Microwave-assisted methanolysis of green coffee oil

AbstractOptimisation of a microwave-assisted methanolysis was performed to obtain cafestol and kahweol directly from green coffee oil (Coffea arabica). A two-factor (the methanolysis period and temperature), three-level, factorial experimental design (32) was adopted. The methanolysis procedure was performed under microwave irradiation, using closed vessel and accurate fast responding internal fibre-optic temperature probe. The effects on the responses were measured by HPLC. After 3min of microwave irradiation (hold time) at 100°C, with 500mg of green coffee oil, a yield higher than 99% was obtained. The yield of this reaction is 26% after 2h when working under conventional heating. The methods described in the literature lead to long reaction times, poor yields and formation of side products. The microwave-assisted technique proved to be faster, avoided undesired side products and gave better conversion, when compared to conventional heating process

ULTRASOUND-ASSISTED EXTRACTION OF OIL FROM KIWIFRUIT (Actinidia Deliciosa) SEEDS

This study reports experimental kinetic data and modeling for the extraction of oil from kiwifruit seeds by ultrasound-assisted extraction (UAE) with ethanol. The fatty acid profile, tocopherol and total lipids content in the oil obtained were determined. The variables temperature and ultrasonic power were investigated based on the oil extraction yields using a central composite experimental design. The overall yields obtained were compared to conventional Soxhlet extraction with n-hexane and with ethanol. The extractions presented high extraction rates with overall yield ranged between 19 and 33%, and the extraction yields increased with the temperature. The fatty acid profile showed a high content of omega-3 fatty acids (63.20%) and the Vitamin E content was 14.97 ± 0.38 mg/100 g oil, with ɤ-tocopherol constituting 49% of the total tocopherol. A second-order kinetic model was applied to describe the ultrasound extraction process under different conditions. The numerical results were compared with the experimental extraction yields and presented a good correlation. The extraction technique investigated was found to be suitable for extraction of oil from kiwifruit seeds, in which the great potential of kiwifruit oil obtained from UAE was demonstrate

Materials selection for optimum energy production by double layer expansion methods

NOTICE: this is the author’s version of a work that was accepted for publication in Journal of Power Sources. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Power Sources (2014) DOI:http://dx.doi.org/10.1016/j.jpowsour.2013.12.125The capacitive mixing procedure for energy extraction based on Double Layer Expansion (CDLE) belongs to the group of so-called CAPMIX techniques, which aim at obtaining energy from the salinity difference between fresh and sea waters. Specifically, the CDLE technique takes advantage of the voltage rise that occurs when sea water is exchanged for river water in a pair of porous electrodes which jointly behave as an electrical double layer supercapacitor. In this article, we deal with some experimental aspects that are key for optimizing the extracted energy, and have not been analyzed yet with sufficient detail. This investigation will help in evaluating those parameters which we need to be fixed in a future CDLE device. These include the charging potential, the durations of the different cycle steps, the load resistance used, and the porosity and hydrophilicity of the carbon.Departamento de Física Aplicada, Universidad de GranadaThe research leading to these results received funding from the European Union 7th Framework Programme (FP7/2007-2013) under agreement No. 256868. Further financial support from Junta de Andalucía (Spain), project PE-2008-FQM3993 is also gratefully acknowledged

Labdane dimers from Xylopia aromatica

From the stem bark of Xylopia aromatica (Annonaceae), have been isolated two new labdane dimers as their methyl esters, together with the known compounds ent-labda-8(17),13(16),14-trien-18-oic acid, sitosterol and stigmasterol. The structures of the dimers were elucidated on the basis of detailed spectroscopic analyses. (C) 1999 Elsevier B.V. Ltd. All rights reserved

Iridoid glucosides from Randia spinosa (Rubiaceae)

An iridoid glucoside: randinoside, along with five known iridoids: galioside, deacetylasperulosidic acid methyl ester, scandoside methyl ester, gemposide and gardenoside, were isolated from the stems of Randia spinosa. The structures were determined by spectroscopic analysis, including 2D NMR techniques. (C) 2003 Elsevier Science Ltd. All rights reserved.63439740

Phenylpropanoid glucosides from leaves of Coussarea hydrangeifolia (Rubiaceae)

Phenylpropanoid glycosides, 1 '-O-benzyl-alpha-(L)-rhamnopyranosyl-(1 ''-> 6 ')-beta-(D)-glucopyranoside (1) and alpha-(L)-Xylopyranosyl(4 '', 2 ')-(3-O-beta-(D)-glucopyranosyl)-1 '-O-E-caffeoyl-beta-(D)-glucopyranoside (2), together with the known derivatives, 1,6-di-O-caffeoyl- beta-(D)-glucopyrano side (3), 1-O-(E)-caffeoyl-beta-(D)-glucopyranoside (4) and 1-O-(E)-feruloyl-beta-(D)-glucopyranoside (5), were isolated from leaves of Coussarea hydrangeifolia. Their structures were determined by IR, HRESIMS, and I D and 2D NMR experiments, and their antioxidant activities, evaluated by assaying the free radical scavenging capacity using the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical as substrate. The antioxidant activities of 3 and 4 (IC50 values of 15.0 and 19.2 mu M, respectively) were comparable to that of the standard positive control caffeic acid, whilst 2 and 5 were only weakly active and 1 was inactive. (c) 2005 Elsevier Ltd. All rights reserved