Architectured cellular and bulk ceramic materials based on SiC and graphene/SiC with enhanced transport properties

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Inorgánica. Fecha de lectura: 11-12-2015Esta tesis doctoral ha sido financiada por el proyecto MAT 2009- 09600, y la beca FPI nº BES-2010-041382, del Gobierno de España

El doctor Centeno

Estudio preliminar, edición y notas de Isabel Román Román sobre la novela de Benito Pérez Galdós: El doctor Centeno.Preliminary study, edition and notes of Isabel Román Román on the novel by Benito Pérez Galdós: El doctor Centeno

Microencapsulation of supercritical CO2 extracted rice bran oil in pea proteins

Póster presentado en: 1er Encuentro Ibérico de Fluidos Supercríticos/1º Encontro Ibérico de Fluidos Supercríticos. 2020, 18-19 de febrero, Santiago de CompostelaRice bran oil is a source of bioactive molecules such as sterols, tocols, -oryzanols and unsaturated fatty acids [1,2]. In this work, the encapsulation of rice bran oil extracted using supercritical CO2 under the conditions optimized by Benito-Román et al. [3] has been studied. Microencapsulation processes are sequential and involve the emulsion formation and then, the emulsion drying. In a first stage, the emulsification process by high pressure homogenization was studied and optimized. High pressure homogenization, also known as microfluidization, is a high energy emulsification method affected by several parameters: pressure and number of homogenization cycles (together determine the energy input), the carrier material, the carrier to core ratio, and the solids content in the emulsion. Microfluization also exhibits an important advantage: the industrial application due to flexibility to control the emulsion droplet size (EDS) and the ability to produce emulsions from a variety of materials [4]. Among the different encapsulation materials, vegetable proteins are trendy, due to their properties and the possibility to be used in pharma, cosmetics and food industries [5]. More specifically, pea proteins present the most interesting properties such as emulsifying easiness, high nutritional value and non-allergenic characteristics [6]. For these reasons, and the wall forming properties pea proteins have, key in microencapsulation processes, they were used in this work. The effect of working pressure (60-150 MPa), composition of the carrier (mixtures of pea protein isolate (PPI) and maltodextrin (MD), (from 50 to 90% of PPI) and carrier to oil ratio (COR) (from 2 to 4) on the emulsion droplet size (EDS) was studied, using the response surface methodology. The number of passes through the homogenization chamber was previously determined and set in 7. The experimental work, revealed that in order to minimize the EDS, moderate pressures (114 MPa), a carrier composed mainly by PPI (64%) and carrier to oil ratios around 3.2 are required. Important interactions between the experimental factors were also observed. In the second stage, the emulsion obtained in the optimal conditions (EDS=189±3nm) was dried using different technologies: spray-drying (Buchi B-290 mini Spray-dryer, inlet temperature 155 ºC, outlet temperature 92-96 ºC and emulsion flow rate of 3 g/min); PGSS-drying (apparatus extensively described by Melgosa et al. [7], being the main working conditionsgas to product ratio (GPR) equal to 30 g/g temperature and pressure in the static mixer of 105 ºC and 10 MPa, respectively) and freeze drying (Labconco Freeze Dry System, 0.15 mbar for, at least, 48 h). All of them were suitable to get dry powders, spray drying provided high encapsulation efficiencies (around 73%) and monomodal powders (around 18 μm), whereas PGSS drying provided lower encapsulation efficiencies (around 52%) but perfect spheres with lower particle size (around 11 μm). Freeze drying yielded powders with almost complete encapsulation efficiencies, and higher stability when stored at 4 ºC, since spray-dried and PGSS-dried powders increased the amount of free oil after two weeks of storage.JCyL and ERDF for financial support of project BU301P18. CampofríoFood Group -SIGMA through project ref. 10/16/BU/0017, funded by ERDF of the EU and JCyL, through IC

Subcritical water extraction of quercetin and derivatives from onion skin wastes (Allium cepa cv. Horcal): effect of temperature and solvent properties

Trabajo presentado en: EIFS2022, the 2nd Iberian Meeting on Supercritical Fluids (2º Encontro Ibérico de Fluidos Supercríticos / 2º Encuentro Ibérico de Fluidos Supercríticos), to be held on 28.February - 2.March 2022 in Coimbra, Portugal.Nowadays, the society is immersed in the transition from a linear to a circular economy, in which the value of products, materials and resources is maintained in the economy for as long as possible and the generation of waste is minimized. This means that the byproduct of a process becomes the input of a new one where it acquires new value. Among other agricultural by-products, onion (Allium cepa L.) skin wastes offer great potential for valorization. Onion is the second most important horticultural crop worldwide. More specifically, Spain, in the year 2018 produced 1.27 Mt [1]. The onion industry generates every year more than 0.5 Mt of Onion Skin Wastes (OSW) worldwide [2], including skins (the outermost layers), roots and bulbs unfit for consumption. The non-edible brown skin and external layers of onions are rich in phenolic compounds, mainly flavonoids such as quercetin (QC) [3] and its derivatives: quercetin 4’-O-β- glycoside (QC4’), quercetin 3,4’-O-β-diglycoside (QC3,4’) and quercetin 3-O-β- glycoside (QC3). All of them are high-added value natural antioxidants [2]. The main drawback of quercetin and quercetin derivatives is the limited solubility in water, which limits their oral bioavailability [4] and extractability, and forces the use of an organic solvent to successfully extract them. Alternatively, Subcritical Water (SubW) can be used to extract flavonoids from onion skins. SubW refers to water at temperatures ranging from 100 °C (boiling point) to 374 °C (critical point) which remains in a liquid state due to the application of pressure. Changes in the working conditions change the properties of the SubW (among them, viscosity, surface tension and dielectric constant, which can be similar to those of some organic solvents), enhancing mass transfer and the extractability of barely water-soluble bioactive compounds, as summarized by Benito-Roman et al. [5], as SubW favors the hydrolysis of the bonds between phenolic compounds and the vegetable matrix. In this work the extraction, identification and quantification of phenolic compounds from OSW has been studied using SubW in a semicontinuous extractor (flow rate constant and equal to 2.5 mL/min; temperatures up to 180 °C with working pressure of 5 MPa, to keep water in liquid state). The extraction of flavonoids resulted to be fast (<30 min) and temperature sensitive (maximum at 145 °C; total flavonoids, 27.4±0.9 mg/g OSW). Further increases of temperature decreased the number of flavonoids recovered. The experimental results were fitted to the Weibull model. The influence of the solvent properties on the flavonoids quantification was found to be critical. A precipitate was formed once the extracts cooled down. If removed, a significant fraction of the high temperature extracted flavonoids (as much as 71%, at 180 °C) was lost. This fact affected especially to those compounds that show extremely low solubility in water at room temperature, whereas quercetin glycosylated derivatives were less affected by the polarity change of the medium induced by the temperature change. It has been demonstrated that it is necessary to re-dissolve the subcritical water extracts by the addition of ethanol, which led to a medium with a polarity equivalent to that obtained with water at high temperature. At 145 °C, quercetin (15.4±0.4 mg/g OSW) and quercetin-4’-glucoside (8.4±0.1 mg/g OSW) accounted for the 90% of the total flavonoids identified by HPLC, according to the method described by Benito-Román et al. [6]. All in all, the obtained extracts resulted to be rich in flavonoids, which makes them suitable to be used as food additives in order to replace other synthetic antioxidant compounds.This work was supported by AEI [PID2019-104950RB-I00 and PID2020-116716RJ-I00] and JCyL and ERDF [BU050P20] [BU301P18

Carga parasitaria de la cabra montés Capra pyrenaica victoriae

Parasitic infections in the Iberian ibex are common, serious and well documented. Most studies, however, focus on the subspecies Capra pyrenaica hispanica, found in the south and east of the Iberian peninsula, and few studies have investigated the subspecies Capra pyrenaica victoriae in the centre of the peninsula. Here we add to the information about C. p. victoriae, analyzing samples of this subspecies in the National Park of Sierra de Guadarrama. We found parasites in 97% of samples and identified a total of 11 helminth taxa. The most abundant genus in the analysis was Muellerius. Despite the frequency of parasites, the general health of the population seemed good.Las infecciones parasitarias en las cabras montesas ibéricas son frecuentes, graves y están bien documentadas. Sin embargo, la mayoría de trabajos se centran en la subespecie Capra pyrenaica hispanica, distribuida por el sur y el este de la península ibérica, mientras que hay pocos estudios dedicados a la subespecie presente en el centro de la península, Capra pyrenaica victoriae. Aquí aportamos información sobre C. p. victoriae, analizando muestras coprológicas de esta subespecie en el Parque Nacional de la Sierra de Guadarrama. Hemos encontrado parásitos en el 97% de las muestras e identificado un total de 11 taxones de helmintos. El género más abundante en los análisis ha sido Muellerius. En cualquier caso, la salud de la población parece, en general, buena de tal forma que las cargas parasitarias detectadas no influyen aparentemente de manera determinante en el estado de salud de la población.Depto. de Biodiversidad, Ecología y EvoluciónFac. de Ciencias BiológicasTRUEpu

Valorization of rice bran: modified supercritical CO2 extraction of bioactive compounds

In this work, as a first step in a comprehensive strategy for the valorization of rice bran, the extraction of oil using supercritical CO2 and ethanol as cosolvent has been studied. The effect of extraction temperature (40 and 60 °C), pressure (30 and 40 MPa) and amount of ethanol used (0, 5 and 10%) has been considered. The quality extracted oil has been evaluated in terms of antioxidant activity, fatty acid profile and bioactive compounds such as phenolics, flavonoids, γ-oryzanols, and tocopherols content. Results revealed that, using neat CO2, the best oil in terms of antioxidant activity was obtained at 40 °C and 30 MPa. However, the addition of ethanol as modifier significantly increased the amount of bioactive molecules extracted and hence the overall antioxidant activity of the oil, which was maximum at 40 MPa and 10% ethanol, regardless the temperature. The use of ethanol also affected the amount of fatty acids and γ-oryzanols extracted.Junta de Castilla y León and the European Regional Development Fund (ERDF) for the financial support of project BU301P1

Demographic trends of a reintroduced Iberian ibex Capra pyrenaica victoriae population in Central Spain

One reintroduced population of Iberian ibex was monitored between 2000 and 2007 in the Sierra de Guadarrama National Park (Central Spain) using the distance sampling method. The densities obtained from three samplings show a significant increase between 2000 (6.57 ind./km2 ) and 2007 (33.16 ind./km2 ) despite a range extension. After an initial period of balance, the sex ratio became unbalanced over time in favor of females. The age pyramid also changed after a dramatic population increase. The birth rate oscillated at relatively high values for the species (0.69–0.99 kids/female). The group size reduced significantly over time. Females with kids dispersed from the release area significantly less than males and mixed groups

Pectin methylesterase inactivation by High Pressure Carbon Dioxide (HPCD)

In the present work the effect of High Pressure Carbon Dioxide (HPCD) on the activity and structure of a commercial pectin methylesterase (PME) was studied and the results were compared to the conventional thermal inactivation technology. The use of supercritical CO2 (pressure 6–18 MPa, temperature 40–55 °C and time up to 75 min) increased dramatically the PME inactivation rate. The experimental data fitted the first order model and the inactivation kinetic study of PME was completed with the calculations of the activation energy and volume of activation. HPCD treatment induced important changes in the tertiary structure of the enzyme, as revealed the intrinsic fluorescence, KI quenching and ANS binding analyses. They showed that HPCD treatment rearranged the structure of the enzyme. These changes induced by HPCD were significantly different from those induced by mild thermal treatment. Finally, the structural changes detected correlated with the enzyme activity losses observed.Spanish Ministry of Economy and Competitiveness for financial support of project CTQ2015-64396-R and A.E. Illera’s contract. To Junta de Castilla y León and ERDF for financial support of project BU055U16 and O. Benito-Román’s Post-doctoral contract. To Spanish M

Development of a highly efficient production process for recombinant protein expression in Escherichia coli NEB10β

Altres ajuts: COST Action CM 1303 - Systems BiocatalysisRecombinant protein expression in E. coli is well described, with multiple strains and process strategies available. However, strains used for cloning and molecular biology purposes are not generally considered for protein expression. Using these strains could result in a simplification of the production pathway of a newly cloned protein of interest. In this work, the E. coli strain NEB10β has been characterized for the expression of the complex fusion protein phosphite dehydrogenase-cyclohexanone monooxygenase (PTDH-CHMO), and a production process has been developed based on the PBAD expression system. A fed-batch approach using a defined medium supplemented with amino acids, with glycerol as a carbon source, allows for an efficient recombinant protein expression process, incrementing 9.2-fold the production obtained in a complex medium batch and reaching around 2 g/L of product after 6 h of induction. The process was successfully reproduced in a NEB10β strain for the production of the alcohol dehydrogenase (ADH) enzyme

Integral valorization of agro-food biomass through pressurized fluids. Case study: Brewery Spent Grain (BSG)

Póster presentado en: 1er Encuentro Ibérico de Fluidos Supercríticos/1º Encontro Ibérico de Fluidos Supercríticos. 2020, 18-19 de febrero, Santiago de CompostelaThe biorefinery concept involves the valorization and conversion of biomass into different bioproducts, including energy, materials and chemicals that can replace products derived from fossil carbon sources. The integral valorization of biomass requires the extraction and fractionation of the different constituents thereof, extractables, lipids, proteins and structural components such as cellulose, hemicellulose and lignin. In this work, the use of emerging and clean technologies for the integral valorization of different types of biomass is proposed. First, the use supercritical CO2 (SCCO2) extraction is proposed for recovering the lipid fraction and ultrasonic assisted extraction to recover the hydrophilic fraction, to subsequently perform a fractionation and hydrolysis of the residual biomass using pressurized liquid water. Several types of biomass are being studied, both second and third generation. Among second generation biomass, the brewery spent grain (BSG), which accounts for 85% of the by-products generated in beer processing [1], has been selected as case study of this communication. The extraction of the lipid fraction with SCCO2 has been carried out in a 26.5 mL capacity extractor at different pressures (20-40 MPa) and temperatures (40-80 °C). The lipid fraction obtained has been characterized by determining its lipid profile and antioxidant capacity. The experiments of fractionation and hydrolysis in subcritical water (scW) have been carried out in a semi-continuous reactor, varying the extraction temperature. The different fractions obtained have been characterized by HPLC with two series detectors, UVD and RID, to determine the content in monomeric sugars and oligomers. Protein, free amino acids, total polyphenols and total organic carbon have been also determined. The composition of the BSG according to the biomass characterization protocols of NREL [2] was 21.1 % arabinoxylans, 25.6 % glucanes, 5.1 % soluble lignin, 10.5 % insoluble lignin, 1.2 % ashes, 16.7 % proteins, 5.6 % lipids and 14.4 % extractables. Worth noting the presence of insoluble lignin as well as the high content of arabinoxylans and glucanes, 10% of which were residual starch. The extraction curves obtained when studying the extraction of the lipid fraction of BSG with SCCO2, showed that the extraction rate and the extraction yield increased with increasing temperature and pressure, with the major fatty acid being linoleic acid. Regarding fractionation of the carbohydrate fraction, we have observed that, as temperature increases, hydrolysis increases. Figure 1a shows the sugars yield, including monomeric sugars and oligomers. Degradation of sugars due to the high residence times produces acids (Fig. 1b), hydroxymethylfurfural (HMF) and furfural (Fig. 1c). The treatment of biomass by scW, allows also recovering the entire protein fraction by increasing the temperature up to around 185ºC. In addition, partial hydrolysis of the protein fraction occurs, obtaining as major free aminoacids valine, aspartic acid, alanine and glycine. We can conclude that the fractionation of BSG through emerging and clean technologies allows an integral recovery of BSG, obtaining extracts with high antioxidant capacity. Pressurized water hydrolysis allows the recovery and fractionation of the carbohydrate and protein fraction.JCyL and ERDF for financial support of project BU301P18. To Hiperbaric, S.A. for financial support of Project BIOLIGNO