1,720,956 research outputs found
Evaluation of wine evolution, application of conventional and innovative approaches
No full textThis book collects the conference proceedings of the 26th Workshop on the Developments in the Italian PhD Research on Food Science Technology and Biotechnology, held at the UniASTISS Polo Universitario Asti Studi Superiori “Rita Levi Montalcini” from 19th to 21st September 2022. The goal of the conference is to gather PhD students from all Italian universities of whom projects deal with food-related topics to define the state of the art of the Italian academic research in this area of study
Approcci innovativi per la valutazione dell'evoluzione di vino bianco imbottigliato e applicazione di tecniche innovative per la gestione dell'ossigeno disciolto
No full textL’evoluzione dei vini bianchi risulta essere una tematica di forte interesse, sia dal punto di vista della ricerca, che produttivo. Tra i parametri cruciali per valutare le potenzialità legate all’evoluzione di un vino bianco, vi sono l’analisi della concentrazione dell’anidride solforosa e la valutazione colore, mediante assorbanza a 420 nm, i quali tuttavia, non restituiscono un quadro esaustivo. Grazie al concomitante avanzamento tecnologico ed all’incremento delle conoscenze in enologia, nuove metodiche permettono oggigiorno di meglio valutare lo stato evolutivo del vino. Tra queste metodiche troviamo la gas-cromatografia per la valutazione della componente volatile e la voltammetria ciclica, quest’ultima risulta essere un’analisi di forte interesse, soprattutto in seguito allo sviluppo di potenziostati portatili e degli elettrodi screen-printed, permettendo un’ulteriore semplificazione della tecnica d’analisi. Data la natura e la complessità della matrice vino, la voltammetria ciclica necessita di conoscenze approfondite per l’interpretazione dei risultati, in quanto dal voltammogramma ottenuto, non risulta possibile differenziare i differenti processi registrati.
Nella presente tesi di dottorato, differenti tipologie di analisi sono state impiegate al fine di valutare l’evoluzione di trentasei vini bianchi monovarietali, prodotti nel nord-est Italia. Sia i parametri classici impiegati per la valutazione dell’evoluzione, quali contenuto di anidride solforosa, assorbanza a 420 nm, sia la valutazione dei composti carbonilici e la voltammetria ciclica sono risultati efficaci e significativi al fine di valutare l’evoluzione dei campioni, seppur quest’ultima in modo minore.
I dati ottenuti dalla voltammetria ciclica, così come gli spettri relativi al campo del UV e del visibile, sono stati impiegati con successo al fine di predire alcune variabili analizzate nel progetto di dottorato, mediante l’applicazione della regressione dei minimi quadrati parziali (PLS).
Inoltre, i dati relativi alla voltammetria ciclica sono stati correlati alle distanze sul piano fattoriale basato sull’analisi delle componenti principali (PCA) di diversi parametri al fine di valutarne la
relazione. Tale elaborazione sarà utile per lo sviluppo futuro di un modello previsionale in grado di stimare i cambiamenti legati all'evoluzione.
Contestualmente, è stato sviluppato un ulteriore progetto al fine di determinare gli effetti sull’evoluzione del vino legati sia alla modulazione dei gas disciolti, mediante applicazione della membrana contactor, sia dall'uso di diverse tipologie di chiusure. Nel dettaglio, sono state testate tre diverse chiusure a vite, ciascuna con caratteristiche differenti, insieme a un tappo in sughero agglomerato.
I risultati ottenuti hanno evidenziato che la gestione dei gas disciolti durante la fase di imbottigliamento ha comportato una significativa riduzione della concentrazione di ossigeno disciolto, soprattutto in combinazione con l'utilizzo di chiusure a vite.
L'utilizzo della membrana contactor ha inoltre dimostrato di avere un impatto positivo sull’evoluzione. In particolare, l'analisi dei parametri chimici ha rivelato una minore propensione all'evoluzione in combinazione con tappo in sughero agglomerato e nel liner Saranex. Per quanto riguarda la presenza dei composti carbonilici, i liner 'M' e Saranex hanno mostrato una minore concentrazione rispetto alle altre chiusure impiegate, suggerendo una minore evoluzione nel tempo.
Quindi, l'utilizzo della membrana contattore si conferma efficace nel preservare il vino bianco imbottigliato sia nel breve che nel lungo periodo.Evolution in white wines is a topic of considerable interest from both research and production perspectives. Analytically, the concentration of sulfur dioxide and color evaluation, measured by absorbance at 420 nm, are crucial parameters for assessing the potential evolution of a sample. However, these parameters do not provide an exhaustive vision and, in this regard, technological progress and increased knowledge in enology have allowed the development of methodologies to obtain more detailed parameters to assess the evolution state of a wine, such as the use of gas chromatography to evaluate the volatile component. Cyclic voltammetry is an interesting analysis, especially after the development of portable potentiostats and disposable screen-printed electrodes, which have allowed a further simplification of this method of analysis. However, interpreting the results of cyclic voltammetry requires a detailed understanding of the analysis and the matrix. Due to the complexity of the wine matrix, the resulting voltammogram may not allow the discrimination of the different processes.
In this work, different typologies of analysis have been used to evaluate the evolution of thirty-six monovarietal white wines, produced in the north-east of Italy. The parameters commonly used to evaluate the evolution of the samples, such as sulfur dioxide content and absorbance at 420 nm, were found to be effective, as well as, the evaluation of carbonyl compounds. Furthermore, cyclic voltammetry was found to be effective, for this purpose, but in a lower order.
Additionally, data acquired from cyclic voltammetry, as well as spectra obtained in the UV and visible spectra, were used to predict some variables analyzed in the dissertation, with good results, through the application of Partial Least Squares (PLS).
Moreover, data related to cyclic voltammetry were correlated to distances on a factorial plane based on PCA of different parameters to assess the relationship. This will be useful for the future development of a forecast model that can estimate evolution-related changes.
Finally, a second project was developed to evaluate the effect of managing dissolved gases, specifically oxygen, using a contactor membrane. The project also examined the effect of different
closures, including an agglomerated cork closure and three different screw caps with different liners and different characteristics, the most important of which, from an enological point of view, is the oxygen transfer rate (OTR).
Gas management during bottling resulted in a significant decrease in dissolved oxygen concentration, particularly when combined with screw caps.
The use of the contactor membrane resulted in a lower tendency of evolution, as determined by chemical parameters and the assessment of the carbonyl compounds contained in the wine. The analysis reveals a tendency towards lower evolution of agglomerated cork closures and the use of Saranex liner by the assesment of chemical parameters, while with regard to the presence of carbonyl compounds, some of the tested liners differed from the rest by a lower presence, thus a lower evolution. Therefore, the use of contactor membrane is an effective method for preserving bottled white wine in the short- and long-term
Effetto della permeabilità della chiusura e di diverse variabili ambientali sull'evoluzione di vini bianchi in bottiglia
No full text
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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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