Microwave assisted hydro-distillation of essential oils from fresh ginger root (Zingiber officinale Roscoe)

A solvent free in situ microwave hydro-distillation method for extraction of essential oil from fresh ginger root it presented. Extraction was conducted in a TE10n single-mode microwave cavity and variable power 2 kW generator operating at 2.45GHz. The main extracted components identified by gas chromatography (GC) were Zingiberene, α-Curcumene, β-Sesquiphellandrene and α-Selinene. At energy inputs of 0.40 kWh/kg higher powers and shorter exposure times, crucially did not degrade the highly volatile components (α-Pinene and Camphene) despite providing the highest essential oil yields. Optimum processing conditions were found to be 1000W (0.40kWh/kg) for 5 min, for whole ginger root, where 0.35g oil/100g plant was obtained. This was compared to a yield of 0.2g/100g plant in 150 min in using conventional hydro-distillation and 0.3g/100g plant in 90 min using a multi-mode microwave cavity-based hydro-distillation

The Efficient Extraction of β-Carotene from Sea Buckthorn Berries Using a Novel Solvent, Fatty Acid Ethyl Esters, and a Combination of Ultrasound and Microwave

The move towards environmentally friendly processing has been a driving force for research into green methods for the extraction of bioactive compounds from plant materials. In this study, a green and efficient process for the extraction of β-carotene from sea buckthorn berries through the simultaneous use of ultrasound and microwave, using a novel green solvent, fatty acid ethyl esters (FAEE), is described. For the same extraction time (45 min), the β-carotene content in the extract was significantly increased (according to ANOVA analysis—p < 0.05) by the simultaneous use of ultrasound and microwave, compared with the separate use of these technologies—an increase of 15 and 89% compared with ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE), respectively. The resulting extract can be used directly, without further purification, as a food supplement because the solvent itself is safe for consumption. Furthermore, FAEE contains omega-3 and omega-6 fatty acids which add to the health benefits of the extract. When β-carotene is extracted from the plant matrix, it is subjected to degradation due to oxidation, but the addition of the antioxidant vitamin E (13 mg/mL of extract) to the extract extends its stability to more than 90 days at room temperature even when exposed to light. The addition of vitamin E also enhances the health benefits of the extract

Optimization of microwave assisted delignification of wood residues by surface response methodology

[EN] Efficient processing of vegetal biomass is a great challenge to current research studies. This work is focused on improving the yield of enzymatic hydrolysis of wood residues by removal of lignin using a alkaline wash assisted by microwave heating. The treatments were carried out for one hour in a pressurized microwave reactor (Synthwave-Milestone). The performance of the treatments was assessed by monitoring the concentration of lignin (determined by UV absorbance at 320 nm against a calibration curve). Each experiment was carried out in duplicate. The treatment conditions were established according to an experimental matrix constructed (in Design Expert 11) after the careful selection of the most important factors that affect the lignin removal from wood residue: concentration of NaOH solution, liquid to solid ratio and temperature. A central composite design was constructed with the independent factors mentioned above. ANOVA indicated adequate fitting of the model (correlation coefficient R2=0.95). The exploration of the experimental space (figure 1) with the fitted model indicates the dominant effect of temperature as independent factor. Optimization of experimental conditions within the experimental space was carried according to the following criteria: minimization of temperature, liquid to solid ratio and NaOH concentration and maximization of the response variable, the lignin concentration. The optimal solution (141 mg lignin / g dry wood residue) proposed by the model for these optimization criteria indicates a point in the region determined by the following coordinates: 0.4M NaOH, 1070C and a ratio of liquid to solid equal to 50.The authors acknowledge the financial support received from the Competitiveness Operational Programme 2014 - 2020, Action 1.1.4: Attracting high-level personnel from abroad in order to enhance the RD capacity, ID project: P_37_471, MY SMIS 105145, Ultrasonic/Microwave nonconventional techniques as new tools for nonchemical and chemical processes, financed by contract: 47/05.09.2016.Trifan, A.; Calinescu, I.; Vinatoru, M.; Gavrila, A. (2019). Optimization of microwave assisted delignification of wood residues by surface response methodology. En AMPERE 2019. 17th International Conference on Microwave and High Frequency Heating. Editorial Universitat Politècnica de València. 217-224. https://doi.org/10.4995/AMPERE2019.2019.9861OCS21722

Growth of nannochloris algae in the presence of microwaves (continuous reactor)

[EN] Algae are very effective in capturing the sun's energy, carbon dioxide from the atmosphere, and nutrients to turn them into useful substances (carbohydrates, oils, proteins, etc.). Besides the main metabolites, there are also secondary metabolites, such as carotenoids (astaxanthin, β-carotene, lutein, lycopene, and canthaxanthin [1]). Both major and compounds existing in small amounts in algae are useful. Oils and carbohydrates could provide biofuels, proteins can get products with nutritional value and from carotenoids can be prepared food supplements. Obtaining biofuel from algae has not yet proved to be economically viable [2, 3]. A much higher interest might be getting food supplements from algae. To increase their value as ingredients for food supplements, algal oils should have a higher degree of unsaturation (rich in omega 3) and an increased carotenoid content to be an important additional benefit in over all processing of algae. There are studies that refer to the influence of environmental factors on algae composition [2], but the microwave influence on algae growth, especially algal metabolites composition change is very poor studied. In this paper, besides the experiments for the activation of algal growth in discontinuous reactors [4] additional work was conducted in a continuous photobioreactor. The goal was checking not only the growth of microalgae but also their content in polyunsaturated oil and in carotenoids. By microwave-controlled irradiation of the nutrient and algae flux, which is recirculated through the photobioreactor and through a glass reactor located in a TE-type monomod cavity, the lipid content of the algae increased, but only, the modification of the lipid fraction content was significantly increased in the concentration of polyunsaturated acids with 16 and 18 carbon atoms. As far as carotenoids are concerned, the algae nannochloris has a higher carotenoid content over many known vegetables holding carotene or lycopene (carrots or tomatoes). Besides oil increasing microwave treatment produced a significant increase in carotenoid content of algae. They can be extracted together with omega-3-rich algal oil and are the basis of very valuable dietary supplements.The authors acknowledge the financial support received from the Competitiveness Operational Programme 2014-2020, Action 1.1.4: Attracting high-level personnel from abroad in order to enhance the RD capacity, project: P_37_471, „Ultrasonic/Microwave Nonconventional Techniques as new tools for nonchemical and chemical processes”, financed by contract: 47/05.09.2016Calinescu, I.; Vintila, A.; Diacon, A.; Vinatoru, M.; Chipurici, P.; Galan, AM.; Velea, S. (2019). Growth of nannochloris algae in the presence of microwaves (continuous reactor). En AMPERE 2019. 17th International Conference on Microwave and High Frequency Heating. Editorial Universitat Politècnica de València. 203-209. https://doi.org/10.4995/AMPERE2019.2019.9820OCS20320

New insights into the role of selective and volumetric heating during microwave extraction: investigation of the extraction of polyphenolic compounds from sea buckthorn leaves using microwave-assisted extraction and conventional solvent extraction

We report a direct comparison of microwave heating and conventional heating in solvent extraction by using exactly the same reaction conditions (including heating rate) in the extraction of polyphenols from dried sea buckthorn leaves. We have for the first time decoupled the effects of bulk heating rate and mixing regime from the fundamental microwave heating mechanism. We show that although microwave selective heating can increase the yield and quality of the polyphenols extracted, if the same bulk heating rate is applied there is no difference in treatment time and therefore theoretical energy requirements of the process. The first implication of these results for process intensification is that if microwave selective heating can be enhanced in scaled up processes through electromagnetic design, the extract yield and quality may be increased further. The second implication is that conventional extraction processes could be designed to provide the same heating rate and hence treatment time as microwave extraction, but any potential energy and space savings would have to be balanced against the increase in capital cost and complexity of the equipment. That said, the very small penetration depth of microwaves into ethanol/water solvent also poses design challenges in the scale up of microwave equipment

Utilization of dielectric properties assessment to evaluate the catalytic activity and rate of deactivation of heterogeneous catalysts

The use of dielectric property assessment to gauge the catalytic activity and rate of deactivation of heterogeneous catalysts is reported. Four supported catalysts containing a combination of Fe and Ni active sites and γ-Al₂O₃, ZSM-5, MCM-41, and SBA-15 supports were synthesized, characterized, and utilized to catalyze a Fischer–Tropsch process over a temperature range of 250–400 °C that was specifically directed toward the production of lower olefins. While the highest conversion was obtained from ZSM-5 and MCM-41 supports containing Fe and Ni as active sites at 350 °C, all these catalysts were observed to be deactivated by the formation of carbon on their surface. The dielectric properties of the fresh, used catalysts and supports were evaluated and correlated with their catalytic activity and structural/textural properties. It was clearly shown that the dielectric property measurement could demonstrate both the presence and magnitude of carbon deposits on the catalyst via the differences in the values of fresh and used catalysts. Furthermore, the ability to differentiate between the levels of the carbon deposition observed was shown to be independent of the morphology exhibited by the carbon deposit demonstrating that this is a method that can be generally applied

Methods of Obtaining Extracts from <i>Hedera helix</i> L. Leaves and Evaluation of the Total Saponins Content

Hedera helix L. is known for its therapeutic properties, such as analgesic, anti-inflammatory, expectorant activity. It is currently known that the characteristic therapeutic effects of ivy extracts are induced by phytocompunds, such as: saponins (hederagenin, α and β-hederin, hederacoside B and C), phytosterols (sitosterol, stigmasterol, campesterol), flavonoids, falcarinol, falcarinone, scopoline, chlorogenic acid, caffeic acid, phytoestrogens [1]. The purpose of our study was to evaluate the total saponin content of Hedera helix L. leaves extracts obtained by both conventional, and unconventional methods. The commercial fresh leaves of Hedera helix L. were purchased from Hofigal SA, Romania. The following reagents used for testing were α-hederin, hederagenin, and hederacoside C at purity ≥98% (HPLC), DMSO were purchased from Sigma Aldrich. The chemical composition of the obtained extracts was analyzed by HPLC-MS/MS, and the total saponin content was evaluated [2,3]. Our study indicated an optimal method for obtaining Hedera helix L. leaves extract with an enriched saponin content