6 research outputs found
Identification of metabolic content of selected Amarone wine
No full textThe metabolic characterisation of food and beverages nowadays has been largely employed in combination with multivariate data analysis. In this work, the valuable Amarone "Passito" dry red wine produced in Verona area (Italy) was investigated in order to find a possible correlation between metabolic content and vintage/ageing process. A total number of 46 wine samples from 11 different winemakers, three different vintages and ageing process were investigated without sample preparation. 1H NMR spectra were analysed in combination with principal component analysis (PCA) and partial least square discriminant analysis (PLS-DA) protocols to investigate vintage and ageing effects on samples differentiation based on the metabolic content. The results indicated amino acids, sugars, and aromatic compounds the most relevant discriminant variables for Amarone wine sample
NMR investigations for a quality assessment of Italian PDO saffron (<i>Crocus sativus</i> L.)
No full textHigh-resolution NMR spectroscopy was employed to analyze Italian Protected Designation of Origin (PDO) saffron from L'Aquila, S. Gimignano and Sardinia and commercial saffron samples available on the Italian market. An extensive resonance assignment of DMSO saffron extract was reported, including glucose and gentiobiose in bound and unbound form for the first time. A multivariate statistical analysis of NMR data led to a clustering of samples by performing unsupervised PCA. OPLS-DA model was successively performed to highlight the markers responsible for this discrimination. An analysis of the corresponding S-plot indicated that picrocrocin and crocins were the most relevant compounds for characterizing Italian PDO saffron. By contrast, commercial saffron barely contained these characteristic compounds, and they were primarily enriched in fatty acids
High throughput soft embossing process for micro-patterning of PEDOT thin films
No full textThe patterning of conductive polymers is a major challenge in the implementation of these materials in several research and industrial applications, spanning from photovoltaics to biosensors. Within this context, we have developed a reliable technique to pattern a thin layer of the conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) by means of a low cost and high throughput soft embossing process. We were able to reproduce a functional conductive pattern with a minimum dimension of 1 μm and to fabricate electrically decoupled electrodes. Moreover, the conductivity of the PEDOT films has been characterized, finding that a post-processing treatment with Ethylene Glycol allows an increase in conductivity and a decrease in water solubility of the PEDOT film. Finally, cyclic voltammetry demonstrates that the post-treatment also ensures the electrochemical activity of the film. Our technology offers a facile solution for the patterning of organic conductors with resolution in the micro scale, and can be the basis for the realization and development of polymeric microdevices with electrical and electrochemical functionalities
Performance assessment in fingerprinting and multi component quantitative NMR analyses
No full textAn inter-laboratory comparison (ILC) was organized with the aim to set up quality control indicators suitable for
multi component quantitative analysis by nuclear magnetic resonance (NMR) spectroscopy. 36 NMR data sets (corresponding to
1260 NMR spectra) were produced by 30 participants using 34 NMR spectrometers. The calibration line method was chosen for the
quantification of a five-component model mixture. Results show that quantitative NMR is a robust quantification tool and that 26
out of 36 data sets resulted in statistically equivalent calibration lines for all considered NMR signals. The performance of each laboratory
was assessed by means of a new performance index (named Qp-score) which is related to the difference between the experimental
and the consensus values of the slope of the calibration lines. Laboratories endowed with Qp-score falling within the suitable
acceptability range are qualified to produce NMR spectra that can be considered statistically equivalent in terms of relative intensities
of the signals. In addition, the specific response of nuclei to the experimental excitation/relaxation conditions was addressed
by means of the parameter named NR. NR is related to the difference between the theoretical and the consensus slopes of
the calibration lines and is specific for each signal produced by a well-defined set of acquisition parameter
NMR applications in food analysis. Part B
No full textApplications of low-field NMR relaxometry and NMR-imaging in the analysis of food samples are described using examples of different food matrices and different problems related to food processing, maturation and ageing, authenticity, shelf-life, perishability etc
Development of a model for identification of adulterants for quality control of garlic powder
No full textgráficas, ilustraciones, tablasEl fraude alimentario constituye una problemática global que no sólo afecta la economía sino también la salud y confianza del consumidor. El ajo en polvo es una especia susceptible a la adulteración con sustancias de bajo costo y apariencia similar: tiza blanca y almidón de maíz. Dado que los métodos existentes para identificar adulterantes en especias requieren equipos sofisticados y un elevado consumo de tiempo, es necesario recurrir a técnicas alternativas. El objetivo de esta investigación fue desarrollar modelos de predicción basados en espectroscopía en infrarrojo cercano, que identifiquen la presencia de tiza blanca o almidón de maíz en ajo en polvo y que cuantifiquen estos compuestos en las muestras adulteradas. Para este fin, se prepararon 626 muestras de dicha especia adulteradas en concentraciones entre 0 y 30% (w/w), se distribuyeron 500 muestras para calibración y 126 muestras para validación. Luego, se desarrollaron los modelos de clasificación por regresión de mínimos cuadrados parciales (PLS) con análisis discriminante y los modelos de cuantificación por PLS, con validación cruzada y externa, utilizando tratamientos de Variable Normal Estándar, Correlación de Dispersión Multiplicativa y las derivadas de Savitzky-Golay. El modelo de clasificación permitió identificar las muestras adulteradas y el tipo de adulterante, en tanto los modelos de cuantificación de cada adulterante permitieron conocer el porcentaje de adulteración en las muestras de ajo en polvo, con valores del error cuadrático medio de predicción (RMSEP) entre 0.6490% - 1.576%. Los resultados indicaron que es posible utilizar modelos espectrales para determinar la autenticación del ajo en polvo. (Texto tomado de la fuente)Food fraud is a global problem that not only affects the economy but also consumer health and confidence. Garlic powder is a spice that is susceptible to adulteration with low-cost substances of similar appearance: white chalk and corn starch. Since existing methods to identify adulterants in spices require high-tech and time-consuming equipment, alternative techniques are required. The objective of this research was to develop predictive models based on near infrared spectroscopy to identify the presence of white chalk or corn starch in garlic powder and quantify these compounds in adulterated samples. For this purpose, 626 samples of this spice adulterated in concentrations between 0 and 30% (w/w) were used, 500 samples were distributed for calibration and 126 samples for validation. Then, classification models were developed by partial least squares (PLS) regression with discriminant analysis and quantification models by PLS, with cross-validation and external validation, using Standard Normal Variable, Multiplicative Dispersion Correlation and Savitzky-Golay derivatives treatments. The classification model allowed the identification of adulterated samples and the type of adulterant, while the quantification models for each adulterant allowed knowing the percentage of adulteration in garlic powder samples, with root mean square error of prediction (RMSEP) values between 0.6490% - 1.576%. The results indicated that it is possible to use spectral models to determine the authentication of garlic powder. (Tex taken from the source)La financiación se obtuvo a través de la Convocatoria de Apoyo a Semilleros de Investigación de la Facultad de Ingeniería 2019 y la Convocatoria para el apoyo a Proyectos de Investigación y Creación artística de la Sede Bogotá de la Universidad Nacional de Colombia - 2019.Un resumen del Capitulo 2 fue publicado en la revista estudiantil de divulgación y cultura agrícola INNAGRI, ISSN en línea 2806-0490: http://bienestar.bogota.unal.edu.co/pgp/Publicaciones/innagri/innagri.htmlMaestríaMagíster en Ciencia y Tecnología de AlimentosMetología utilizada en quimiometría para el análisis espectral y contrucción de modelos de predicción.Calidad de aimento
