1,720,977 research outputs found
Volatile compounds in Amarone wines: occurrence, variability, and relationship with grape composition and vinification variables
Get PDFAmarone della Valpolicella is one of the most important wines in the north of Italy, representing an important asset and a source of income and reputation for the region. Amarone is a rather unique example of dry red wine, as it is elaborated from withered grapes of varieties only grown locally, with its production regulation also imposing a minimum aging in oak of two years. These conditions result in specific wine aroma and flavor character. Most of the studies done on Amarone focused on aspects related to withering and therefore on grapes, especially Corvina, leaving a gap concerning the compositional characteristics of Amarone wine, as well as how the main key aspects of Amarone production influence its composition. The main objective of this thesis was to provide a comprehensive overview of the aroma composition of Amarone and to investigate the influence of the main technological processes applied in its production on key volatile compounds. To achieve this, the following methodology was implemented: first, the chemical and sensory characterization of commercial Amarone wines from vintage 2015 and 2016 was performed, including quantification of volatile compounds of different chemical classes and, in some cases, sensory assessment of their likely contribution to perceived Amarone odor. Second, the key technological steps of Amarone production, namely withering, fermentation, and aging were studied through a series of experiments to determine their impact on the formation of relevant aroma compounds in grapes and wines. For the first part, results showed that Amarone commercial wines were characterized by high odor impact of compounds such as of ethyl acetate, fruity esters, and β-damascenone. In addition, the existence of different ‘chemical styles’ within Amarone was highlighted, with some wines being characterized by high odor impact for compounds such as cineoles, ethyl phenols, DMS, and oak-related compounds. Some of these differences in chemical composition showed a good correspondence with the sensory data. The second part of the work was mainly focused on understanding the factors associated with the most relevant aroma compounds identified in the first part, with the aim of understanding the most influencing production variables. Withering was an important factor affecting key volatile compounds in both grapes and wines. Withering influenced positively the grape content of certain glycosidic precursors as well as of the terpene compound terpinen-4-ol, which appeared to be a key precursor to 1,4-cineole formation during aging. To this point, aging was a major factor in the development of key compounds such as DMS, cineoles, TDN, and TPB whose occurrence was mostly due to precursors presence. Finally, aspects related to fermentation also influenced the occurrence of these compounds. In the case of ethyl esters and ethyl acetate, grape composition, in particular YAN content, and yeast of choice influenced greatly. The present work provided an extensive characterization of Amarone wines and grapes, highlighting the key molecules that characterize their composition. In addition, in consideration of the complexity of Amarone wines, this thesis aimed to provide a framework to study the different technological steps which affect the formation of aroma compounds
Dimethyl Sulfide (DMS) in Amarone Wines: Influence of Aging, Withering, Grape Variety, and Geographical Origin
Get PDFOccurrence of dimethyl sulfide (DMS), a potent aroma compound accumulating during aging, was investigated in commercial and experimental Amarone wines. In commercial Amarone, DMS was observed in concentrations ranging from 2.9 to 64.3 mu g/L. Model aging studies on experimental wines indicated that DMS in Amarone is strongly associated with aging and that wines from different vineyards can vary significantly in their ability to accumulate DMS during aging. The capacity of certain vineyards to give wines with higher DMS-forming potential was consistent across three consecutive vintages, representing a true terroir factor to be expressed with aging. Wine content of primary amino acids (PAN), a commonly analyzed enological parameter of grape must, was shown to be positively correlated with DMS accumulation during aging. Grape withering also increased DMS-forming potential mostly due to increased PAN resulting from concentration due to water loss. Increased pH due to withering also contributed to a higher DMS content of withered wines, but to a lower extent. In certain vineyard sites, an influence of vintage conditions on DMS-forming potential was also observed
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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