ASSESSMENT OF THE INFLUENCE OF PROCESSING CONDITIONS ON THE ANTIOXIDANT POTENTIAL OF EXTRACTS OBTAINED FROM OLIVE OIL INDUSTRY BYPRODUCTS

Tesis por compendio[EN] The main goal of this Thesis was to determine the influence of the main processing stages involved in obtaining natural extracts with high antioxidant potential from byproducts originating in the olive oil industry. Firstly, the effect of freezing and/or the drying methods applied to olive oil byproducts on the polyphenol content and antioxidant capacity of the extracts subsequently obtained was addressed. For this purpose, two byproducts were considered: olive leaves and olive pomace. Secondly, the feasibility of intensifying the extraction of olive leaf polyphenols by means of a new technology, such as power ultrasound, was approached taking both compositional and kinetic issues into account. Thirdly, how the processing conditions (drying and extraction) influence the extract's stability was evaluated. Thus, on the one hand, extracts obtained from olive leaves were subjected to in vitro digestion or dehydrated and stored at different conditions. Finally, the possibility of obtaining a dried vegetable matrix (apple) rich in olive leaf phenolic compounds was explored by addressing the influence of apple pretreatments (blanching and freezing) and drying on the final retention of infused phenolics. The antioxidant potential of extracts and the retention of infused polyphenols in apple were evaluated by means of the total phenolic content and antioxidant capacity analysis, as well as the identification and quantification of the main olive leaf polyphenols by HPLC-DAD/MS-MS. Moreover, in apple samples, the polyphenol oxidase and peroxidase activity and microstructure were also analyzed. The experimental results highlighted that both drying and freezing methods significantly (p<0.05) influenced the concentration of the main polyphenols identified in the olive leaf extracts. Thus, drying at the highest temperature tested was the best processing condition in which to obtain extracts with high antioxidant capacity and phenolic content. Ultrasound application was found to be a relevant, non-thermal way of speeding-up the antioxidant extraction from olive leaves. Thus, by appropriately tuning-up the process variables, the ultrasonic assisted extraction shortened the extraction time from the 24 h needed in conventional extraction to 15 min, without modifying either the extract composition or the antioxidant potential. As far as extract stability is concerned, the processing conditions used for obtaining the olive leaf extracts did not have a meaningful influence on bioaccessibility. Regardless of the method used, stabilizing the extracts by means of dehydration only reduced both the antioxidant capacity and the total phenolic content by around 10 %. Moreover, storage conditions did not show a significant (p<0.05) effect on the antioxidant potential of the extracts for 28 days of storage. A stable dried product (apple), rich in natural phenolic compounds (from olive leaves or tea extracts), was obtained by combining drying-impregnation-drying steps. However, it should be considered that the role of fresh apple drying on the retention of infused olive leaf polyphenols was more important than the further drying of the impregnated apple. In overall terms, olive leaves can be considered a potential source of natural phenolic compounds. Notwithstanding this, the previous drying and freezing steps applied in the raw material processing are decisive factors in the obtaining of natural extracts with high antioxidant potential. Moreover, enhancing the extraction by applying power ultrasound was stated as a non-thermal way of shortening processing times. The stability of olive polyphenols during storage and in vitro digestion was closely related to the individual component considered. Finally, the exploitation of olive leaf extracts as a means of enriching solid foodstuffs requires the use of porous solid matrices free of oxidative enzymes.[ES] El objetivo principal de esta Tesis fue determinar la influencia de las principales etapas de procesado implicadas en la obtención de extractos naturales con alto potencial antioxidante a partir de los subproductos originados en la industria del aceite de oliva. En primer lugar, se evaluó el efecto de los métodos de congelación y/o secado de la materia prima (hojas y orujo), sobre el contenido polifénolico y la capacidad antioxidante de los extractos. En segundo lugar, se abordó la intensificación de la extracción de polifenoles de hoja de olivo con ultrasonidos de potencia, teniendo en cuenta: composición y la cinética del proceso. A continuación, se estudió cómo las condiciones de procesado (secado y extracción) podían influir en la estabilidad de los extractos. Así, extractos de hojas de olivo fueron sometidos a digestión in vitro o deshidratados y almacenados a distintas condiciones. Por último, se exploró la posibilidad de obtener una matriz vegetal deshidratada (manzana) y rica en compuestos fenólicos de hoja de olivo. Para ello, se evaluó la influencia de los pretratamientos de la manzana (escaldado y congelación) y del secado en la retención final de los polifenoles impregnados. El potencial antioxidante se determinó a través del contenido total en compuestos fenólicos y la capacidad antioxidante y la identificación y cuantificación (HPLC-DAD/MS-MS) de los principales polifenoles. Además, en manzana, se midió la actividad enzimática de la polifenol oxidasa y peroxidasa y se analizó la microestructura. Los resultados manifestaron que el método de secado y el de congelación influyeron significativamente (p<0.05) en la concentración de los principales polifenoles en los extractos. Así, el secado a mayor temperatura resultó ser el mejor tratamiento para obtener extractos con alta capacidad antioxidante y alto contenido fenólico. La aplicación de ultrasonidos resultó ser una alternativa no térmica muy interesante para acelerar la extracción de antioxidantes de hojas de olivo. Con la combinación adecuada de las variables del proceso, la aplicación de ultrasonidos redujo el tiempo de extracción de 24 h necesarias en extracción convencional a 15 min, sin modificar la composición de los extractos y su potencial antioxidante. En cuanto a la estabilidad del extracto, las condiciones de procesado no tuvieron una influencia significativa en la bioaccesibilidad de los extractos. Independientemente del método utilizado, la estabilización de extractos por deshidratación sólo redujo la capacidad antioxidante y el contenido total en compuestos fenólicos en torno a un 10 %. Además, las condiciones de almacenamiento no mostraron ningún efecto significativo (p<0.05) sobre el potencial antioxidante durante los 28 días de almacenamiento. Combinando secado-impregnación-secado, fue posible desarrollar un producto deshidratado (manzana), estable y rico en compuestos fenólicos naturales (de hojas de olivo o extractos de té). No obstante, cabe destacar que el secado de la manzana fresca jugó un papel más importante en la retención de los polifenoles de hoja de olivo infundidos que el secado final de la manzana impregnada. En términos generales, las hojas de olivo pueden considerarse como una fuente potencial de compuestos fenólicos naturales. No obstante, el secado y la congelación durante el procesado de la materia prima son factores decisivos para la obtención de extractos naturales con alto potencial antioxidante. Además, la aplicación de ultrasonidos de potencia durante la extracción puede resultar una alternativa no térmica muy interesante de cara a acortar el tiempo de procesado. La estabilidad de los polifenoles de la hoja de olivo, durante el almacenamiento y la digestión in vitro, dependió claramente del compuesto individual considerado. Finalmente, el empleo del extracto de hoja de olivo como medio para enriquecer alimentos sólidos requiere del uso de matrices s[CA] L'objectiu principal d'aquesta tesi va ser determinar la influència de les principals etapes de processament implicades en l'obtenció d'extractes naturals amb alt potencial antioxidant procedents de subproductes de la indústria de l'oli d'oliva. En primer lloc, es va estudiar l'efecte de la congelació i/o els mètodes d'assecatge aplicats a fulles d'olivera i pinyolada sobre el contingut fenòlic i la capacitat antioxidant dels extractes. En segon lloc, es va avaluar, tenint en compte la composició i la cinètica del procés, la intensificació de l'extracció de polifenols de fulla d'olivera amb ultrasons de potència. En tercer lloc, es va avaluar com les condicions de processament (assecatge i extracció) poden influir en l'estabilitat dels extractes. Així, extractes de fulles d'olivera van ser sotmesos a una digestió in vitro o deshidratats i emmagatzemats a distintes condicions. Finalment, es va explorar la obtenció d'una matriu vegetal deshidratada (poma) i rica en compostos fenòlics de fulla d'olivera considerant la influència del pretractament de la poma (escaldament i congelació) i de l'assecatge sobre la retenció final dels fenòlics introduïts en la poma. El potencial antioxidant es va avaluar determinant el contingut fenòlic total i la capacitat antioxidant, així com identificant i quantificant els principals polifenols (HPLC-DAD/MS-MS). A més, en poma l'activitat enzimàtica de la polifenoloxidasa i la peroxidasa i la microestructura. Els resultats experimentals van destacar que el mètode d'assecatge i el de congelació van influir significativament (p<0,05) en la concentració dels principals polifenols identificats en els extractes. L'assecatge a la temperatura més alta que es va provar va resultar la millor condició de processament per a obtenir extractes amb una alta capacitat antioxidant i un alt contingut fenòlic. L'aplicació d'ultrasons va ser una manera rellevant i no tèrmica d'accelerar l'extracció d'antioxidants de les fulles d'olivera. Així, amb la combinació adequada de les variables del procés, l'extracció assistida per ultrasons va escurçar el temps d'extracció, de les 24 h requerides en l'extracció convencional a 15 min, sense modificar la composició de l'extracte ni el potencial antioxidant. Quant a l'estabilitat de l'extracte, les condicions de processament utilitzades per a l'obtenció dels extractes de fulla d'olivera no van tenir una influència significativa en la bioaccessibilitat. Independentment del mètode utilitzat, l'estabilització dels extractes per mitjà de la deshidratació només va reduir la capacitat antioxidant i el contingut fenòlic total al voltant d'un 10 %. A més, les condicions d'emmagatzematge (temperatura i forma de l'extracte: líquid o pols) no van mostrar cap efecte significatiu (p<0,05) en el potencial antioxidant dels extractes durant els 28 dies d'emmagatzematge. Combinant etapes d'assecatge-impregnació-assecatge fou possible obtenir un producte assecat estable (poma) i ric en compostos fenòlics naturals (de fulles d'olivera o te). No obstant això, cal destacar que l'assecatge de la poma fresca va ser més important i determinant en la retenció dels polifenols de fulla d'olivera que no l'assecatge de la poma impregnada. En termes generals, les fulles d'olivera es poden considerar com una font potencial de compostos fenòlics naturals. No obstant això, l'aplicació d'assecatge i congelació durant el processament de la matèria primera són factors decisius per a l'obtenció d'extractes naturals amb un alt potencial antioxidant. A més, l'aplicació d'ultrasons de potència durant l'extracció resultà ser una forma no tèrmica de millorar el procés, tot reduint-ne el temps d'extracció. L'estabilitat dels polifenols d'olivera durant l'emmagatzematge i la digestió in vitro va dependre del compost individual considerat. Finalment, la utilització d'extractes de fulla d'olivera per a desenvolupar aliments sòlids enriquits requAhmad-Qasem Mateo, MH. (2015). ASSESSMENT OF THE INFLUENCE OF PROCESSING CONDITIONS ON THE ANTIOXIDANT POTENTIAL OF EXTRACTS OBTAINED FROM OLIVE OIL INDUSTRY BYPRODUCTS [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/53452Premios Extraordinarios de tesis doctoralesCompendi

Influencia del secado y almacenamiento en el potencial antioxidante de extractos de hoja de olivo (var. serrana)

[ES] Debido a la creciente demanda de extractos antioxidantes naturales, el objetivo del presente trabajo ha sido estudiar la influencia que tiene el secado sobre el potencial bioactivo de extractos obtenidos a partir de hojas de olivo. Además, se ha evaluado el efecto de las condiciones de almacenamiento en la estabilidad de los extractos. En primer lugar, para evaluar la influencia del secado de la materia prima, las hojas fueron deshidratadas por aire caliente a 120 °C y liofilización. Posteriormente, una parte de los extractos fueron deshidratados por aire caliente a: 120 °C y a 55 °C con vacío. Los extractos obtenidos fueron almacenados a 4, 25 y 35 °C en estado líquido ó polvo, determinándose a lo largo del tiempo de almacenamiento (4 semanas) su capacidad antioxidante (CA), contenido total en compuestos fenólicos (CTF) y la concentración de los compuestos fenólicos mayoritarios. Los resultados obtenidos mostraron que tanto el secado del material vegetal como de los extractos influyó en el potencial antioxidante. El secado a 120 °C de las hojas frescas proporcionó los extractos con el contenido fenólico más alto, destacando la concentración de oleuropeína (11,2±0,9 mg/mL). Por su parte, la deshidratación de los extractos redujo, independientemente del método utilizado, la CA y el CTF en torno al 10 %. Por último, no se observó un efecto significativo (p<0,05) de las condiciones de almacenamiento sobre el potencial antioxidante de los extractos.[EN] Due to the increasing demand of natural antioxidant extracts, the aim of this work was to assess the influence of drying on the bioactive potential of extracts obtained from olive leaves. Moreover, the effect of storage conditions on extract stability was evaluated. In order to study the impact of the raw material drying, olive leaves were dried by hot air at 120 °C and freeze drying. After the extraction, a part of the extracts was dehydrated by hot air at 120 °C and hot air at 55 °C by applying vacuum. The obtained extracts (liquids and powders) were stored at 4, 25 and 35 °C for 4 weeks. During this period, the antioxidant capacity (AC), the total phenolic content (TPC) and the concentration of the main phenolic compounds were determined. Results highlighted that drying of both raw material and extracts affected the antioxidant potential. Thus, hot air dried leaves (120 °C) provided the highest phenolic content, especially the oleuropein concentration (11,2±0,9 mg/mL). Regarding the extracts dehydration, independently of the method used, both AC and TPC were reduced around 10 %. Finally, stored conditions did not affect significantly (p<0,05) the extracts antioxidant protential.[CA] A causa de la creixent demanda d'extractes antioxidants naturals, l'objectiu del present treball ha sigut estudiar la influència que té l'assecat sobre el potencial bioactiu d'extractes obtinguts a partir de fulls d'olivera. A més, s'ha avaluat l'efecte de les condicions d'emmagatzemament en l'estabilitat dels extractes. En primer lloc, per a avaluar la influència de l'assecat de matèria primera, els fulls van ser deshidratats per aire calent a 120 °C i liofilització. Posteriorment, una part d’els extractes van ser deshidratats per aire calent a: 120 °C i 55 °C amb buit. Els extractes obtinguts van ser emmagatzemats a 4, 25 i 35 °C en estat líquid o en pols, determinant-se al llarg del temps d'emmagatzemament (4 setmanes) la seua capacitat antioxidant (CA), contingut total en compostos fenòlics (CTF) i la concentració dels compostos fenòlics majoritaris. Els resultats obtinguts van mostrar que tant l'assecat del material vegetal com dels extractes va influir en el potencial antioxidant. L'assecat a 120 °C dels fulls frescos va proporcionar els extractes amb el contingunt fenòlic més alt, destacant la concentració d'oleuropeina (11,2±0,9 mg/mL). Per la seua banda, la deshidratació dels extractes va reduir, independentment del mètode utilitzat, la CA i el CTF prop del 10 %. Finalment, no es va observar un efecte significatiu (p<0,05) de les condicions d'emmagatzemament sobre el potencial antioxidant dels extractes.Ahmad-Qasem Mateo, BH. (2014). Influencia del secado y almacenamiento en el potencial antioxidante de extractos de hoja de olivo (var. serrana). http://hdl.handle.net/10251/56999Archivo delegad

The role of drying methods on enzymatic activity and phenolics content of impregnated dried apple

[EN] Infusion of antioxidants into vegetables is a new food strategy managed by matrix processing. Raw and blanched apple were air- or freeze-dried. In the case of freeze-dried samples, different freezing methods were previously applied: conventional (¿28°C), blast freezing (¿30°C), and liquid N2 (¿196°C). Afterwards, air- and freeze-dried samples at different conditions were impregnated with a concentrated (40°Brix) tea extract and finally, air-dried for their stabilization. Total phenolic content (TPC), antioxidant capacity (AC), enzymatic activity, and microstructure were analyzed. Regardless of pretreatments, the impregnation and the further drying improved the antioxidant potential. Samples with the most porous microstructure free of degradative enzymes provided high AC (78.5¿±¿0.9¿mg Trolox/g dried matter) and TPC (16.7¿±¿0.2¿mg GAE/g dried matter).The authors thank the Ministerio de Educacion, Cultura y Deporte of Spain for its financial support through fellowships from the Programa de Formacion de Profesorado Universitario del Programa Nacional de Formacion de Recursos Humanos de Investigacion and the subprogramas de Formacion y de Movilidad dentro del Programa Estatal de Promocion del Talento y su Empleabilidad, en el marco del Plan Estatal de Investigacion Cientifica y Tecnica y de Innovacion 2013-2016 en I+D+i. This research has also been supported by Unilever Research and Development Vlaardingen and by the Generalitat Valenciana through the project PROMETEOII/2014/005.Ahmad-Qasem Mateo, MH.; Nijsse, J.; García Pérez, JV.; Khalloufi, S. (2017). The role of drying methods on enzymatic activity and phenolics content of impregnated dried apple. Drying Technology. 35(10):1204-1213. https://doi.org/10.1080/07373937.2016.1236344S12041213351

Air- borne ultrasonic application in the drying of grape skin: Kinetic and quality considerations

[EN] The aim of this work was to address the air-borne application of power ultrasound in the convective drying of grape skin, a by-product of winemaking. For that purpose, convective drying experiments were carried out on red grape skin at 40, 50, 60 and 70 C with (21.7 kHz, 45 W) and without power ultrasound application. The kinetic intensification was evaluated by modeling the drying kinetics using empirical and diffusion models. Meanwhile, the quality of the dried product was determined by obtaining ethanolic extracts and assessing the total phenolic content and antioxidant capacity by means of the FRAP method. Moreover, individual polyphenols were identified by HPLC-DAD-ESI-MS/MS and a Partial Component Analysis (PCA) was performed in order to elucidate the relationships between the measured variables that were related to bioactive content. Both temperature and ultrasound application had a significant (p < 0.05) influence on the drying kinetics, which were satisfactorily described by both the Peleg and diffusion models. In addition, both factors significantly (p < 0.05) influenced the total phenolic concentration and antioxidant capacity of the extracts. Ultrasound application reduced the antioxidant potential, probably due to oxidase activation and cell degradation. Bioactive potential, on the other hand, was increased as a consequence of hightemperature drying, leading in particular to a greater release of malvidin 3-O-b-D-galactoside.The authors acknowledge the financial support of the Spanish Ministerio de Economia y Competitividad and ERDF and it is a program of the European Commission ERDF-European Commission (Ref. DPI2012-37466-C03-03); Generalitat Valenciana (PROME-TEOII/2014/005) and the Universitat Politecnica de Valencia (PAID-02-11).Cruz, L.; Clemente Polo, G.; Mulet Pons, A.; Ahmad-Qasem Mateo, MH.; Barrajón-Catalán, E.; García Pérez, JV. (2016). Air- borne ultrasonic application in the drying of grape skin: Kinetic and quality considerations. Journal of Food Engineering. 168:251-258. https://doi.org/10.1016/j.jfoodeng.2015.08.001S25125816

Influence of drying on the retention of olive leaf polyphenols infused into dried apple

[EN] Olive leaf extracts are rich in polyphenolic compounds. Their inclusion by impregnation in food solid matrices could improve the nutritional value and antioxidant capacity of dietary products, such as apple. Drying the food matrix is interesting not only because it speeds up the infusion but also because of its effect on the final stabilization of impregnated food. In this work, the influence of drying method on the retention of infused olive leaf polyphenols in a solid matrix (apple) was addressed. For this purpose, apple cubes (10 mm side) were initially dehydrated by freeze drying or hot air drying at 60 °C and then impregnated with the olive leaf extract. After the polyphenolic infusion, samples were dried for the final stabilization by means of three different methods: freeze drying and hot air drying at 60 °C both with and without ultrasound application. The retention of infused polyphenols in apple samples was evaluated by determining the total phenolic content and antioxidant capacity and quantifying the main olive leaf polyphenols by HPLC-DAD/MS MS. The drying kinetics and the loss of apple solids during impregnation were modeled by using diffusion equations and the Weibull model, respectively. The role of fresh apple drying on the retention of infused olive leaf polyphenols was more significant than the further drying of the impregnated apple. Thus, hot air drying of fresh apple provided the highest antioxidant capacity (47.1±2.6 mg Trolox/g d.m.), and oleuropein contents in the final dried apple of up to 1,928 mg/100 g d.m. were foundThe authors thank the Generalitat Valenciana (PROMETEO/2010/062, PROMETEO/2012/007, and ACOMP/2013/93) for its financial support. M. H. Ahmad Qasem was the recipient of a fellowship from the Ministerio de Educacion, Cultura y Deporte of Spain (Programa de Formacion de Profesorado Universitario del Programa Nacional de Formacion de Recursos Humanos de Investigacion). This research has also been supported by the Ministerio de Ciencia e Innovacion (DPI2012-37466-C03-03, AGL2011-29857-C03-03) and CIBERobn (CB12/03/30038, Fisiopatologia de la Obesidad y la Nutricion, CIBERobn, Instituto de Salud Carlos III.Ahmad-Qasem Mateo, MH.; Santacatalina Bonet, JV.; Barrajón-Catalán, E.; Micol, V.; Cárcel Carrión, JA.; García Pérez, JV. (2015). Influence of drying on the retention of olive leaf polyphenols infused into dried apple. Food and Bioprocess Technology. 8(1):120-133. https://doi.org/10.1007/s11947-014-1387-6S12013381Ahmad-Qasem, M. H., Barrajón-Catalán, E., Micol, V., Mulet, A., & García-Pérez, J. V. (2013a). Influence of freezing and dehydration of olive leaves (var. 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Influence of air temperature on drying kinetics and antioxidant potential of olive pomace

This work aims to evaluate the influence of olive pomace drying (a solid by-product of the olive oil industry) on both antioxidant potential and drying kinetics. The two main fractions of olive pomace (pits, PI and pulps + peels, P + P) were characterized by image analysis and density measurement. The drying process was analyzed in experiments carried out at different temperatures (from 50 to 150 C) and mathematically described from the diffusion and Weibull models. The antioxidant potential of the extracts (ethanol water 80:20 v/v, 22 ± 1 C, 170 rpm for 24 h) obtained from the dry product was analyzed by measuring the total phenolic content and antioxidant capacity and the main polyphenols were quantified by HPLC DAD/MS MS. The drying behavior of olive pomace was well described by considering the diffusion in the PI and P + P fractions separately and the influence of temperature on effective moisture diffusivities was quantified by an Arrhenius type equation. The antioxidant potential was only mildly influenced by the drying temperature. However, long drying times at the highest temperature tested (150 C) significantly (p < 0.05) increased the antioxidant potentialThe authors acknowledge the Generalitat Valenciana (PROMETEO/2010/062 and PROMETEO/2012/007) and Ministerio de Economia y Competitividad (AGL2011-29857-C03-04) for their financial support and the Ministerio de Educacion, Cultura y Deporte of Spain for the financing through the Formacion de Profesorado Universitario del Programa Nacional de Formacion de Recursos Humanos de Investigacion.Ahmad-Qasem Mateo, MH.; Barrajón Catalán, E.; Micol, V.; Cárcel Carrión, JA.; García Pérez, JV. (2013). Influence of air temperature on drying kinetics and antioxidant potential of olive pomace. Journal of Food Engineering. 119(3):516-524. https://doi.org/10.1016/j.jfoodeng.2013.06.027S516524119

Kinetic and Compositional Study of Phenolic Extraction from Olive Leaves (var.Serrana) by Using Power Ultrasound

[EN] Power ultrasound is being used as a novel technique for process intensification. In this study, the feasibility of using power ultrasound to improve the phenolic extraction from olive leaves was approached taking both compositional and kinetic issues into account and also determining the influence of the main process parameters (the electric power supplied, emitter surface and temperature). For this purpose, the extraction kinetics were monitored by measuring the total phenolic content and antioxidant capacity and mathematically described by Naik's model, and HPLC DAD/MS MS was used to identify and quantify the main polyphenols. The electric power supplied and the emitter surface greatly affected the effective ultrasonic power applied to the medium, and hence the extraction rate. However, the influence of temperature on ultrasound assisted extraction was not clear. Compared with conventional extraction, ultrasound assisted extraction reduced the extraction time from 24 h to 15 min and did not modify the extract composition. Industrial relevance: Olive crop produces a significant quantity of byproducts (leaves, branches, solid and liquid wastes), coming from the tree pruning, fruit harvest and oil production, which are rich in phenolic compounds with bioactive properties. The extraction of the bioactive compounds could be an interesting option with which to increase the value of these byproducts, as it requires efficient extraction techniques in order to reduce processing costs and improve productivity. In this sense, ultrasound assisted extraction is considered a novel technique used as ameans of intensifying a slow process, such as the leaching of polyphenols fromvegetablematrices. In order to further address the industrial applications of ultrasound assisted extraction, a kinetic study should be carried out determining both the effective energy introduced into the medium, as well as its influence on the extract quality.The authors thank the Generalitat Valenciana (PROMETEO/2010/062 and PROMETEO/2012/007) for its financial support. M. H. Ahmad Qasem was the recipient of a fellowship from Ministerio de Educacion, Cultura y Deporte of Spain (Programa de Formacion de Profesorado Universitario del Programa Nacional de Formacion de Recursos Humanos de Investigacion).Ahmad-Qasem Mateo, MH.; Canovas, J.; Barrajon-Catalan, E.; Micol, V.; Cárcel Carrión, JA.; García Pérez, JV. (2013). Kinetic and Compositional Study of Phenolic Extraction from Olive Leaves (var.Serrana) by Using Power Ultrasound. Innovative Food Science and Emerging Technologies. (17):120-129. https://doi.org/10.1016/j.ifset.2012.11.008S1201291

Interfacial States and Fano-Feshbach Resonance in Graphene-Silicon Vertical Junction

Interfacial quantum states are drawing tremendous attention recently because of their importance in design of low-dimensional quantum heterostructures with desired charge, spin, or topological properties. Although most studies of the interfacial exchange interactions were mainly performed across the interface vertically, the lateral transport nowadays is still a major experimental method to probe these interactions indirectly. In this Letter, we fabricated a graphene and hydrogen passivated silicon interface to study the interfacial exchange processes. For the first time we found and confirmed a novel interfacial quantum state, which is specific to the 2D–3D interface. The vertically propagating electrons from silicon to graphene result in electron oscillation states at the 2D–3D interface. A harmonic oscillator model is used to explain this interfacial state. In addition, the interaction between this interfacial state (discrete energy spectrum) and the lateral band structure of graphene (continuous energy spectrum) results in Fano–Feshbach resonance. Our results show that the conventional description of the interfacial interaction in low-dimensional systems is valid only in considering the lateral band structure and its density-of-states and is incomplete for the ease of vertical transport. Our experimental observation and theoretical explanation provide more insightful understanding of various interfacial effects in low-dimensional materials, such as proximity effect, quantum tunneling, etc. More important, the Fano–Feshbach resonance may be used to realize all solid-state and scalable quantum interferometers

Validación de métodos de análisis de la composición nutricional de frutos secos y estudio de vida útil del aceite empleado en la fritura de porras

En este trabajo se ha estudiado la influencia de la fritura y el tostado en el contenido en agua, grasa, proteína y fibra total alimentaria de diferentes frutos secos. Además, con el fin de validar los métodos de análisis empleados en la determinación de estos compuestos nutricionales, se ha evaluado su exactitud (por comparación con los resultados proporcionados por un laboratorio certificado) y precisión. Por otro lado, se ha evaluado el efecto que diferentes variables, incluida la adición de antioxidantes (tocoferoles naturales, palmitato de ascorbilo y TBHQ) al medio de fritura, ejercen sobre la vida útil del aceite empleado en la elaboración de porras. Los resultados obtenidos mostraron que no existe un efecto claro de la temperatura de procesado sobre el valor nutricional de los frutos secos analizados y que sólo el método de determinación de proteínas pudo ser validado. En los estudios llevados a cabo con el aceite de fritura para la elaboración de porras se observó que la bajada de la altura de la cinta de la freidora y la adición conjunta de tocoferoles naturales y palmitato de ascorbilo proporcionaron una mayor vida útil al medio de fritura.Ahmad-Qasem Mateo, MH. (2010). Validación de métodos de análisis de la composición nutricional de frutos secos y estudio de vida útil del aceite empleado en la fritura de porras. http://hdl.handle.net/10251/13660Archivo delegad