Persona: Monago Maraña, Olga
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Monago Maraña
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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 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 Cost-effective fully 3D-printed on-drop electrochemical sensor based on carbon black/polylactic acid: a comparative study with screen-printed sensors in food analysis(Springer, 2024) Monago Maraña, Olga; Aouladtayib-Boulakjar, Nadia; Zapardiel Palenzuela, Antonio; García Domínguez, Amabel; Ayllón Pérez, Jorge; Rodríguez Prieto, Álvaro; Claver Gil, Juan; Camacho López, Ana María; González Crevillén, Agustín3D-printing technology allows scientist to fabricate easily electrochemical sensors. Until now, these sensors were designed employing a large amount of material, which increases the cost and decreases manufacturing throughput. In this work, a low-cost 3D-printed on-drop electrochemical sensor (3D-PES) was fully manufactured by fused filament fabrication, minimizing the number of printing layers. Carbon black/polylactic acid filament was employed, and the design and several printing parameters were optimized to yield the maximum electroanalytical performance using the minimal amount of material. Print speed and extrusion width showed a critical influence on the electroanalytical performance of 3D-PES. Under optimized conditions, the fabrication procedure offered excellent reproducibility (RSD 1.3% in working electrode diameter), speed (< 3 min/unit), and costs (< 0.01 $ in material cost). The 3D-PES was successfully applied to the determination of phloridzin in apple juice. The analytical performance of 3D-PES was compared with an equivalent commercial on-drop screen-printed electrode, yielding similar precision and accuracy but lower sensitivity. However, 3D-PES provides interesting features such as recyclability, biodegradability, low-cost, and the possibility of being manufactured near the point of need, some of which meets several demands of Green Chemistry. This cost-effective printing approach is a green and promising alternative for manufacturing disposable and portable electroanalytical devices, opening new possibilities not only in on-site food analysis but also in point-of-care testing.Publicación Determination of pungency in spicy food by means of excitation-emission fluorescence coupled with second-order chemometric calibration(Elsevier, 2018-04) Guzmán Becerra, María; Muñoz de la Peña, Arsenio; Galeano Díaz, Teresa; Monago Maraña, OlgaCapsaicinoids are a family of compounds responsible for the pungency of spicy foods. In this work, the combination of fluorescence and chemometrics was investigated as a novel quantification method of capsaicinoids in spicy food samples. The excitation–emission matrices (EEMs) of the two major capsaicinoids (capsaicin and dihydrocapsaicin) were identical. Hence, the results were presented as the total content of capsaicinoids. The EEMs of a group of paprika, cayenne and chilli peppers, and of another group of spicy sauces were registered. The decomposition of the EEMs of each group was performed by parallel factor analysis (PARAFAC), obtaining three principal components in each case. After the decomposition, the component corresponding to capsaicinoids was identified by comparison with the profile of a standard mixture of capsaicin and dihydrocapsaicin. In addition, the score values of this component were correlated with the Scoville heat units (SHU) calculated by means of an HPLC–FLD method. Good correlations were obtained in both groups (0.998 and 0.992), confirming the assignation of the component to capsaicinoids. Subsequently, a calibration set was built to carry out the calibration in the spectrofluorimeter, using PARAFAC and U-PLS/RBL as second-order calibration algorithms. Good results for SHU determination were obtained in both groups with both algorithms and when the fluorimetric method was validated by means of liquid chromatographic analysis the relative error of prediction was less than 11.3%.Publicación Acrylamide-fat correlation in californian-style black olives using near-infrared spectroscopy(MDPI, 2023-09-06) Montero Fernández, Ismael; Martín Tornero, Elísabet; Martín Vertedor, Daniel; Fernández Fernández, Antonio; Monago Maraña, OlgaCalifornian-style is one of the most important black table olive elaborations. During its processing, table olives produce acrylamide, a potential carcinogen compound generated during sterilization. In the present study, total fat and acrylamide content in Californian-style table olives were determined and a regression between them was performed (acrylamide concentration range: below limit of detection—2500 ng g−1 and 8–22% for total fat). Nowadays, there are fast and efficient new techniques, such as Near-Infrared Spectroscopy (NIRS) to measure fat content parameters. In that sense, NIRS was used to perform a fat content quantification model in olives in order to indirectly determine acrylamide content. Calibration models for fat quantification were obtained in defatted olive pastes from a unique variety and for olive pastes from different varieties. In the first case, best results were obtained since only one variety was used (R2 = 0.9694; RMSECV = 1.31%; and REP = 8.4%). However, in the second case, results were still acceptable R2 = 0.678, RMSECV = 2.3%, REP = 17.7% and RMSEV = 2.17%. Regression coefficients showed the most influence variables corresponded with fat. The determination coefficient for the fat and acrylamide correlation was high (r = 0.877), being an efficient approach to find out the contribution of fat degradation to acrylamide synthesis in table olives.Publicación Non-destructive fluorescence spectroscopy combined with second-order calibration as a new strategy for the analysis of the illegal Sudan I dye in paprika powder(Elsevier, 2020-05) Eskildsen, Carl Emil; Muñoz de la Peña, Arsenio; Galeano Díaz, Teresa; Wold, Jens Petter; Monago Maraña, OlgaThis paper presents a novel strategy for determination of the illegal dye Sudan I in paprika powder. The method is based on fluorescence spectroscopy combined with second-order calibration, which was employed for the first time for this purpose. The method is non-destructive and requires no sample preparation. It was probed that Sudan I exhibited fluorescence; however, the color of paprika samples affected the signal and it was not possible to quantify this adulterant by means of univariate and first-order calibration. To model the effect of variability of color in samples, a central composite experimental design was performed with varying ASTA (American Spices Trade Association) color values and Sudan I concentrations. Different second-order algorithms were tried for quantification. The best results for calibration and validation were obtained from Unfolded-Partial Least-Squares (U-PLS) and Multi-way Partial Least-Squares (N-PLS). The level of detection ranges were 0.4 – 3 mg/g and 0.5 – 3 mg/g for U-PLS and N-PLS, respectively. This was lower than other methods found in the literature.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 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 Untargeted authentication of fruit juices based on electrochemical fingerprints combined with chemometrics. Adulteration of orange juice as case of study(ELSEVIER, 2024) Monago Maraña, Olga; Zapardiel Palenzuela, Antonio; González Crevillén, AgustínThis work presents a novel strategy for authentication of fruit juices. The methodology is based on an electrochemical method combined with chemometrics. In addition, the case of orange juice adulteration with grapefruit juices was studied using this methodology. The electrochemical fingerprint of different juices showed the influence from different polyphenols according to the type of fruit. First, Principal Component Analysis (PCA) was able to differentiate clusters of different juices, being the higher group distance within apple, orange, and grape juices samples. On the other hand, partial least-squares – discriminant analysis (PLS-DA) and PCA-linear discriminant analysis (LDA) were used as classification methods, obtaining better results for orange and apple models. Furthermore, good results were obtained for the authentication of orange juices, compared to other juices, with an error rate of 0.04 for cross-validation. In the case of adulteration of orange juice was detected using PLS-DA at an adulteration level as low as 1%. Regression vectors for all models highlighted identifiable potential values that could be related to the main polyphenols in each type of fruit. This electrochemical method is rapid, low-cost, and compatible with on-site analysis compared to other laborious analysis described in the literature.Publicación Raman spectroscopy as a tool for characterisation of quality parameters in Norwegian grown apples during ripening(ELSEVIER, 2024) Monago Maraña, Olga; Wold, Jens Petter; Remberg, Siv Fagertun; Sanden, Karen Wahlstrøm; Afseth, Nils KristianThis study shows for the first time the feasibility of Raman spectroscopy as a non-destructive method to follow the ripening process of apple fruits. Two different varieties of apples were studied: ‘Aroma’ and ‘Elstar’. By visual inspection, Raman spectra showed that the starch content was higher in ‘Elstar’ apples compared to ‘Aroma’. The degradation of starch over time could be detected in the Raman spectra, indicating that the method can be used to monitor the ripening process. The ripeness markers starch index, soluble solids content (SSC), and the sugars glucose, fructose and sucrose were determined with traditional destructive methods. Cross validated calibration models based on Raman spectroscopy were obtained for all quality parameters, and test set validation offered good results, with R2 in the range 0.4–0.86 for ‘Aroma’ and 0.4–0.95 for ‘Elstar’, respectively. The regression coefficients showed that the calibrations relied on Raman bands associated with starch and different sugars. The results suggest that Raman spectroscopy in the future could be used to determine the optimal time of harvesting and to sort apples into different degrees of ripeness.
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