IPP - Comunicaciones a congresos, conferencias, etc.Ingeniería de Procesos a Presión - Comunicaciones a congresos, conferencias, etc.https://uvadoc.uva.es/handle/10324/230432024-03-29T15:33:44Z2024-03-29T15:33:44ZBiomass hydrothermal fractionation modelling at lab and pilot scales kinetics & mass transferCabeza Sánchez, ÁlvaroHu, XihuaReynolds, WienkeSobrón Grañón, FranciscoSmirnova, IrinaGarcía Serna, Juanhttps://uvadoc.uva.es/handle/10324/351912021-06-24T07:29:36Z2018-01-01T00:00:00ZHydrothermal fractionation is a well-known process for lignocellulosic biomass upgrading. It is based on the continuous treatment of biomass with hot pressurized water, converting the biomass major components (hemicellulose, cellulose and lignin) into soluble compounds. Thus, it is one of the most promising options to produce chemicals and energy from biomass since it only requires water and temperature. However, it is a highly complex process that involves a great deal of physical phenomena: biopolymer and oligomer cleavage, sugar production and degradation, acid releasing, homogeneous acid catalysis, solid-liquid mass transfers and porosity changes. For this reason, the development of a comprehensive kinetic model for biomass hydrothermal fractionation is a difficult matter. Despite these burdens, several modelling options that go from the simplest option, a first order kinetic model, to deeper and complete studies, can be found in the literature. These models are able to reproduce the experimental data of different biomasses in both, packed bed and batch reactors. Nonetheless, they are generally used for just one reactor or for one specific biomass, like spruce or wheat bran. Thereby, this work was aimed at developing an overall model for hemicellulose extraction, validating it with data from different packed bed reactors and for completely different biomasses. Additionally, this model included the whole set of physical phenomena. So, a novel reaction path way with all the physico-chemical process involved in the both phases, the liquid and the solid, was proposed. The model was obtained applying a mass balance for each compound in this mechanism and it was solved applying advanced numerical methods (orthogonal collocation over finite elements and Runge-Kutta with 8th order of convergence). Regarding kinetics, auto-catalytic expressions were selected since they have been demonstrated to be a suitable option to simulate quick changes in concentration profiles. On the other hand, the data of the hydrothermal fractionation were taken from 4 different reactors and using 3 biomasses (holm oak, wheat straw and catalpa) were used (0.1, 3, 6 and 40L). The temperature range was between 140 ºC and 215 ºC to focus the study on the hemicellulose extraction and the residence time was fixed around 5 min to promote extraction without degrading the hydrolysate. The model reproduced the experimental behaviour with average deviations between 6 and 50%. It is worth mentioning that the higher deviations were obtained when also the uncertainty of the experimental measure of the compounds was high. The simulated profiles included: oligomers, hexoses, pentoses, acetic acid, degradation products and pH. Furthermore, it is worth mentioning that the fractionation was mainly controlled by the soluble oligomers production and their hydrolysis kinetics. Therefore, it could be concluded that, for the cases studied, if temperature and pH profiles inside two different reactors are similar, their global behaviour will be also the same, independently of the biomass studied and reactor properties. Finally, it should be remarked that all the calculated parameters had physical meaning.
2018-01-01T00:00:00ZMicrowaves and subcritical water for the process intensification of ferulic acid recovery from wheat branPazo Cepeda, María VictoriaAlonso Sánchez, Gloria EstherCocero Alonso, María Joséhttps://uvadoc.uva.es/handle/10324/351842021-07-06T08:34:33Z2017-01-01T00:00:00ZWheat bran is an important by-product of the cereal milling industry and it has a great potential as raw material in a biorefinery. Wheat bran contains many important bioactive phenolic compounds, such as ferulic acid (FA), phytic acid, caffeic acid and flavonoids that can be recovered in a first step of a cereal biorefinery to increase economical benefit of the whole process. FA is the most abundant phenolic acid in the wheat bran, and it exhibits a number of potential applications such as natural antioxidant, food preservative/antimicrobial agent, anti-inflammatory agent, photoprotectant, and as precursor of vanillin (food flavor). FA seems to be part of the cell wall bounded via ester linkages to the structural polysaccharides, while dimers of ferulic acid can serve to cross-link hemicelluloses. Ferulic acid is unstable and can be oxidized in high temperature and it could be denature and reduced by using alkaline-hydrolysis. Release of FA from plant material is typically facilitated by alkaline and enzymatic hydrolysis. Alkaline-hydrolysis cannot be considered a green technology, is poorly selective and solvent consuming. Enzymatic-hydrolysis requires cocktails of enzymes (amylases, xylanases, proteases, feruloyl esterases) combined with bran pre-treatment and exhibits economical drawbacks and low extraction yield per unit of enzyme. The challenge is, therefore, to intensify the process by using green and short time techniques with high hydrolysis capacity to recover selectively the maximum amount of free FA and preserving the antioxidant activity of the extract.
In this work, we present and discuss a strategy to maximize the recovering of free FA from wheat bran by using microwaves and subcritical water. This study presents the effect of various factors in a Microwave-Assisted-Extraction (MAE) with water: time, temperature and solvent/solid ratio, using Box-Benhken experimental design. MAE of wheat bran at 220ºC and 1 minute leads to the recovery of ca. 80% of the FA, that is a really high yield compared to that reported in the literature for enzymatic hydrolysis (15-35%) [1]. However, more than 70% of FA remains bounded to the cell compounds extracted under such conditions. Subcritical water in the range has been evaluated to complete the release of free FA. Temperatures in the range 250-320 ºC and time from 1 to 10 min have been studied at 150 barg and discussed using the severity factor. Under such conditions dissociation of water is very important, and hydroxyl groups act to the ester bond breakage. Results are discussed in terms of total FA extraction yield, Free FA extraction yield, TOC and total phenolic content and antioxidant capacity of the final hydrolysate.
2017-01-01T00:00:00ZRu-supported on mesoporous silica as active catalyst for the hydrolysis of the hemicellulosic fraction of wheat branSánchez Bastardo, NuriaAlonso Sánchez, Gloria Estherhttps://uvadoc.uva.es/handle/10324/351512021-07-06T08:34:33Z2017-01-01T00:00:00ZExtraction and Hydrolysis of arabinoxylans have been studied using RuCl3 catalysts over different mesoporous silica supports. Acidity of the catalyst is a key parameter for these processes: the higher the Acidity, the higher the Yield.
Ru+3 has demonstrated to be active, as it is a moderate Lewis acid. Arabinose is always faster released than xylose: Arabinose belongs to side chains and it is linked by beta-glycosidic bonds (weak). Xylose belongs to the backbone and it is linked by β -glycosidic bonds (strong).
2017-01-01T00:00:00ZProducción de alcoholes C5 y C6 con catalizadores Ru/ZrO2 soportados en MCM48Aspromonte, Soledad GuadalupeSanz, OihaneBoix, Alicia VivianaMontes, MarioAlonso Sánchez, Gloria Estherhttps://uvadoc.uva.es/handle/10324/351162021-07-06T08:34:33Z2018-01-01T00:00:00ZSe utilizaron catalizadores de Ru/ZrO2 soportados en soportes mesoporosos del tipo MCM48 en la hidrogenación catalítica de glucosa, xilosa y arabinosa para la obtención de sus respectivos alcoholes (sorbitol, xilitol y arabitol). Mediante adsorción/desorción de N2 a -196ºC se determinó que los materiales poseen áreas superficiales y volumenes de poro que oscilan entre 1099-854 m2/g y 0,899-0,616 cm3/g, respectivamente. Por medio de SAXS se observó que el ordenamiento mesoporoso se mantiene luego de incorporar rutenio y/o zirconia. Las fases activas depositadas fueron RuO2 y ZrO2 en los catalizadores calcinados. Se detectó la presencia de partículas metálicas Ru(0), al reducir los catalizadores en flujo de H2 a 200 ºC.
El catalizador bimetálico RuZrM reducido presentó una capacidad de producción de arabitol y xilitol (C5) de 76,2 % y de sorbitol (C6) de 68,3 %, lo cual indica un incremento respecto del catalizador comercial (Ru/C). El agregado de ZrO2 no inhibe la actividad de hidrogenación del rutenio metálico.
2018-01-01T00:00:00ZFraccionamiento catalítico de hemicelulosas de salvado de trigo en agua caliente presurizadaSánchez Bastardo, NuriaAlonso Sánchez, Gloria Estherhttps://uvadoc.uva.es/handle/10324/351152021-07-06T08:34:33Z2018-01-01T00:00:00ZEl salvado de trigo es un subproducto de la molienda de granos de trigo. Se producen alrededor de 150 millones de toneladas por año en todo el mundo y su uso principal es como un componente de bajo valor en alimentos para animales. La composición general del salvado de trigo es la siguiente: agua (12.1%), proteínas (13.2 - 18.4%), grasas (3.5 - 3.9%), almidón (13.8 - 24.9%), celulosa (11.0%), arabinoxilanos (10.9 - 26.0%), β-glucanos (2.1 - 2.5%), ácidos fenólicos (0.02 - 1.5%) y ceniza (3.4 - 8.1%)1. Los arabinoxilanos (AX) pertenecen a la parte hemicelulósica de la biomasa y están compuestos por una cadena principal de residuos de D-xilopiranosilo unidos por enlaces β-1,4. La abundancia de arabinoxilanos en el salvado de trigo los hace susceptibles de ser extraídos y convertidos en diferentes productos químicos intermedios o finales de alto valor añadido tales como furfural, ácido succínico, xilitol, arabitol, entre otros.
Los catalizadores de sílice mesoporosa han demostrado ser una buena opción para la hidrólisis de arabinoxilanos del salvado de trigo. En este trabajo, se obtiene un alto rendimiento de hidrólisis de arabinoxilanos en los monómeros correspondientes (94 y 96% para xilosa y arabinosa, respectivamente) a 180 ºC después de 15 minutos usando una cantidad de RuCl3/Al-MCM-48 igual a 4.8 g·g-1. Nuestros resultados demostraron que los azúcares monoméricos C5 se pueden maximizar utilizando un proceso de dos pasos que consiste en un fraccionamiento hidrotermal de arabinoxilanos y su posterior hidrólisis utilizando RuCl3/Al-MCM-48 y 180 ºC en ambos pasos, y un tiempo total de 25 minutos2.
2018-01-01T00:00:00ZMaximization of C5 sugars from wheat bran over heterogeneous catalystsSánchez Bastardo, NuriaAlonso Sánchez, Gloria Estherhttps://uvadoc.uva.es/handle/10324/351142021-07-06T08:34:33Z2017-01-01T00:00:00ZThe production of C5 sugars from wheat bran has been optimized in a two-step process consisting of a hydrothermal fractionation of AX and their subsequent hydrolysis using RuCl3/Al-MCM-48. From the fractionation step, almost 80% of the AX were solubilized into the aqueous phase. After the hydrolysis process, a high hydrolysis yield of xylo- and arabino- oligosaccharides into xylose (94%) and arabinose (96%), respectively, has been achieved. Ru+3, as a moderate Lewis acid, has demonstrated to be active in the fractionation and hydrolysis processes of the hemicellulosic part of wheat bran.
2017-01-01T00:00:00ZCellulose hydrolysis using Ag exchanged in mesoporous mordeniteAspromonte, Soledad GuadalupeRomero, AlbertoBoix, Alicia VivianaAlonso Sánchez, Gloria Estherhttps://uvadoc.uva.es/handle/10324/351132021-07-06T08:34:33Z2017-01-01T00:00:00ZThis work presents the study of catalysts based on Ag exchanged in mesoporous mordenite used to complete the hydrolysis of oligomers derived from the solubilization of cellulose in supercritical water. The synthesized mesoporous zeolitic support showed a significant increase in pore volume and size in comparison to the original zeolite. The incorporation of Ag did not significantly modify the pore size, which allows the voluminous oligomer molecules to reach the active centers. By means of characterization techniques, the presence of Ag (I) ions in interaction with the structure was detected. Through adsorption and desorption of NH3 it was determined that silver species favor the formation of strong acid sites. During the exchange of Na (I) by Ag (I) ions are also produced protons H+ (acid medium) which are located in the network and confer moderate acidic character. The combination of a mesoporous zeolite with Ag (I) ions allowed almost complete hydrolysis of the cellulose (81.8%) with a yield of glucose of 43.5%. Thus, the presence of Ag modified the acid-base properties improving the hydrolysis of cellulose.
2017-01-01T00:00:00ZSupercritical Impregnation in Carboxylated Based MOFs.Monteagudo, RebecaRodríguez Rojo, SorayaCoronas, JoaquinCocero Alonso, María Joséhttps://uvadoc.uva.es/handle/10324/314582021-06-24T07:29:21Z2017-01-01T00:00:00ZMetal-Organic Frameworks (MOFs) are porous materials made of metal clusters connected by organic linkers, typically dicarboxylate ligands. These materials have been intensively studied in recent years due to the distinctive properties such as high surface area, surface functionalization and structural flexibility for some of them. The potential applications are broad in fields such as catalysis, separations or drug delivery.[1]
The supercritical CO2 (sc-CO2) has been recently used to activate MOFs, i.e. the removal of the excess of ligand and solvent from the pores, in substitution of procedures like calcination which can damage the crystallinity. Through this technology the highest surface area has been reported, around 7000 m2/g.[2] Therefore supercritical fluids seem to be of potential interest in MOFs processing. In our case we have tested the impregnation with supercritical CO2 in MOFs, in opposition to liquid impregnation which requires post processing steps, as separation and drying of the material.
2017-01-01T00:00:00ZEvaluation of cosmetic activity of optimized anthocyanin extracts from different wine leesRomero Díez, RutMatos, MelanieBronze, Maria RosarioRodríguez Rojo, SorayaCocero Alonso, María JoséMatias, Ana A.https://uvadoc.uva.es/handle/10324/314572021-06-24T07:29:17Z2018-01-01T00:00:00ZWine lees (WL), a winery residue produced during fermentation, are a rich source of high value compounds such as polyphenols. Among polyphenols, anthocyanins (AC) are the most abundant compounds found in grapes and residues derived from the vinification process. The recovery of these natural colorants (AC) from WL has attracted much attention in recent years due to studies showing that the concentration of AC in WL is 10 times higher than in grape skins. AC have a special impact in alimentary, cosmetic and pharmaceutic industries due to their antioxidant, antimicrobial and/or anticarcinogenic properties. Additionally, the exploitation of these dregs leads to a sustainable growth of the wine industry.
Thus, this work aims to develop effective green extraction processes for the selective recovery of bioactive compounds, namely AC, from WL from first fermentation of red wine and Port wine. The influence of extraction parameters in conventional solid-liquid (S-L) extraction was studied and results show that the best conditions were a mixture of 50:50 (v/v) EtOH:H2O as the extraction solvent, a S-L ratio of 0.1 g/mL and a temperature of 25oC. Besides, microwaves (MW) were applied as pretreatment to intensify the extraction of AC, leading to a significant improvement in the extraction yield (from 3.04 ± 0.03 mg malvidin equivalents (MLVE)/g dry lees (DL) to 4.45 ± 0.30 mg MLVE/g DL) as well as a substantial reduction in the extraction time (from 10 min to 90 s). Further, the cosmetic potential of WL conventional extracts and extracts obtained following MW pretreatment was evaluated. Antioxidant activity was evaluated by chemical assays (ORAC/HOSC/HORAC) and cell-based assays using keratinocytes (HaCaT) and fibroblasts (HFF). Inhibitory capacity of WL extracts towards enzymes relevant for skin ageing, such as tyrosinase, elastase and MMP-1, was also assessed. Red wine lees extract had the highest phenolic content, and therefore presented the highest antioxidant capacity. Also, this WL extract effectively inhibited enzymatic activities. Main phenolic compounds were identified by HPLC-DAD-MS and AC were shown to play a significant role in the bioactivity of WL extracts.
2018-01-01T00:00:00ZGreen “grape stems” biorefinery: polyphenols and hemicellulose extractionRomero Díez, RutRubio, JoanaMatos, MelanieMatias, Ana A.Cocero Alonso, María JoséRodríguez Rojo, Sorayahttps://uvadoc.uva.es/handle/10324/314562021-06-24T07:29:16Z2018-01-01T00:00:00ZGrape stems (GS) are winery wastes that belong to the vinification process. They could represent an environmental problem if they are not treated in a correctly way. Due to its high content on stilbenes and flavonoids, GS can be considered as a polyphenolic-rich by-product. The attraction paid to these type of compounds has widely increased as a result of their antioxidant, antimicrobial and/or anticarcinogenic properties.
In a first approach, GS were valorized in terms of polyphenols extraction using, two different methodologies. Firstly, solid-liquid extraction parameters of polyphenols from GS have been studied: solid-liquid ratio (RS-L), type of solvent (variation of the percentage of ethanol in the hydroalcoholic mixture) and temperature (T). Parameter values selected as the best for conventional polyphenol extraction were: a RS-L of 0.10 g/mL, a T of 75°C and a hydroalcoholic mixture of 50% vol. ethanol. Secondly, microwaves were applied to GS as a pre-treatment of conventional extraction. In this case, the varied parameters were RS-L, type of solvent and the time of the pre-treatment. For this purpose, a statistical surface design was applied to get the optimum conditions which maximize the final TPC of the extracts. Extracts were characterized in terms of total polyphenol content (TPC) and total flavonoid content (TFC). Stilbenes were quantified by HPLC-DAD analysis. Antioxidant capacity of the extracts was measured via Oxygen Radical Absorbance Capacity (ORAC).
Furthermore, TPC and TFC extraction yields from GS were fitted by a linear driving force model in order to obtain mass transfer parameters (deviation lower than 10%) to analyse the process from a theoretical point of view.
In a second approach, since GS is a residual woody material, the co-extraction of hemicelluloses and polyphenols with pressurized water was studied. Hemicelluloses are branched polymers of different monosaccharides, being xylan the most abundant, in this case. This biopolymer has potential applications in drug delivery and active packing, among others. The influence of temperature (120 – 160°C) in the extraction yield was analysed.
2018-01-01T00:00:00ZValorization of wine lees residues into valuable products via Supercritical Water Hydrolysis.Romero Díez, RutRodríguez Rojo, SorayaMatias, Ana M.Cocero Alonso, María Joséhttps://uvadoc.uva.es/handle/10324/314552021-06-24T07:29:20Z2017-01-01T00:00:00ZWine lees are water-waste residues generated during maceration and fermentation steps of the vinification process and they constitute a source of high value compounds, such as polyphenols, mainly anthocyanins (AC). The exploitation of these dregs could contribute to the development of new wine-related products and could also lead to a sustainable growth of the wine industry due to the concentration of AC is 10 times higher in wine lees than in grape skins [1]. After the recovery of the polyphenols from wine lees, a wet solid waste remains with poor chemical potential. This residue can be recycled by a hydrolysis step. Supercritical water (SCW) has proved to be a suitable environment-friendly media for biomass hydrolysis due to its unique properties, such as a high diffusivities or low dielectric constant [2]. This hydrolysis produces a liquid product rich in sugars that can be used as feed in a fermentation step afterwards. However, the yield of this last step would be lower with wine lees than with conventional biomasses since its cellulosic fraction only constitutes 18%.
The main objective of the hydrolysis of the wine lees residue is to obtain reduced sugars which are essential chemical building blocks in the so-called biorefinery cycle. A continuous pilot plant was used to carry out the hydrolysis of wine lees in SCW. This facility was based on a continuous reactor with instantaneous heating and cooling that allowed precise control of the reaction time and therefore, high recovery of sugars was achieved and avoiding sugar degradation reactions. A wine lees-water suspension (10% w/w) was continuously fed to the reactor using a pump at a flow rate of 1 kg/h and processed under 380-395ºC and 25MPa at different reaction times, between 0.056 and 0.076s. A brown liquid was obtained after the hydrolysis step, rich in hexoses (yield of 50%) such as cellobiose, glucose and fructose. It was also observed that increasing the reaction time and temperature favored the degradation of the recovered sugars into pyruvaldehyde and glycolaldehyde.
2017-01-01T00:00:00ZWine lees valorization: Pretreatment effect on anthocyanin extraction kinetics from different wine lees.Romero Díez, RutRodrigues, LilianaRodríguez Rojo, Sorayahttps://uvadoc.uva.es/handle/10324/314542021-06-24T07:29:18Z2017-01-01T00:00:00ZWine industry generates huge amounts of wastes and by-products, which are sources of high value compounds; including vine prunings, grape stalks, grape pomace and wine lees. For instance, anthocyanin (AC) extraction from grape pomace is a well-known process and several works can be found in literature. Similarly, wine lees (water-waste residues generated during maceration and fermentation steps) have been used to obtain tartaric acid or as a food supplement for animals. Additionally, the recovery of natural colorants (AC) from these waste streams has attracted much attention in the last years due to recent studies showed that the concentration of these colorants are 10 times higher than in grape skins. Thereby, the exploitation of these dregs could constitute to the development of new wine-related products and could also lead to a sustainable growth of the wine industry.
As a result, this work is focused on the development of effective green strategies and processes for the selective recovery of bioactive compounds from different wine lees of the first and second fermentation. Microwave (MW), sonication (S) and enzymatic (EM) pre-treatments followed by a solid-liquid extraction have been studied to intensify the extraction of AC in comparison with the conventional extractions
2017-01-01T00:00:00ZUsing microwaves as a pre-treatment for enhancing the extraction of polyphenols from grape stemsRomero Díez, RutRubio, JoanaMatias, Ana A.Cocero Alonso, María JoséRodríguez Rojo, Sorayahttps://uvadoc.uva.es/handle/10324/314532021-06-24T07:29:15Z2018-01-01T00:00:00ZGrape stems are a residual woody material from the vinification process. A waste that, if it is not treated in a correctly manner, could represent an environmental problem. Moreover, in the last years, special attention has been paid to this waste due to its high content of polyphenols, mainly stilbenes and flavonoids. Several studies have already revealed the potential and possibilities of these compounds in industries, such as alimentary, cosmetic and pharmaceutic thanks to their antioxidant, antimicrobial and/or anticarcinogenic properties. In this work, the effect of solid-liquid extraction parameters of polyphenols from grape stems have been studied. These parameters were: solid-liquid ratio (RS-L), type of solvent (variation of the percentage of ethanol in the hydroalcoholic mixture) and temperature. Parameter values selected as the best for polyphenol extraction in a conventional solid-liquid extraction were: a RS-L of 0.10 g/mL, a temperature of 75ºC and a hydroalcoholic mixture with a 50% vol. of ethanol. Furthermore, microwaves were applied to grape stems as a pre-treatment prior to the conventional extraction for the first time. In this case the parameters assessed were also solid-liquid ratio, type of solvent and, in addition, the time of the pre-treatment. For this purpose, a statistical surface design was employed to obtain the optimum conditions which maximize the final TPC of the extracts. In a first approach, extracts were characterized in terms of total polyphenol content and total flavonoid content. The main result was that, microwaves make it faster the extraction (until 4 times) but it is not clear their role on the extraction yield.
Key-words. Grape stems, stilbenes, flavonoids, microwave
2018-01-01T00:00:00ZMicrowave pretreatment for the extraction of active compounds from olive pomace. Extraction optimization and dielectric propertiesÁlvarez Martín, AnaCocero Alonso, María JoséMato Chaín, Rafael Bartoloméhttps://uvadoc.uva.es/handle/10324/313302023-04-26T10:44:44Z2018-01-01T00:00:00ZOlive pomace is a waste of the olive industry, with little use as a by-product. However, its high content in active compounds, like oleocanthal, hydroxytyrosol or oleuropein, makes this material a source of valuable bioactive extracts in food and health industry. Some of these compounds are highly bounded to the biomass structure, what entails the use of severe hydrothermal conditions (for instance, 180ºC for 90 minutes) or non-edible solvents (such as benzene and hexane). Accordingly, conventional solid-liquid extraction of polyphenols from olive pomace presents yet severe drawbacks to overcome. A short and intense microwave pretreatment is presented in this work as a greener effective resolution to enhance yield, final product quality and throughput capacity.
Two pretreatments have been tested: an atmospheric-microwave one, which provided enough energy to reach the solvent boiling point, and a pressurized-microwave pretreatment, where a pressure of 3 bars was reached. Both pretreatments were followed by a conventional solid-liquid extraction that was also used by itself as a reference to assess the efficiency changes associated to the pretreatments.
Although extraction yield (mgGAE/gDry pomace) is not highly enhanced with the addition of the pretreatments, extraction richness is. Extraction richness (mgGAE/gDry Extract) is understood as the proportion of active compounds in the possible commercial final product. This is usually a solid product, since de solvent must be removed from the extract to obtain a stable dry product. A 47% and a 39% richer extracts are obtained with the pressurized and atmpspheric microwave pretreatments, respectively. It is also noteworthy the high proportion of hydroxytyrosol obtained when pretreatments are used. The implementation of the pretreatment provides an improvement in the extraction of this compound, since a 3-fold richer extract in this compound is attained. This enhancement is also found in the antioxidant capacity of the extract, which is around 30% higher in the pretreated process than in the standalone conventional solid-liquid extraction.
Such enhancements support the scale-up of the process. To achieve this goal, the dielectric properties of the complex mixture water-ethanol-pomace have been measured under microwave heating as a function of temperature. Data has also been correlated to a model able to predict multiphase mixture permittivity. The resulting model is able to estimate the dielectric constant with an accuracy of 12%, and the loss factor with a deviation of 36%. These preliminary results will be used in the near future to adapt and operate a continuous microwave extraction oven to explore the possibilities of its utilization in a real processing plant.
2018-01-01T00:00:00ZContinuous microwave processing of olive-pomace for active compounds recoveryÁlvarez Martín, AnaCocero Alonso, María JoséMato Chaín, Rafael Bartoloméhttps://uvadoc.uva.es/handle/10324/313282023-04-26T10:45:36Z2018-01-01T00:00:00ZMicrowave assisted extraction of natural products has been studied over the past decades as an alternative process for high-value bioactive compounds. The main advantages claimed for this technique are high extraction rates, high extraction yields and low degradation. Despite the high number of publications on this topic, most of them are considered only for analytical purposes, and only a few ones are studied for industrial implementation.
Olive-oil industry produces a by-product that corresponds to the residue of the olive-pulp after the first press, known as olive-pomace. This is a low-value residue, mainly to produce olive-pomace oil, but the price paid for this by-product barely covers the cost of transport. However, olive-pomace has a high content of active compounds (hydroxytyrosol, oleuropein…) that make it valuable for the extraction of bioactives. Most of the recovery methods reported in literature make use of high temperature conditions, which can degrade some thermolabile compounds, or use non-authorized solvents for foodstuffs purposes (benzene, hexane…).
In this work a microwave assisted extraction pretreatment has been developed to enhance the extraction recovery of bioactive compounds from this residue, while reducing the residence time for extraction. Operating conditions are initially studied in a laboratory microwave oven. The analysed operating variables were material/solvent ratio and specific energy. Microwave pretreatment is followed by a fast conventional solid-liquid extraction process. Extraction kinetics are determined not only for polyphenol content or specific compounds, but also for the total solid extract residue. This way, in addition to recovery, also the richness of the final dry product can be optimized to obtain simultaneous maximum extraction yield and final product concentration. Extraction richness (mgGAE/gDry Extract) may be improved more than 40% by this technique, compared to conventional extraction processes.
2018-01-01T00:00:00ZPressurized Water Extraction and Supercritical Water Hydrolysis as means to obtain Ferulic Acid from Wheat BranPazo Cepeda, María VictoriaCocero Alonso, María JoséAlonso Sánchez, Gloria Estherhttps://uvadoc.uva.es/handle/10324/235012021-06-24T07:29:12Z2016-01-01T00:00:00ZPhenolic compounds are of considerable interest due mainly to their antioxidant
activity. They constitute a large family of compounds that can be found in cereals, fruits
or vegetables, and present potential commercial applications in the food, health and
cosmetic industries. By extracting them from waste materials, we are contributing not
only to reduce but also to revalorize the residues.
Wheat bran is an abundant and underused byproduct from the milling industry,
whose main phenolic compound is ferulic acid (FA). It can be found in three forms:
soluble free (F-FA), soluble conjugated (C-FA) and insoluble bound form (B-FA), being
the major part in the insoluble bound form, esterified to the arabinoxylans (AX) and
other cell wall structural components (≈92%). Hence, new processes are required to
break these bonds in order to recover it in high quantities.
In this study, two different techniques have been applied and compared with the
aim of maximizing the extraction of FA from wheat bran: in the first one pressurized
water (PW) is used as solvent and in the second one supercritical water (SCW) has
been tested.
2016-01-01T00:00:00Z