Persona: Monago Maraña, Olga
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Publicación Second-order calibration in combination with fluorescence fibre-optic data modelling as a novel approach for monitoring the maturation stage of plums(Elsevier, 2020-04-15) Domínguez Manzano, Jaime; Muñoz de la Peña, Arsenio; Durán Merás, Isabel; Muñoz de la Peña, Arsenio; Monago Maraña, OlgaIn this work, non-destructive autofluorescence of plums was employed to study the chlorophylls’ concentration evolution along the maturation process. For that, excitation-emission matrices (EEMs), containing full fluorescence information, were collected with a fibre-optic, assembled to a spectrofluorometer. Data analysis was performed with several second-order multi-way algorithms, such as parallel factor analysis (PARAFAC), multi-way partial least-squares (N-PLS), unfolded partial least-squares (U-PLS), and multivariate curve resolution-alternating least-squares (MCR-ALS). Firstly, the EEMs of each plum, collected each week along the maturation process, were processed with PARAFAC. Two components were used to model the data and the excitation and emission loadings were obtained. Score values for the first PARAFAC component showed a clear evolution with time, increasing during the first five weeks, and decreasing for the last weeks. Also, the chlorophyll concentrations obtained by HPLC analysis, in the skin and the whole fruit, were compared with those obtained with different algorithms mentioned before. Best results were obtained in the case of skin for all algorithms. Similar correlation coefficients (r) were obtained in all cases (0.899 (PARAFAC); 0.940 (U-PLS); 0.936 (N-PLS) and 0.958 (MCR-ALS)). When the elliptical joint confidence region (EJCR), for the slope and intercept, were calculated, the theoretically expected values of 1 and 0, for the slope and intercept, respectively, were included in all ellipses. However, it was observed that for the skin data and U-PLS and N-PLS algorithms, the EJCR confidence region was smaller than in the other cases.Publicación First-order discrimination of methanolic extracts from plums according to harvesting date using fluorescence spectra. Quantification of polyphenols(Elsevier, 2021-10) Cabrera Bañegil, Manuel; Lavado Rodas, Nieves; Muñoz de la Peña, Arsenio; Durán Merás, Isabel; Monago Maraña, OlgaFluorescence spectroscopy in combination with chemometric analysis was applied to discriminate between Japanese Angeleno variety of plums, according to the date of harvesting. Emission spectra (obtained from 280 to 500 nm, and from 345 to 500 nm, respectively) of methanolic extracts of plums at two excitation wavelengths (280 and 330 nm, respectively) were obtained. The fluorescence spectral data were firstly processed by Principal Component Analysis (PCA), as an exploratory study, to extract relevant information from the spectral data, and revealed differentiation between plum samples based in the harvested time. In addition, Partial Least-Squares-Discriminant-Analysis (PLS-DA) was used for the development of the classification models, allowing 100% accuracy to differentiate between the date of harvesting, independently that pulp or skin plum extracts were analyzed. Spectral patterns of plums showed significant differences during maturation period, with a special emphasis between the months of May and September. In addition, calibration models were obtained for different individual polyphenols with partial least-squares (PLS) regression, obtaining the best results for epicatechin and neochlorogenic acid determination.Publicación Analytical technique and chemometrics approaches in authenticating and identifying adulteration of paprika powder using fingerprints: a review.(Elsevier, 2022) Durán Merás, Isabel; Muñoz de la Peña, Arsenio; Galeano Díaz, Teresa; Monago Maraña, OlgaPaprika powder authentication has gained interest in recent decades along with increases in its consumption. There are different Protected Designation of Origins (PDOs) around the world, some of them are from Spain, and it is important to assure the quality parameters that they offer and to provide a guaranty about their quality and authentication. This review covers the latest advances concerning the targeted and untargeted methodologies. These methodologies have been developed to ensure paprika powder authenticity, corroborating that it belongs or not to a certain PDO and that it complies with the regulations and legal standards for its consumption, as well as detection of possible adulterations, mainly with Sudan dyes, which are illegal colorants. Differences between spectroscopic and non-spectroscopic methods have been emphasized. As observed from the literature, paprika powder has not been extensively studied, but the number of papers has been increasing in recent years.Publicación Evaluation of hydrophilic and lipophilic antioxidant capacity in Spanish tomato paste: usefulness of front-face total fluroescence signal combined with PARAFAC(Springer, 2021-12-01) Pardo Botello, Rosario; Chamizo Calero, Fátima; Rodríguez Corchado, Raquel; Torre Carreras, Rosa de la; Galeano Díaz, Teresa; Monago Maraña, OlgaThe hydrophilic and lipophilic antioxidant activities due to the main bioactive components present in Spanish tomato paste samples were studied, using standardized and fluorescent methods. After extraction, phenolic antioxidants (Folin-Ciocalteu method) and total antioxidant activity (TEAC assay) were evaluated, examining differences between hydrophilic and lipophilic extracts corresponding to different samples. Total fluorescence spectra of extracts (excitation-emission matrices, EEMs) were recorded in the front-face mode at two different ranges: 210-300 nm/ 310-390 nm, and 295-350 nm/380-480 nm, for excitation and emission, respectively, in the hydrophilic extracts. In the lipophilic extracts, the first range was 230-283 nm/290-340 nm, while the second range was 315-383 nm/390-500 nm for excitation and emission, respectively. EEMs from a set of 22 samples were analyzed by the second-order multivariate technique Parallel Factor Analysis (PARAFAC). Tentative assignation of the different components to the various fluorophores of tomato was tried, based on literature. Correlation between the antioxidant activity and score values retrieved for different components in PARAFAC model was obtained. The possibility of using EEMs-PARAFAC to evaluate antioxidant activity of hydrophilic and lipophilic compounds in these samples was examined, obtaining good results in accordance with the Folin-Ciocalteu and TEAC assays.Publicación Isocratic LC–DAD–FLD method for the determination of flavonoids in paprika samples by using a rapid resolution column and post-column pH change(Elsevier, 2016-05-15) Galeano Díaz , Teresa; Muñoz de la Peña, Arsenio; Monago Maraña, OlgaThe determination of flavonoid compounds in paprika samples has been performed by liquid chromatography in series diode array and fluorescence detection (LC–DAD–FLD), by means of a pH change to basic medium just before FLD detection. The validation of the method was performed through the establishment of the external standard calibration curves and the analytical figures of merit. Limits of detection ranging from 0.006 to 0.02 mg L−1 and 0.007 to 0.09 mg L−1 were achieved using DAD and FLD detection, respectively. The experimental conditions to carry out the hydrolysis procedure to obtain flavonoid aglycones from flavonoid glycosides have been optimized applying an experimental design and the response surface methodology. The final conditions selected were 2.5 M HCl during 45 min at 85 °C. The repeatability of this procedure was assayed and relative standard deviation (RSD) values for concentration of quercetin and luteolin compounds were lower than 2%. The quantification of quercetin, luteolin and kaempferol compounds was carried out in less than 6 min in paprika samples by means of the external standard calibration. The analytes were extracted with methanol and the extracts were previously subjected to a cleanup procedure to extend the use of the chromatographic column.Publicación Characterization of the metabolic profile of olive tissues (roots, stems and leaves): relationship with cultivars' resistance/susceptibility to the soil fungus Verticillium dahliae.(MDPI, 2023-12-15) Serrano García, Irene; Olmo García, Lucía; Muñoz Cabello de Alba, Iván; León, Lorenzo; Rosa Navarro, Raúl de la; Serrano, Alicia; Gómez Caravaca, Ana María; Carrasco Pancorbo, Alegría; Monago Maraña, OlgaVerticillium wilt of olive (VWO) is one of the most widespread and devastating olive diseases in the world. Harnessing host resistance to the causative agent is considered one of the most important measures within an integrated control strategy of the disease. Aiming to understand the mechanisms underlying olive resistance to VWO, the metabolic profiles of olive leaves, stems and roots from 10 different cultivars with varying levels of susceptibility to this disease were investigated by liquid chromatography coupled to mass spectrometry (LC-MS). The distribution of 56 metabolites among the three olive tissues was quantitatively assessed and the possible relationship between the tissues’ metabolic profiles and resistance to VWO was evaluated by applying unsupervised and supervised multivariate analysis. Principal component analysis (PCA) was used to explore the data, and separate clustering of highly resistant and extremely susceptible cultivars was observed. Moreover, partial least squares discriminant analysis (PLS-DA) models were built to differentiate samples of highly resistant, intermediate susceptible/resistant, and extremely susceptible cultivars. Root models showed the lowest classification capability, but metabolites from leaf and stem were able to satisfactorily discriminate samples according to the level of susceptibility. Some typical compositional patterns of highly resistant and extremely susceptible cultivars were described, and some potential resistance/susceptibility metabolic markers were pointed out.Publicación Quantification of soluble solids and individual sugars in apples by Raman spectroscopy: A feasibility study(Elsevier, 2021-06-08) Afseth, Nils Kristian; Knutsen, Svein Halvor; Wubshet, Sileshi Gizachew; Wold, Jens Petter; Monago Maraña, OlgaThis study reports the feasibility of using Raman spectroscopy for quantification of soluble solids and individual sugars in apples. Six different commercial apple varieties were measured by Raman spectroscopy at three different steps: 1) Intact apples with skin, 2) apples without skin and 3) juices obtained from apples. Results indicated that it is possible to measure Raman signals to a depth of 8 mm into the apple with a wide area Raman probe. Multivariate calibration models were established to evaluate how well Raman spectra can be used to estimate the quality parameters SSC (%), total sugars, glucose, fructose and sucrose. Estimation accuracy for SSC was comparable with what is achievable with near-infrared spectroscopy: Root mean square error of cross-validation (RMSECV) = 0.66, 0.46 and 0.72 % and coefficients of determination (R2) = 0.70, 0.85 and 0.63 for intact apples, apples without skin and juices, respectively. Sucrose and glucose were well estimated with RMSECV of 2.8, 1.9, 2.1 mg/mL for glucose and 5.8, 3.9 and 3.7 mg/mL for sucrose, for the three sample cases, respectively. Coefficient of determination was higher than 0.82 for all models. Regression coefficients for all calibration models highlighted identifiable Raman bands that could be related to the target sugars.Publicación Determination of Quercetin and Luteolin in Paprika Samples by Voltammetry and Partial Least Squares Calibration(Wiley, 2017-09-19) Chamizo González, Francisco; Galeano Díaz, Teresa; Muñoz de la Peña, Arsenio; Monago Maraña, OlgaQuercetin and luteolin are flavonoids with beneficious properties, which are present in paprika. In this work, both have been determined in paprika by using electrochemistry combined with chemometrics. The electrochemical oxidation mechanisms of both analytes have been studied through sampled direct current (DC) voltammetry, differential pulse voltammetry (DPV) and Square Wave Voltammetry (SWV), making use of a glassy carbon electrode. The final technique selected for the quantification was DPV due to its high repeatability with respect SWV. The chemical variables and the instrumental parameters were optimized and the final conditions employed were ethanol: water (20 : 80), 0.75 mol dm−3 of HCl, and a pulse amplitude of 50 mV. Due to the facts that oxidation potential of both analytes were quite similar, their DPV peaks were overlapped, and also because the analytes interaction during the electrochemical process causes a non-additivity of the signals, they could not be quantified separately by direct measurement of peak intensity. For this reason, a chemometric algorithm was applied (partial least squares (PLS) regression in its modality PLS-2). In the case of validation samples, appropriate sets of calibration and validation were built and good results were obtained. This methodology was applied to real paprika samples and the results were similar to those obtained with a HPLC method previously reported.Publicación Monitoring of chlorophylls during the maturation stage of plums by multivariate calibration of RGB data from digital images(MDPI, 2022-12-22) Domínguez Manzano, Jaime; Muñoz de la Peña, Arsenio; Durán Merás, Isabel; Monago Maraña, OlgaThe methodology developed in this study was based on digital imaging processing of plums harvested in eight different weeks during their ripening process. Mean RGB data, histograms, and matrices of RGB data were used to characterise the ripening stage of the plums, in both qualitative and quantitative approaches, by using classification and quantification chemometric methods. An exploratory analysis of data was performed using principal component analysis (PCA) and parallel factor analysis (PARAFAC) in RGB histograms and matrices data, respectively, showing differences in the colour features since the fourth week of harvesting. In the case of the quantitative approach, high correlation was achieved between the histogram data, using partial least squares (PLS), and total chlorophyll content. In addition, between three-way matrixes and total chlorophyll content, good correlations were obtained applying unfolded-PLS (U-PLS) and N-way-PLS (N-PLS). The most accurate results were obtained on the green channel. Analytical parameters obtained were good, with determination coefficients (R2) higher than 0.91 for all models in the first and second-order multivariate analysis. In addition, relative errors of prediction (REPs) were lower than 12% in all models for the green channel. Therefore, the proposed method was a satisfactory alternative to destructive physiological and biochemical methods in the determination of total chlorophylls in plum samples. In the routine analysis, first-order multivariate calibration with PLS analysis is a good option due to the simplicity of data processing.Publicación Chemometric Discrimination Between Smoked and Non-Smoked Paprika Samples. Quantification of PAHs in Smoked Paprika by Fluorescence-U-PLS/RBL(Springer Nature, 2016-10-10) Galeano Díaz, Teresa; Muñoz de la Peña, Arsenio; Monago Maraña, OlgaThis study presents a strategy for differentiating paprika obtained by means of different drying systems. The differentiation is performed using spectroscopic fluorescence in combination with multivariate analysis. The two groups of samples (smoked or non-smoked paprika) are classified according to the content of some of their fluorescent compounds presented in each group, among which several polycyclic aromatic hydrocarbons (PAHs) are included. These compounds are characteristic in smoked food. The full information of excitation–emission matrices (EEMs) is processed with the aid of unsupervised parallel factor analysis (PARAFAC), PARAFAC supervised by linear discriminant analysis (LDA) and discriminant unfolded partial least squares (DU-PLS). The last algorithm allows an adequate classification of unknown paprika samples. Besides, the quantification of several PAHs in paprika was performed by means of unfolded partial least squares with residual bilinearization (U-PLS/RBL). On this way, three (fluorene, phenantrene, and anthracene) out of the five (fluorene, phenantrene, anthracene, pyrene and chrysene) selected analytes were quantified.