Persona: Monago Maraña, Olga
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Publicación Untargeted classification for paprika powder authentication using visible – Near infrared spectroscopy (VIS-NIRS)(Elsevier, 2021-03) Eskildsen, Carl Emil; Galeano Díaz, Teresa; Muñoz de la Peña, Arsenio; Wold, Jens Petter; Monago Maraña, OlgaThis paper describes a non-destructive screening method for authentication of paprika belonging to the Spanish Protected Designation of Origin (PDO) “Pimentón de La Vera”. Different multivariate classification models were developed in order to differentiate PDO and non-PDO samples, using visible-near infrared spectra as fingerprint for each paprika sample. Sample treatment was not required. Principal component analysis (PCA) was applied in different spectral ranges: 400–2500, 400–800 and 800–2500 nm. In all spectral ranges, PCA was largely able to differentiate PDO from non-PDO samples. Partial least-squares - discriminant analysis (PLS-DA), PCA-linear discriminant analysis (LDA) and PCA-quadratic discriminant analysis (QDA) were used as classification methods in the different spectral ranges. All methods were able to differentiate PDO from non-PDO samples, with error rates (ER) lower than 0.15. The best models were those obtained with PLS-DA in the NIR range (800–2500 nm), showing ERs lower than 0.07 and error indexes (IERROR) (false positives) lower than 0.05.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 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 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 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 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 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 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.