Examinando por Autor "Castro , Eulogio"
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Ítem A biorefinery approach to obtain antioxidants, lignin and sugars from exhausted olive pomace(Elsevier, 2021-01-30) Gómez-Cruz , Irene; Contreras Gámez, María del Mar; Romero , Inmaculada; Castro , EulogioExhausted olive pomace (EOP) is the main residue of the pomace olive oil extracting industry. In this work, EOP was fractionated into valuable components for valorisation: an aqueous extract rich in hydroxytyrosol and mannitol, lignins with antioxidant properties and fermentable sugars. EOP was first subjected to water extraction at 85 °C for 90 min. Several pretreatments based on liquid hot water and organosolv with 50% or 60% ethanol (catalysed and uncatalysed with 1% sulfuric acid) were then evaluated in terms of delignification ability and efficiency for enzymatic hydrolysis of the pretreated solids. Once the best conditions had been selected (50 % ethanol-1% sulfuric acid at 130 °C for 60 min), an organosolv lignin (OL) with antioxidant properties was obtained through acid precipitation of the pretreatment liquor. This was compared to the enzymatic hydrolysis lignin obtained in the subsequent step and to the lignins purified by acid hydrolysis. OL showed a higher total phenolic content and antioxidant activity than the rest of the lignin samples. Chemical differences were also observed that could explain the results.Ítem Combined Extraction and Ethanol Organosolv Fractionation of Exhausted Olive Pomace for Bioactive Compounds(Wiley Online Library, 2022-01-25) Gómez-Cruz , Irene; Romero, Inmaculada; Contreras Gámez , María del Mar; Labidi, Jalel; Hernández-Ramos, Fabio; Roseiro, Luisa B.; Duarte, Luis C.; Castro , Eulogio; Carvalheiro, FlorbelaThe olive pomace oil extracting industry generates large amounts of exhausted olive pomace (EOP), a lignocellulosic waste that needs to be managed according to sustainable criteria. The aim of this work is to devise an integrated strategy to valorize EOP by applying two-step extraction, and to evaluate the effect of an ethanol organosolv pretreatment on the delignification and enzymatic hydrolysis of the extracted EOP. Once the extraction and organosolv pretreatment conditions are selected, solubilized lignin is recovered from the pretreatment liquor using different methods. In addition to those organosolv lignin samples, a lignin-rich solid is obtained after enzymatic saccharification of the pretreated solid. All the lignin samples are fully characterized aiming at further valorization. The selected two-step aqueous extraction (85 °C, 90 min, 10% biomass) removes 89% of the extractives content in raw EOP and achieves the full recovery of phenols and mannitol content in that fraction, 4.7 mg gallic acid equivalents per g EOP and 4.5 mg g−1 EOP, respectively. The organosolv pretreatment (50% ethanol catalyzed with 1% H2SO4, 140 °C, 60 min, 15% biomass) results in a delignified solid with 81% of enzymatic digestibility and a high purity organosolv lignin (>71%), rich in guaiacyl units.Ítem Grapevine shoot extract rich in trans-resveratrol and trans-ε-viniferin: evaluation of their potential use for cardiac health(MDPI, 2023-12-02) Contreras Gámez, María del Mar; Feriani , Anouar; Gómez-Cruz , Irene; Hfaiedh, Najla; Harrath, Abdel Halim; Romero, Inmaculada; Castro , Eulogio; Tlili, NizarA grapevine shoot extract (GSE) was obtained using ultrasound-assisted extraction and characterized. The main phenolic constituents were identified as stilbenoids. Among them, trans-resveratrol and trans-ε-viniferin stood out. The GSE was administered to an isoproterenol-induced myocardial injury animal model. The extract alleviated the associated symptoms of the administration of the drug, i.e., the plasma lipid profile was improved, while the disturbed plasma ion concentration, the cardiac dysfunction markers, the DNA laddering, and the necrosis of myocardial tissue were diminished. This effect could be related to the anti-oxidative potential of GSE associated with its antioxidant properties, the increased levels of endogenous antioxidants (glutathione and enzymatic antioxidants), and the diminished lipid peroxidative markers in the heart. The results also revealed angiotensin-converting enzyme (ACE)-inhibitory activity, which indicated the potential of GSE to deal with cardiovascular disease events. This work suggests that not only trans-resveratrol has a protective role in heart function but also GSE containing this biomolecule and derivatives. Therefore, GSE has the potential to be utilized in the creation of innovative functional ingredients.Ítem Lower Energy-Demanding Extraction of Bioactive Triterpene Acids by Microwave as the First Step towards Biorefining Residual Olive Skin(MDPI, 2024-10-09) Gómez-Cruz , Irene; Contreras Gámez , María del Mar; Romero, Inmaculada; Castro , EulogioIn the olive oil industry, a pit fraction is collected from olive pomace and split into a clean pit fraction and a residual olive skin-rich fraction, which does not an industrial application. Therefore, in this work, microwave-assisted extraction (MAE) was applied to obtain high-value triterpene acids (maslinic acid and oleanolic acid) from this biomass using the renewable solvent ethanol. The response surface methodology was used to gain a deeper understanding of how the solvent (ethanol–water, 50–100% v/v), time (4–30 min), and temperature (50–120 °C) affect the extraction performance, as well as the energy required for the process. The effect of milling was also studied and the solid-to-liquid ratio was also evaluated, and overall, a good compromise was found at 10% (w/v) using the raw sample (unmilled biomass). The optimised conditions were applied to residual olive skin sourced from various industries, yielding up to 5.1 g/100 g and 2.2 g/100 g dry biomass for maslinic acid and oleanolic acid, respectively. In conclusion, the residual olive skin is a promising natural source of these triterpene acids, which can be extracted using MAE, releasing extracted solids rich in polymeric carbohydrates and lignin that can be valorised under a holistic biorefinery process.Ítem Optimization of Microwave-Assisted Water Extraction to Obtain High Value-Added Compounds from Exhausted Olive Pomace in a Biorefinery Context(MDPI, 2022-07-06) Gómez-Cruz , Irene; Contreras Gámez, María del Mar; Romero, Inmaculada; Castro , EulogioMicrowave-assisted water extraction (MAWE) was evaluated to obtain the valuable bioactive compounds hydroxytyrosol and mannitol from exhausted olive pomace (EOP). The influence of the operational parameters solid loading (3–15%, w/v), temperature (40–100 °C), and extraction time (4–40 min) was studied using an experimental design. The optimized conditions maximizing their joint extraction were 12% w/v solid loading, 100 °C temperature, and 16 min. It was possible to solubilize 5.87 mg of hydroxytyrosol/g EOP and 46.70 mg mannitol/g EOP. The extracts were also further characterized by liquid chromatography–mass spectrometry, which detected other hydroxytyrosol derivatives such as oleacein, verbascoside, and oleuropein. Moreover, the applied MAWE conditions promoted the co-extraction of proteinaceus material, which was also evaluated. In order to carry out an integral valorization of this waste, the extracted EOP solid was further evaluated chemically and microscopically before recovering the bioactive triterpenes. In particular, maslinic acid and oleanolic acid were obtained, 9.54 mg/g extracted solid and 3.60 mg/g extracted solid, respectively. Overall, MAWE can be applied as a first stage in the fractionation of EOP to support its valorization in a biorefinery framework.Ítem Production of Ethanol from Hemicellulosic Sugars of Exhausted Olive Pomace by Escherichia coli(MDPI, 2020-05-01) López-Linares , Juan Carlos; Gómez-Cruz , Irene; Ruiz, Encarnación; Romero, Inmaculada; Castro , EulogioOlive-derived biomass is not only a renewable bioenergy resource but also it can be a source of bioproducts, including antioxidants. In this study, the antioxidant composition of extracted olive pomace (EOP) and a new byproduct, the residual fraction from olive pit cleaning (RFOPC or residual pulp) was characterized and compared to olive leafy biomass, which have been extensively studied as a source of antioxidants and other bioactive compounds with pharmacological properties. The chemical characterization showed that these byproducts contain a high amount of extractives; in the case of EOP, it was even higher (52.9%) than in olive leaves (OL) and olive mill leaves (OML) (35.8–45.1%). Then, ultrasound-assisted extraction (UAE) was applied to recover antioxidants from the extractive fraction of these biomasses. The solubilization of antioxidants was much higher for EOP, correlating well with the extractives content and the total extraction yield. Accordingly, this also affected the phenolic richness of the extracts and the differences between all biomasses were diminished. In any case, the phenolic profile and the hydroxytyrosol cluster were different. While OL, OML, and EOP contained mainly hydroxytyrosol derivatives and flavones, RFOPC presented novel trilignols. Other compounds were also characterized, including secoiridoids, hydroxylated fatty acids, triterpenoids, among others, depending on the bioresource. Moreover, after the UAE extraction step, alkaline extraction was applied recovering a liquid and a solid fraction. While the solid fraction could of interest for further valorization as a biofuel, the liquid fraction contained proteins, sugars, and soluble lignin, which conferred antioxidant properties to these extracts, and whose content depended on the biomass and conditions applied.Ítem Recovery of Bioactive Compounds from Industrial Exhausted Olive Pomace through Ultrasound-Assisted Extraction(MDPI, 2021-06-10) Gómez-Cruz , Irene; Contreras Gámez, María del Mar; Carvalheiro, Florbela; Duarte, Luis C.; Roseiro , Luisa B.; Romero , Inmaculada; Castro , EulogioExhausted olive pomace (EOP) is the main agro-industrial waste of the olive pomace extracting industries. It contains phenolic compounds and mannitol, so the extraction of these bioactive compounds should be considered as a first valorization step, especially if EOP is used as biofuel. Therefore, EOP was subjected to bath-type ultrasound-assisted extraction (UAE), and the effects of the acetone concentration (20–80%, v/v), solid load (2–15%, w/v), and extraction time (10–60 min) on the extraction of antioxidant compounds were evaluated according to a Box–Behnken experimental design. By means of the response surface methodology, the optimum conditions were obtained: 40% acetone, 8.6% solids, and 43 min. For all the extracts, the total phenolic content (TPC), flavonoid content (TFC), and antioxidant activity (DPPH, ABTS, and FRAP) were determined. With the aim of shortening the extraction time, a two-level factorial experiment design was also carried out using a probe-type UAE, keeping the solid load at 8.6% (w/v) and the acetone concentration at 40% (v/v), while the amplitude (30–70%) and the extraction time (2–12 min) were varied to maximize the aforementioned parameters. Finally, a maximum of phenolic compounds was reached (45.41 mg GAE/g EOP) at 12 min and 70% amplitude. It was comparable to that value obtained in the ultrasonic bath (42.05 mg GAE/g EOP), but, remarkably, the extraction time was shortened, which translates into lower costs at industrial scale. Moreover, the bioactive compound hydroxytyrosol was found to be the major phenolic compound in the extract, i.e., 5.16 mg/g EOP (bath-type UAE) and 4.96 mg/g EOP (probe-type UAE). Other minor phenolic compounds could be detected by capillary zone electrophoresis and liquid-chromatography–mass spectrometry. The sugar alcohol mannitol, another bioactive compound, was also found in the extract, and its content was determined. Thus, the use of this technology can support the valorization of this waste to obtain bioactive compounds, including mannitol, hydroxytyrosol, and other derivatives, before being applied for other uses.Ítem Strategies for the purification of hydroxytyrosol-rich extracts obtained from exhausted olive pomace(Elsevier, 2023-11-15) Gómez-Cruz , Irene; Contreras Gámez , María del Mar; Romero, Inmaculada; Ribeiro, Belina; Roseiro, Luisa B.; Duarte, Luis C.; Carvalheiro, Florbela; Castro , EulogioExhausted olive pomace (EOP) is a residual biomass from which hydroxytyrosol can be recovered. This compound has applications in the food/pharma sectors, but its extraction yields complex extracts that require further purification for some applications. This work explores purification strategies based on membrane technology, liquid–liquid extraction (LLE), and solid-phase extraction with adsorbents and resins. The hydroxytyrosol content, phenolic profile, antioxidant activity, and inhibition of α-glucosidase and α-amylase were monitored. Hydroxytyrosol stood out in all purified extracts. The best hydroxytyrosol recovery (88.8%) was achieved using LLE with ethyl acetate as the extractant, while the purest extracts in phenolic compounds, including hydroxytyrosol, were obtained using the latter solvent and C18 (529 mg/g), DSC-8 (873 mg/g), and Purosorb PAD910 (523 mg/g). Conversely, mannitol and glucose, at high concentrations in the extract, were selectively retained in the aqueous phases. The developed strategies are discussed regarding their suitability to provide hydroxytyrosol-concentrated extracts, up to 291 mg/g, with antioxidant and antidiabetic functionalitiesÍtem Towards the Integral Valorization of Olive Pomace-Derived Biomasses through Biorefinery Strategies(Wiley Online Library, 2024-01-24) Gómez-Cruz , Irene; Contreras Gámez , María del Mar; Romero, Inmaculada; Castro , EulogioThe olive oil sector generates a high quantity of biomasses every year, especially in the Mediterranean region. Olive pomace is the main one, but depending on the extraction and subsequent processing, other derived biomass by-products are generated like pâté, exhausted olive pomace, olive stone, and residual pulp. Their sustainable valorization is crucial. Therefore, this review first conceptualizes the current situation of the olive oil sector and describes these biomasses from a qualitative and quantitative point of view. Second, information on the bioactive compounds they present, the technologies used for their extraction, and examples of applications for their extracts is provided. Third, since the extraction of bioactive compounds will generate new residual biomasses, this review takes a step forward by integrating the extraction step in biorefinery cascading schemes. It also analyzes the benefits of this integration, the contribution to a circular (bio)economy, and the achievement of sustainable development goals.Ítem Ultrasound-Assisted Extraction as a First Step in a Biorefinery Strategy for Valorisation of Extracted Olive Pomace(MDPI, 2019-07-12) Martínez-Patiño , José Carlos; Gómez-Cruz , Irene; Romero , Inmaculada; Gullón, Beatriz; Ruiz, Encarnación; Brnčić , Mladen; Castro , EulogioCurrently, interest in finding new feedstock as sources of natural food antioxidants is growing. The extracted olive pomace (EOP), which is an agro-industrial residue from the olive pomace extracting industries, is generated yearly in big amounts, mainly in the Mediterranean countries. EOP was subjected to an ultrasound assisted extraction with ethanol-water mixtures. The effect of main parameters, such as ethanol concentration (30–70% v/v), ultrasound amplitude (20–80%), and extraction time (5–15 min), on the extraction of antioxidant compounds was evaluated according to a Box–Behnken experimental design. The antioxidant capacity of the resulting extracts was determined by measuring their content in total phenolic compounds (TPC) and flavonoids (TFC), as well as their antioxidant activity by DPPH, ferric reducing antioxidant power (FRAP), and ABTS assays. Considering the simultaneous maximization of these five responses, the optimal conditions were found to be 43.2% ethanol concentration, 70% amplitude, and 15 min. The ultrasound assisted extraction of EOP under these optimized conditions yielded an extract with a phenolic and flavonoid content (per gram of EOP) of 57.5 mg gallic acid equivalent (GAE) and 126.9 mg rutin equivalent (RE), respectively. Likewise, the values for DPPH, ABTS, and FRAP assay (per gram of EOP) of 56.7, 139.1, and 64.9 mg Trolox equivalent, respectively were determined in the optimized extract.Ítem Valorisation of Exhausted Olive Pomace by an Eco-Friendly Solvent Extraction Process of Natural Antioxidants(MDPI, 2020-10-17) Gómez-Cruz , Irene; Cara, Cristóbal; Romero , Inmaculada; Castro , Eulogio; Gullón , BeatrizExhausted olive pomace (EOP) is the waste generated from the drying and subsequent extraction of residual oil from the olive pomace. In this work, the effect of different aqueous solvents on the recovery of antioxidant compounds from this lignocellulosic biomass was assessed. Water extraction was selected as the best option for recovering bioactive compounds from EOP, and the influence of the main operational parameters involved in the extraction was evaluated by response surface methodology. Aqueous extraction of EOP under optimised conditions (10% solids, 85 °C, and 90 min) yielded an extract with concentrations (per g EOP) of phenolic compounds and flavonoids of 44.5 mg gallic acid equivalent and 114.9 mg rutin equivalent, respectively. Hydroxytyrosol was identified as the major phenolic compound in EOP aqueous extracts. Moreover, these extracts showed high antioxidant activity, as well as moderate bactericidal action against some food-borne pathogens. In general, these results indicate the great potential of EOP as a source of bioactive compounds, with potential uses in several industrial applications.