrainers was evaluated under optimized conditions of SCFE (300 bar/50 °C/90 min) to obtain the maximum yield of spent coffee oil. SCFE with methanol and ethanol as entrainers at 30% (v/w) of SCG showed marginally better yields of 17.65% w/w and 16.02% w/w than 15.89% w/w obtained by hexane extraction for 16 h. The residue obtained after extraction (SCGR) was analyzed for total polyphenol content (TPC) and antioxidant activities. The SCGR was used for the preparation of cookies and compared with SCG for their textural, bioactivity, prebiotic activity, and sensory analysis. SCGR at 7% (w/w) showed the highest overall acceptability (7.3) in terms of texture and taste. Thus, the biorefinery approach presented in this work would enable the use of coffee oil as well as the defatted SCGR as a novel ingredient enriched with prebiotic activity in future food formulations.

Utilization of supercritical carbon dioxide (SC-CO2) in lipids extraction from sewage sludge cake: A preliminary study

Sewage sludge containing a large number of lipids that can be recovered and utilised as a promising raw material in the production of biodiesel. Studies have been conducted to extract lipids from sludge using conventional solvent methods. However, all these conventional methods have some limitations such as extensive product separation and long extraction time (between 4 to 8 hours), which lead to high energy consumption. Supercritical carbon dioxide extraction (SFE) which utilises carbon dioxide (CO2) gas at its critical condition as solvent has been studied extensively in various fields for oil extraction especially for plant and vegetative. This is due to the shorter extraction time and the lipids can be easily separated from the extraction system. The present research has undertaken a comparison study of supercritical carbon dioxide (SC-CO2) utilisation in the extraction of lipids from sewage sludge against conventional soxhlet extraction of methanol and ethanol as solvent. The extraction of lipids from sewage sludge utilising SC-CO2 extraction was successfully being conducted with lipids yield of 0.69 % within 0.5 hours at the operating temperature of 50 °C and pressure of 20 MPa. The lipids were easily separated subsequently from the SFE system when CO2 is being released in gas form through the outlet valve during lipids collection. Whilst soxhlet extraction using methanol and ethanol as solvent (sludge: solvent ratio of 1:10) managed to extract 1.95 % and 2.81 % within 4 hours of extraction time at 60 °C, with the additional time needed to separate the lipids from solvent by evaporation.

A simple, selective and eco-friendly method for quantification of polychlorinated biphenyls in sediment samples at ultra-trace levels by headspace solid-phase microextraction-gas chromatography-ion trap tandem mass spectrometry

ABSTRACT An analytical method based on headspace solid-phase microextraction gas chromatography- ion trap tandem mass spectrometry (HS-SPME-GC-ITMS/MS) was optimised and developed for estimating 20 predominant polychlorinated biphenyl (PCB) concentrations in sediment samples. The effect of experimental parameters involving fibre materials, amount of water added, temperature effect, sorption time, stirring effect, and the addition of solvents were examined with gas chromatography-electron capture detector (GC-ECD). The analytical performance of association of HS-SPME-GC-ITMS/MS proposed methodology was examined by spiked sediment with the selected PCB congeners. The repeatability and reproducibility of measurements (n = 6), expressed with relative standard deviation (RSD), was below 13% and 16%, respectively. Good linearity was observed within the concentration range studied and the LODs were between 0.02 and 0.82 ng g−1. Accuracy was assessed by analysing a reference sediment sample with certified concentrations of several PCBs. Standard addition calibrations were done and concentrations of PCBs with the proposed method were in good agreement with the certified PCB concentrations. The method was also efficiently applied to real sample sediment from Bizerte Harbour, revealing the existence of several congeners at level less than 1.1 ng g−1. These obtained results were also on concordance with analysis of this real sample using a conventional soxhlet extraction method. The developed procedure is highly effective and selective, free of organic solvents, relatively simple and fast, and become a suitable alternative for routine monitoring of residues of PCB from sediments at ultra-trace levels.

Effects of different pre-treatments on the properties of polyhydroxyalkanoates extracted from sidestreams of a municipal wastewater treatment plant

The paper deals with effects of two different widespread extraction methods (conventional extraction and Soxhlet extraction) and four different pre-treatments (homogenization with pressure and with blades, sonication, and impact with glass spheres) on the extraction yields and properties of polyhydroxyalkanoate (PHA) extracted from biomass coming from an innovative process (short-cut enhanced phosphorus and PHA recovery) applied in a real wastewater treatment plant. The results show that the two different extraction processes affected the crystallization degree and the chemical composition of the polymer. On the other hand, the extractive yield was highly influenced by pre-treatments: homogenization provided a 15% more extractive yield than the others. Homogenization, especially at high pressure, proved to be the best pre-treatment also in terms of the purity, visual appearance (transparency and clearness), thermal stability, and mechanical performances of the obtained PHA films. All the PHA films begin to melt long before their degradation temperature (Td > 200 °C): this allows their use in the fields of extrusion or compression moulding. SynopsisOptimizing the extraction of PHAs from municipal wastewater gives a double beneficial environmental impact: wastewater treatment and circular bio-based carbon upgrade to biopolymers for the production of bioplastics and other intersectoral applications.

Integrated ultrasound-mechanical stirrer technique for extraction of total alkaloid content from Annona muricata

Ultrasound-mechanical stirrer assisted extraction (UMSAE) of extraction yield, total alkaloid content (TAC) and antioxidant (DPPH) activity from Annona muricata leaves were optimized using response surface methodology. Five factors were screened using Plackett-Burman Design to investigate the variables that significantly influence the extraction yield, TAC and DPPH activity, namely solvent concentration, extraction time, ultrasound power, plant material to solvent ratio, and extraction temperature. According to statistical significance analysis, solvent concentration, ultrasound power, plant material to solvent ratio, and extraction temperature were selected for further optimization of the UMSAE extraction process using a Central Composite Design. ANOVA results exhibited that the obtained models were significant at 95 % confidence level. Satisfactory extraction yields (26.38 %) and TAC (39.73 mg AE/g) were obtained with relatively short extraction time under the optimum conditions compared with conventional Soxhlet extraction. The extract prepared under UMSAE displayed excellent DPPH activity (93.15 %). The optimized UMSAE promoted considerable yield increases 1.59-fold the yield extract, 2.32-fold TAC, and 1.19-fold antioxidant activity if compared to the Soxhlet extraction. This study provides the ideal integrated UMSAE settings for the maximum recovery of total alkaloid content with high antioxidant activity from A. muricata for possible utilization of their leaves in food applications.

Passion fruit seed extract enriched in piceatannol obtained by microwave-assisted extraction

Apart from being food, passion fruit (Passiflora edulis Sims) offers seeds to be used as an oil source, and the residual seed cake from oil extraction contains piceatannol, a molecule that can prevent skin damages. In this work, microwave-assisted extraction (MAE) was evaluated as a technique for the preparation of piceatannol-rich seed cake extracts, and its performance was compared to the conventional Soxhlet extraction. MAE and Soxhlet exhibited different selectivities for the seed cake compounds. A sequential MAE at 87 °C, with 70% EtOH, for 30 min each cycle, provided a fine brown powder with 27.17 ± 0.9 μg of piceatannol per mg of the extract, while Soxhlet extraction for 120 min resulted in a dark lumpy extract containing 13.03 ± 0.4 μg mg−1. Thus, MAE was shown to be a promising alternative to produce a passion fruit seed extract for cosmetic purposes, adding value to a residue from the passion fruit chain by providing a faster extraction and a more color friendly and easier-to-handle product with higher levels of piceatannol in comparison to the conventional method.

Source and Distribution of Polycyclic Aromatic Hydrocarbons (PAHs) in Surface Sediment from Chalong Bay, Phuket, Thailand

This study aimed to investigate the spatial distribution and apportionment of potential sources of the 16 US-EPA priority PAHs in surface sediments of Chalong Bay, Phuket, Thailand. A total 28 of sediment samples were collected from areas with high maritime activity in Chalong Bay, subjected to conventional high recovery Soxhlet extraction, purified with SiO2 column chromatography, and quantified by Gas Chromatography-Mass Spectrometry (GC/MS). Total concentration of PAHs (Σ16PAHs) ranged from 31.15 to 1696 ng g−1 dry weight, with an average of 198.2 ± 318.5 ng g−1 dry weight. Binary diagnostic ratios plots were used to distinguish between petrogenic and pyrogenic sources. Most of the PAHs in sediments originated from pyrolytic sources. PCA analysis explained 82.3 % of the variance by only 4 predominant components. The first principal component (PC1) (26.7 %) was mainly contributed to urban street runoff and municipal wastewater discharge. PC2 (25.8 %) represented vehicular combustion sources, PC3 (19.1 %) was attributed to petrogenic sources, and PC4 (10.7 %) was only associated with Naphthalene. The sources of PAHs distributed around Chalong Bay included oil spills, combustion of fossil fuels by shipping, urban street runoff, and municipal wastewater discharge. Each type of sources affected different locations along shores of Chalong Bay.

Recovery of chlorogenic acid from haskap leaves (Lonicera caerulea) using aqueous two-phase extraction

The concept of a biorefinery can be applied to the haskap plant (Lonicera caerulea), where the berries are harvested but the leaves are an under-utilized resource. In this study, aqueous two-phase extraction (ATPE) was used to extract chlorogenic acid (CGA) from haskap leaves. The consumption of CGA is associated with health benefits and it is sold as a natural health supplement. Two different aqueous two-phase systems (ATPSs), consisting of ethanol/sodium dihydrogen phosphate (NaH2PO4) and ethanol/potassium phosphate dibasic (K2HPO4), were compared. The factors investigated were salt/ethanol composition and extraction time. The ethanol/NaH2PO4 system had higher yield of 85.03 mg CGA/g leaves, partition coefficient of 40.41, and 92.97% extraction efficiency. The yield from conventional Soxhlet extraction was 109.74 mg CGA/g leaves; however, this required a much longer extraction time of 24 h. LC-HRMS also showed the presence of CGA, and possibly lonicerin, rutin, and diosmin isomers in the leaf extracts.

Ionic liquid-based microwave-assisted extraction of lipid and eicosapentaenoic acid from Nannochloropsis oceanica biomass: experimental optimization approach

Lipids and eicosapentaenoic acid (EPA) compounds from Nannochloropsis oceanica biomass were extracted using a combination of ionic liquids (ILs) and microwave-assisted extraction (MAE). When compared to conventional Soxhlet extraction, the proposed novel approach in this paper successfully improved both the yield of total extracted lipids and the EPA content. The effect of selected extraction parameters including the weight of applied IL (tetramethyl ammonium chloride: [TMAm][Cl]) (0.5–2.5 g), reaction temperature (60–100 °C), and process time (5–30 min) on final products was evaluated using response surface methodology (RSM). The optimal values of parameters were determined and three-dimensional response surfaces were plotted from the mathematical models and discussed. The yield of total extracted lipids and the content of EPA were found 19.58 wt% (g g−1 of total biomass) and 37.919 mg g−1 of total FAME respectively, when the extraction process was accomplished in 24.69 min at 88.18 °C and with 1.65 g of ILs. Analysis of variance (ANOVA) was applied in the analysis of experimental data and the R2 of 0.9506 and 0.9517 for total lipid and EPA models, respectively, show that the experimental findings were well aligned with the predicted values. Furthermore, at similar condition, the extraction process was replicated using two other types of ILs namely [EMIM][Cl] and [EMPyrro][Br] to extract the total lipid and EPA. The results showed that [TMAm][Cl] performed better in extracting compounds from microalgae. Based on the findings, this study shows that the combination of ILs mediated in water-based MAE is an environmentally friendly, reliable, and efficacious approach to enhance the extraction of lipids and EPA from N. oceanica with considerable potential to be up-scaled for commercial applications.

Microwave-Assisted Extraction of Curcuma longa L. Oil: Optimization, Chemical Structure and Composition, Antioxidant Activity and Comparison with Conventional Soxhlet Extraction

Curcuma root (Curcuma longa L.) is a very important plant in gastronomy and medicine for its unique antiseptic, anti-inflammatory, antimicrobial and antioxidant properties. Conventional methods for the extraction of curcuma oil require long extraction times and high temperatures that can degrade the active substances. Therefore, the objectives of the present study were: (i) first, to optimize the extraction yield of curcuma oil by applying a Box-Behnken experimental design using surface response methodology to the microwave-assisted extraction (MAE) technique (the independent variables studied were reaction time (10–30 min), microwave power (150–200 W) and curcuma powder/ethanol ratio (1:5–1:20; w/v); and, (ii) second, to assess the total phenolic content (TPC) and their antioxidant activity of the oil (at the optimum conditions point) and compare with the conventional Soxhlet technique. The optimum conditions for the MAE were found to be 29.99 min, 160 W and 1:20 w/v to obtain an optimum yield of 10.32%. Interestingly, the oil extracted by microwave-assisted extraction showed higher TPC and better antioxidant properties than the oil extracted with conventional Soxhlet technique. Thus, it was demonstrated that the method applied for extraction influences the final properties of the extracted Curcuma longa L. oil.

Antimicrobial, Antioxidant and Cytotoxic Activities of Cosmos Caudatus extracts

This study aims to investigate the in-vitro antimicrobial potential of Cosmos caudatus against pathogenic bacteria, its antioxidant activity and cytotoxic effect on cancer cell lines. In vitro antimicrobial activities of ethanol and water extracts of Cosmos caudatus herb against pathogenic bacteria, Staphylococcus aureus, Salmonella sp., Pseudomonas aeruginosa and Escherichia coli were tested by agar well diffusion. Antioxidant properties of the extracts was evaluated by 2,2-diphenyl-1-picryl-hydrazyl radical scavenging activity method. Additionally, cytotoxic activity of the extracts on HCT 116 colorectal carcinoma cell line was determined by (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Vero cells were used as a control. The quantification of these extracts showed that this plant is rich in secondary metabolites. Moreover, the conventional soxhlet extraction technique was more effective than maceration and ultrasonic assisted extraction technique. In antioxidants assay, both the ethanolic and water extracts through ultrasonic extraction method exhibited the highest DPPH free radical scavenging capacity compared to maceration and sohxlet extraction method. In antimicrobial assay, both the water and ethanol extracts showed no inhibitory action against the tested pathogenic bacteria. For anticancer activity, the F2, F7 and F8 fractions showed potent dose dependent cytotoxicity on Human Colorectal Carcinoma Cells with IC50 value of 15.53 ± 0.4, 32.72 ± 0.3 and 34.16 ± 1.4 μg/mL, respectively.

Optimization of ultrasound-assisted oil extraction from Canarium odontophyllum kernel as a novel biodiesel feedstock

In this novel study, oil was extracted from the kernel of an exotic indigenous species known as Canarium odontophyllum via an ultrasound-assisted process. The extraction process was optimized using response surface methodology (RSM) based on the Box-Behnken experimental design (BBD). The optimal conditions for the investigated parameters were determined as ultrasound amplitude level: 38.30%, ratio of n-hexane to kernel powder: 50:1 in mL/g, extraction time: 45.79 min, resulting in an oil extraction yield of 63.48%. For verification purposes, experiments were conducted using the same optimized values of the investigated parameters which resulted in the average oil yield of 63.27% and this prove the reliability of the regression model. The extracted oil’s fatty acid composition was obtained using a gas chromatograph (GC) equipped with flame-ionization detection (FID). The low acid value of the extracted oil is another interesting finding. This is important because it circumvents pretreatment processes such as degumming and esterification prior to the transesterification process. Biodiesel was produced from the oil via ultrasound-assisted transesterification, with a yield of 95.2%. Physiochemical properties of the C. odontophyllum biodiesel were determined, and it was found that all the tested properties comply with fuel specifications based on ASTM D6751 and EN 14214 standards. Significant savings of 52.3% and 80.9% in energy consumption and extraction time, respectively were achieved via ultrasound-assisted extraction compared with the conventional Soxhlet extraction. This study establishes the foundation and the need to further explore the usage of C. odontophyllum as a potential feedstock for biodiesel production.

Evaluation of deep eutectic solvents in the extraction of β-caryophyllene from New Zealand Manuka leaves (Leptospermum scoparium)

Leptospermum scoparium (Manuka) is a small indigenous shrub belonging to the family of Myrtaceae, which is equivalent to a tea tree (Melaleuca alternifolia) in Australia. Manuka leaves are rich in bioactive terpenes such as β-caryophyllene, which are scientifically proven to have potential activities in different areas including antimicrobial, anti-inflammatory, antitumour, antioxidant, and anaesthetic. This research considers for the first time the application of deep eutectic solvents (DESs) as green and sustainable solvents for the extraction of β-caryophyllene (β-CAR) from New Zealand Manuka leaves. The extraction was carried out using twenty-six types of hydrophilic and hydrophobic DESs. Menthol: Lactic acid DES was found to have higher extractability of β-caryophyllene than n-hexane, methanol, and ethanol as reference solvents. Moreover, Menthol: Lactic acid DES at 1:2 molar ratio was more efficient than conventional steam distillation and Soxhlet extraction. Furthermore, β-caryophyllene showed a good stability in menthol: lactic acid DES over 9 days of storage. The final β-caryophyllene concentration (β-CAR=8.713605mg/g Manuka leaf) after 4 cycles of extraction suggests a good reusability of the potential DES. The extraction of β-caryophyllene using this DES was further optimised using RSM (response surface methodology) combined with BBD (Box–Behnken design). The optimum experimental conditions were as follows: temperature 25.07°C, stirring time 1.09h, and % w/v biomass of 14.99%, which gave an extraction yield of 10.25mg of β-caryophyllene/g Manuka leaf.

Optimization Study of Marmelosin (Imperatorin) Extraction from Aegle marmelos Using Three Phase Partitioning

Aegle marmelos is a prominent tree in Indian Ayurveda and occupies an important place in Ayurvedic, Unani and Siddha system of Indian medicine due to its ethnomedicinal values. The current work demonstrates the use of three-phase partitioning (TPP) for the first time to isolate and purify a potent bioactive compound marmelosin from A. marmelos fruit. Marmelosin exhibits antibacterial, anticancer, hepatoprotective and antidiabetic activity. Here, various experimental conditions were optimized for TPP, and comparison was made between conventional techniques like Soxhlet and batch extraction. The impact of various TPP parameters such as ammonium sulphate concentration, solute to solvent ratio, time, slurry to t-butanol, and pH on the yield of marmelosin was studied. TPP shows maximum marmelosin yield of 0.494 mg/g at the optimized condition as solute to solvent ratio 1:50 , time 2.5 h, ammonium sulphate concentration 30 w/v %, slurry to t- butanol ratio 1:1, pH 5. Conventional techniques, i.e., Soxhlet and batch extraction, resulted in yield of 0.250 mg/g in 7 h and 0.150 mg/g respectively in 4 h. Thus, TPP enhances the yield as well as reduces the extraction time that shows it is a simple, effective, promising, and cost-effective technique for the extraction of marmelosin thereby reducing the processing time.

Supercritical Fluid Extraction of Polyphenols from Vietnamese Callisia fragrans Leaves and Antioxidant Activity of the Extract

Vietnamese Callisia fragrans (C. fragrans) has been considered as a valuable traditional plant with various medicinal properties. In this study, polyphenols were extracted from Vietnamese C. fragrans leaves by supercritical carbon dioxide (SC-CO2) extraction method using ethanol as a cosolvent. The investigation of four factors influencing the total polyphenol content (TPC) and antioxidant activity of the extracts obtained from each single-factor experiment was conducted including ethanol concentration, CO2 flow rate, extraction temperature, and pressure. Besides, the extraction efficiency of the SC-CO2 method under the best extraction conditions, namely ethanol concentration of 14%, CO2 flow rate of 20 g/min, extraction temperature of 45°C, and pressure of 200 bar was compared to that of the Soxhlet extraction (SE) method in terms of the TPC and antioxidant activity of the extracts. The results showed that using SC-CO2 method, the TPC and the half-maximal inhibitory concentration value obtained were of 87.42 ± 1.33 mg/g and 243.83 ± 5.30 μM TE/g, respectively, with much less time and solvent amount required while that obtained using SE method were of 85.34 ± 4.27 mg/g and 236.33 ± 7.66 μM TE/g, respectively. This indicated that SC-CO2 would be suitable for the industrial production of polyphenols with high antioxidant activity of the extracts obtained due to the restrictions of using the SE method and advantages of applying SC-CO2 method. Therefore, SC-CO2 method could be regarded as a potentially upcoming extraction technique which might be employed to replace the conventional SE method.

Supercritical CO2 extraction of favela (Cnidoscolus quercifolius) seed oil: Yield, composition, antioxidant activity, and mathematical modeling

Cnidoscolus quercifolius seeds were subjected to oil extraction with supercritical CO2 at 40, 50, and 60 °C and 20, 25, and 30 MPa for 120 min at 5 g min−1. The oils obtained were evaluated from the viewpoint of their yield, composition, and antioxidant activity; they were compared with the oil obtained using the conventional Soxhlet extraction method with n-hexane. Sovovás’ mathematical model was used to adjust the kinetic curves. The highest oil yield (41.0 wt%) was obtained at 60 °C and 30 MPa and corresponded to ∼87% of the Soxhlet yield. In this condition, the highest yields of tocopherols and β-sitosterol were obtained, i.e., 8.87 and 51.6 mg 100 gseed−1, respectively. The oils extracted by both the methods showed a similar fatty acid composition with a predominance of linoleic acid (∼60%). The highest antioxidant activity was equivalent to 6.82 mmol of trolox per kg of oil.

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.

A comparative assessment of biological activities of Gundelia dersim Miller and Gundelia glabra Vitek, Yüce & Ergin extracts and their chemical characterization via HPLC-ESI-TOF-MS

Plants from the Gundelia genus have been well appraised as both food and remedies. The members of the Gundelia genus are widely used as foods in several countries including Turkey. This study presents a comparative assessment of two poorly studied Gundelia species (G. glabra Miller and G. dersim Vitek, Yüce & Ergin). The effect of conventional (infusion, maceration, and Soxhlet extraction) and non-conventional (homogeniser and ultrasound assisted extraction) methods of extraction of bioactive secondary metabolites from the selected Gundelia species was also assessed. A total of 68 different compounds were detected by high-performance liquid chromatography coupled to electrospray ionization and time-of-flight mass spectrometry (HPLC-ESI-TOF-MS) technique. Non-conventional extraction techniques do not guarantee higher antioxidant activity. As such, G. dersim (91.27, 138.87, 182.28, and 125.65 mg TE [Trolox equivalent]/g dried extract, for 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), cupric reducing antioxidant capacity (CUPRAC), and ferric reducing antioxidant power (FRAP) assays, respectively).The highest α-glucosidase inhibition was recorded for the extracts obtained by ultrasonication. In the multivariate analysis, the extracts from Gundelia species were separated based on their biological activities. The presented findings could be one methodological starting point for designing novel products from two Gundelia species.

Resource Recovery from Waste Coffee Grounds Using Ultrasonic-Assisted Technology for Bioenergy Production

Biodiesel is a proven alternative fuel that can serve as a substitute for petroleum diesel due to its renewability, non-toxicity, sulphur-free nature and superior lubricity. Waste-based non-edible oils are studied as potential biodiesel feedstocks owing to the focus on the valorisation of waste products. Instead of being treated as municipal waste, waste coffee grounds (WCG) can be utilised for oil extraction, thereby recovering an energy source in the form of biodiesel. This study evaluates oil extraction from WCG using ultrasonic and Soxhlet techniques, followed by biodiesel conversion using an ultrasonic-assisted transesterification process. It was found that n-hexane was the most effective solvent for the oil extraction process and ultrasonic-assisted technology offers a 13.5% higher yield compared to the conventional Soxhlet extraction process. Solid-to-solvent ratio and extraction time of the oil extraction process from the dried waste coffee grounds (DWCG) after the brewing process was optimised using the response surface methodology (RSM). The results showed that predicted yield of 17.75 wt. % of coffee oil can be obtained using 1:30 w/v of the mass ratio of DWCG-ton-hexane and 34 min of extraction time when 32% amplitude was used. The model was verified by the experiment where 17.23 wt. % yield of coffee oil was achieved when the extraction process was carried out under optimal conditions. The infrared absorption spectrum analysis of WCG oil determined suitable functional groups for biodiesel conversion which was further treated using an ultrasonic-assisted transesterification process to successfully convert to biodiesel.