1,720,971 research outputs found
RP-HPLC and Chemometrics for wheat flour protein characterization in an industrial bread-making process monitoring context
No full textIn the baking industry, a difficult task is to keep the quality perceived by the consumer as constant as possible, given the inner variability of flour, e.g. due to different wheat mixtures, harvesting time, etc. Here, we evaluated the influence of flour batches properties on bread quality, considering an industrial bread making process. In particular, flour composition in terms of protein fractions (gliadins, glutenins) has been determined by means of RP-HPLC, to assess the inter- and intra-batch variability of flour mixtures deliveries at a baking plant. Multivariate data analysis allowed evaluation of correlation between flour protein composition and technological properties. A great variability within different deliveries of a same flour batch emerged, as well as a considerable seasonal variability. Correlation models among protein sub-fractions, technological properties and bread quality are difficult to establish; however, the role of the protein profile on flour behaviour in bread making could be highlighted
Impiego di HR-NMR per la caratterizzazione di lambruschi DOC dell'Emilia
No full textI vini conosciuti come Lambruschi provengono da un gruppo di vitigni presenti da secoli nel territorio dell' Emilia e profondamente radicati nella tradizione contadina locale. Storicamente, le zone di produzione si trovano nelle province di Modena e Reggio Emilia. La produzione e la commercializzazione di tutti questi vini D.O.C. è regolamentata da specifici disciplinari di produzione. Lo scopo della presente ricerca è stato quello di mettere a punto un metodo per l’analisi e la caratterizzazione di vini Lambruschi DOC dell’Emilia utilizzando la Risonanza Magnetica Nucleare ad alta risoluzione (HR-NMR) mono e bidimensionale. Gli spettri ottenuti dopo ottimizzazione delle sequenze di acquisizione NMR sono stati poi impiegati per la costruzione di modelli chemiometrici mediante tecniche statistiche multivariate, in grado di discriminare tra loro le diverse tipologie di Lambrusco. Questo lavoro va considerato come studio pilota volto allo scopo di valutare l’efficacia della HR-NMR nel fornire informazioni di fingerprint molecolare dei prodotti considerati di qualità tale da poter essere utilizzate a scopo chemiometrico e classificatorio. Per fare tutto ciò si è dovuto innanzitutto individuare, selezionare e ottimizzare le sequenze migliori nell’estrarre informazioni dai campioni queste sequenze sono quindi state sfruttate per affrontare un problema relativamente semplice come la classificazione varietale dei Lambruschi, con l’obiettivo finale di applicarle in un prossimo futuro alla risoluzione di problemi legati all’origine geografica dei prodotti. Tutto questo ha permesso di individuare ed ottimizzare le metodiche analitiche e le sequenze NMR necessarie e di valutare le tecniche chemiometriche più opportune ed efficaci da applicare al tipo di spettri che si ottengono dal vino. I risultati migliori sono stati ottenuti utilizzando 1H-NMR accoppiata con analisi statistiche supervisionate come l’analisi discriminante (GDA). L’approccio seguito ha fornito buoni risultati, sia in termini di qualità del segnale NMR ottenuto che delle tecniche chemiometriche applicate, e permette di affermare che le metodiche approntate sono in grado di estrarre informazioni di qualità dagli spettri registrati tali da essere con ogni probabilità sfruttabili anche per procedere ad una futura costruzione di modelli atti alla discriminazione geografica dei prodotti enologici
DoE optimization of a mercury isotope ratio determination method for environmental studies
No full textBy using the experimental design (DoE) technique, we optimized an analytical method for the determination of mercury isotope ratios by means of cold-vapor multicollector ICP/MS (CV-MC-ICP/MS) to provide absolute Hg isotopic ratio measurements with a suitable internal precision. By running 32 experiments, the influence of mercury and thallium internal standard concentrations, total measuring time and sample flow rate was evaluated. Method was optimized varying Hg concentration between 2 and 20 ng g-1. The model finds out some correlations within the parameters affect the measurements precision and predicts suitable sample measurement precisions for Hg concentrations from 5 ng g-1 Hg upwards.
The method was successfully applied to samples of Manila clams (Ruditapes Philippinarum) coming from the Marano and Grado lagoon (NE Italy), a coastal environment affected by long term mercury contamination mainly due to mining activity. Results show different extents of both mass dependent fractionation (MDF) and mass independent fractionation (MIF) phenomena in clams according to their size and sampling sites in the lagoon. The method is fit for determinations on real samples, allowing for the use of Hg isotopic ratios to study mercury biogeochemical cycles in complex ecosystems
Characterization of lambrusco wines by means of Sr isotope ratio as provenance marker
No full textRecently, geographical origin and authenticity of food are topics of great interest for consumers as well as for producers in the food industry. Furthermore, in the oenological field, these concepts are strictly tied with the quality of food. For different reasons, people are more focused towards food characterized by a well-established geographical origin. In the course of time, the symbiosis of
quality and the geographical origin of products is certainly related to ethics of the producers and the whole determines the reputation of the territory. The present research is part of a project dealing with the development of authenticity and geographical traceability models of Italian wines, with particular reference on Lambrusco wines, which are one of the main typical products of the Modena district. Among the different indicators used for traceability studies, 87Sr, and in particular the 87Sr/86Sr isotopic ratio (I.R.), has provided excellent results for different types of food matrices. Aim of this work is to obtain a reliable fingerprint for Lambrusco
wine on the basis of its 87Sr/86Sr isotopic value, linking it to its territory of provenance. Moreover, different analytical methods for the elimination of matrix interferences, before the Sr/Rb separation on resin, are also tested. In particular, the first method, widely used in literature, consists of the following step: i) ethanol elimination by means of HNO3 addition and ii) sample digestion through microwave assisted in acidic media. While, the second one merely consists in the addition of an aliquot of HNO3. Finally, as a preliminary study, wine samples were pre-treated according to the best procedure and 87Sr/86Sr measurements were accomplished
with an high resolution multicollector inductively coupled plasma mass spectrometry (HR-MC-ICP-MS). The isotopic data of wines were compared with the isotopic range of Modena soils, with the aim to determine a correlation between soil and food, obtaining promising results as far as the potentiality of 87Sr/86Sr as geographical tracer is concerned. To the authors’ knowledge, this is the first report developing an easy analytical methodology for the pretreatment of the studied matrix, obtaining high precision and accuracy measurements, in terms of repeatability, reproducibility and time variability of the monitored indicator
New Silver(I) Coordination Polymer with Fe4 Single-Molecule Magnets as Long Spacer
Full text linkIn continuation of our work on supramolecular architectures of single-molecule magnets (SMMs) as a promising strategy in developing their magnetic performance, in this paper we report the synthesis and single crystal X-ray structure of the centered triangular tetrairon(III) SMM, [Fe4(PhpPy)2(dpm)6], Fe4 (Hdpm = dipivaloylmethane, H3PhpPy = 2-(hydroxymethyl)-
2-(4-(pyridine-4-yl)phenyl)propane-1,3-diol), and its assembly in the coordination polymer {[Fe4(PhpPy)2(dpm)6Ag](ClO4)}n, Fe4Ag, upon reaction with silver(I) perchlorate. Thanks to the presence of the pyridyl rings on the two tripodal ligands, Fe4 behaves as divergent ditopic linker, and due to the Fe4:AgClO4 1:1 ratio, Fe4Ag probably possesses a linear arrangement in which silver(I) ions are linearly coordinated by two nitrogen atoms, forming 1D chains whose positive charge is balanced by the perchlorate anions. The stabilization of such a polymeric structure can be ascribed to the long distance between the two donor nitrogen atoms (23.4 Å) and their donor power. Fe4Ag shows slow relaxation of the magnetization which follows a thermally activated process with Ueff/kB = 11.17(18) K, t0 = 2.24(17) 107 s in zero field, and Ueff/kB = 14.49(5) K, t0 = 3.88(8) 107 s in 1-kOe applied field, in line with what reported for tetrairon(III) SMMs acting as building blocks in polymeric structures
Application of strontium isotopic analysis to the promotion of the Vignola sweet cherry PGI
Full text linkThe perceived quality of a food commodity may critically depend on the food origin, when regional traditions about the same food production are well-known [1]. This is certainly the case of Vignola Sweet Cherry, which is covered by the Protected Geographical Indication (PGI). The development of a territoriality model for Vignola Sweet Cherry PGI by means of analytical indicators hence represent a very intriguing task, useful for the promotion of the product itself.
In the framework of the pilot project “Ciliegia-UNIMORE2014”, we have assessed the effectiveness of the isotope ratio 87Sr/86Sr as direct traceability indicator, since this indicator have already provided excellent results in similar studies. [2].
Thanks to the collaboration of single producers and to the Association of sweet cherry, plum and typical fruit of Vignola, we have monitored the 87Sr/86Sr ratio in soils, branches and sweet cherry fruits of 3 producing fields, as well as in 100 fruit samples belonging to 20 different cultivars and coming from ten municipalities of the region of production. For a more complete characterization of the cherries, the concentration of 10 metals (major and trace constituents) and the polyphenols content have been determined
Study of protein content of wheat flour in relation to technological properties using chromatography, NIRS and chemometrics
No full textMERCURY ISOTOPES DETERMINATIONS IN ENVIRONMENTAL SAMPLES BY MULTICOLLECTOR ICP/MS
No full textMercury isotopes can be an effective tool to investigate about the biogeochemical cycle of Hg, in order to
distinguish among different sources and prevent its well-known pollution in environment and food webs.
In this work, we set up a method for Hg isotopic ratio determination by multicollector ICP-MS
spectrometry by using a cold vapour generator system (CVG). Basically, the system permits to get
measures independent from any matrix effects achieving high precisions and sensitivities. The method
was optimized by Design of Experiment (DoE) technique to minimize inner uncertainty on isotopic
ratios. Instrumental mass bias on measures was accounted by simultaneously monitoring 205Tl/203Tl from
the isotopic SRM NIST 997 and applying the correction algorithm proposed by Yang and Sturgeon.
The method repeatability and reproducibility were evaluated for a two years period on a large data set
built by measuring the NIST 3133 standard solution with an Hg concentration of 20 ng g-1 for more than
500 times. Hg isotope ratios (expressed as mean ± 2 standard deviations), are comparable with those of
others works for all the monitored species, namely 199Hg/198Hg = 1.6881 ± 0.0006, 200Hg/198Hg = 2.3061
± 0.0011, 201Hg/198Hg = 1.3139 ± 0.0014 and 202Hg/198Hg = 2.9635 ± 0.0014.
Precisions and sensitivities of the method are fit for purpose to investigate fractionation phenomena, mass
dependent (MDF) and mass independent (MIF), for Hg that might occur during the uptake processes of
the element and its derivatives in living organisms
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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