Persona: Monago Maraña, Olga
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Monago Maraña
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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.Publicación Four- and five-way excitation-emission luminescence-based data acquisition and modeling for analytical applications. A review(Elsevier, 2019-11-20) Alcaraz, Mirta R.; Goicoechea, Héctor C.; Muñoz de la Peña, Arsenio; Monago Maraña, OlgaThe latest advances in both theory and experimental procedures on third-order/four-way and fourth-order/five-way calibration methods are discussed. This report is focused on excitation–emission (fluorescence and phosphorescence) matrices generation, employing different variables as the third data mode (time retention in chromatography, pH gradient, fluorescence/phosphorescence lifetime, kinetics, or other chemical treatments). Fully capitalizing on the second-order advantage, it has been possible to develop appealing analytical applications in spite of the complexity of the data. Extraction of the significant chemical information about the system under study as well as the individual abundance of the contributing constituents after proper higher-order data decomposition has allowed to analytical researchers performing quantitative analysis of complex samples. The experimental works reported up to the present are introduced and discussed in order to illustrate concepts. Throughout this work, the analytical benefits achieved by modeling third- and fourth-order data are exposed, attempting to contribute to the ongoing debate in the chemometric community regarding the existence and the true nature of the third-order advantage.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 Fluorescence properties of flavonoid compounds. Quantification in paprika samples using spectrofluorimetry coupled to second order chemometric tools(Elsevier, 2016-04-01) Durán Merás, Isabel; Galeano Díaz, Teresa; Muñoz de la Peña, Arsenio; Monago Maraña, OlgaThe influence of pH on the fluorescence of flavonoid compounds was investigated and the highest fluorescence emission was obtained in basic medium. Selected conditions to improve this signal were: pH 9.5, 0.14 M Britton Robinson buffer and methanol between 5% and 10%. The excitation–emission fluorescence matrices of a set of 36 samples of Spanish paprika were analyzed by means of parallel factor analysis (PARAFAC). Thus, the profiles of possible fluorescence components (PARAFAC loadings) were obtained. One of these profiles was identified by matching PARAFAC scores with LC analysis on the same samples. Two clusters of samples were obtained when score values were plotted against each other. Spectrofluorimetry coupled to second order multivariate calibration methods, as unfolded-partial least squares with residual bilinearization (U-PLS/RBL) and multidimensional-partial least-squares with residual bilinearization (N-PLS/RBL), was investigated to quantify quercetin and kaempferol in those samples. Good results were obtained for quercetin by this approach.Publicación Non-destructive Raman spectroscopy as a tool for measuring ASTA color values and Sudan I content in paprika powder(Elsevier, 2019-02-15) Eskildsen, Carl Emil; Afseth, Nils Kristian; Galeano Díaz, Teresa; Muñoz de la Peña, Arsenio; Wold, Jens Petter; Monago Maraña, OlgaThe aim of this study was developing a non-destructive method for the determination of color in paprika powder as well as for detecting possible adulteration with Sudan I. Non-destructive Raman spectroscopy was applied directly to paprika powder employing a laser excitation of 785 nm for the first time. The fluorescence background was estimated, by fitting a polynomial to each spectrum, and then subtracted. After preprocessing the spectra, some peaks were clearly identified as characteristic from pigments present in paprika. The preprocessed Raman spectra were correlated with the ASTA color values of paprika by partial least squares regression (PLSR). Twenty-five paprika samples were adulterated with Sudan I at different levels and the PLSR model was also obtained. The coefficients of determination (R2) were 0.945 and 0.982 for ASTA and Sudan I concentration, respectively, and the root mean square errors of prediction (RMSEP) were 8.8 ASTA values and 0.91 mg/g, respectively. Finally, different approaches were applied to discriminate between adulterated and non-adulterated samples. Best results were obtained for partial least squares – discriminant analysis (PLS-DA), allowing a good discrimination when the adulteration with Sudan I was higher than 0.5%.