1,720,957 research outputs found
Carrageenan as possible stabilizer of calcium tartrate in wine
No full textCalcium-induced instability has recently become a major issue in bottled wines, as an effect of compositional changes induced by global warming. Up to date, few tools are available for calcium stabilization purposes. The present research was aimed at evaluating the potential activity of carrageenans (mixture of ι- and κ-) as stabilizers of calcium tartrate (CaT) in white and rosé wines. Four white and two rosé wines, with differing CaT and potassium bitartrate (KHT) stability were characterized. The addition of carrageenans improved both CaT and KHT stability, determining a decrease of saturation temperatures of both CaT and KHT (TsatCaT and TsatKHT). Sodium bentonite was used to evaluate possible synergic effect. The addition of carrageenans (0.75 g L−1) followed by sodium bentonite (0.5 g L−1) allowed to stabilize CaT in all wines, with a TsatCa2+ mean value of 6.7 °C; all samples also reached protein stability, with the exception of one sample that slightly exceeded the conventional threshold of protein stability. As a plus, KHT stability was also improved. The mini-contact test with seeds of micronized CaT, DLS analysis and FTIR spectra confirmed that CaT stability was due to Ca2+ ions colloidal stabilization rather than removal; that the mechanism of stabilization could include ternary complexes involving carrageenan, calcium ions and proteins; and that the synergic effect of bentonite could be attributed to competitive adsorption of proteins, with consequent adsorption of larger amounts of Ca2+ ions by carrageenan
Ageing of Red Wine (cv. Negroamaro) in Mediterranean Areas: Impact of Different Barrels and Apulian Traditional Amphorae on Phenolic Indices, Volatile Composition and Sensory Analysis
Get PDFThis study investigated the impact of different ageing containers on the volatile composition and quality of Negroamaro wine, a key variety from Apulia, Italy. Seven vessel types were evaluated: traditional Apulian amphorae (ozza), five types of oak barrels (American oak, French oak, European oak, a French + European oak and a multi-wood mix) and glass bottles as the control. The impact of the vessels was evaluated after 6 months of ageing through the characterization of phenolic, volatile and sensory profiles. Amphorae allowed a specific evolution of the wine’s primary aromas, such as fruity and floral notes, while enhancing volatile compounds like furaneol, which contributed to caramel and red fruit nuances, and also 3-methyl-2,4-nonanedione, a key compound related to anise, plum and premature ageing, depending on its concentration. This container also demonstrated effectiveness in stabilizing anthocyanin–tannin complexes, supporting color stabilization. Oak barrels allowed different outcomes to be obtained in terms of color stabilization, volatile profile, aroma and astringency. French oak exhibited the highest phenolic and tannin levels, enhancing anthocyanin stabilization and color intensity. European oak followed closely, while American oak excelled in color stabilization, with tannins less reactive to polymers. Mixed wood barrels showed lower phenolic extraction and the best astringency evolution
Influence of prolonged maceration on phenolic compounds, volatile profile and sensory properties of wines from Minutolo and Verdeca, two Apulian white grape varieties
Get PDFProlonged maceration was applied to two Apulian white grape cultivars, Minutolo and Verdeca. The impact of prolonged maceration (up to six months) on the quality of the wines was evaluated through characterization of phenolic, volatile and sensory profiles. Macerated wines presented a peak of extraction after 4 months, followed by a decrease probably due to precipitation/reabsorption. Extraction of seed phenols occurred during longer maceration times. Volatile profile was also modified, showing a different behavior at different maceration times. Oxidation and aging compounds appeared during maceration, that are unusual for traditional white wines. Furthermore, maceration successfully enhanced varietal identity of Minutolo. The terpene profile of Minutolo wines changed during maceration, with a maximum of terpenols after 1 month of maceration, while longer maceration added a pattern of oxidized terpenes. Sensory analysis highlighted clearly distinct profiles of wines, according to both cultivar and maceration time. A good attitude was observed of both varieties to undergo maceration. In particular, Verdeca appeared suitable for longer maceration times, with flowery, citrus and apricot notes after 4 months, while enhanced apricot notes were perceived after 6 months. On the other hand, Minutolo wine after 6 months of maceration was characterized by a marked astringency and peach flavor
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
Low-pressure continuous dynamic extraction from oak chips combined with passive micro-oxygenation to tune red wine properties
Get PDFStatic infusion of oak chips in wine is a common practice during wine ageing, aimed at improving sensory properties and stability of wines. The wine/chips contact required to reach the desired effect can last several weeks or months. A low-pressure continuous dynamic (LPCD) extractor in which a closed-circle, low-pressure continuous flow of wine passes through an extraction cell filled with chips, was evaluated as a tool to tune red wine properties in few hours. The aim of this work was to evaluate the effect of the use of a LPCD extractor the effect on color, volatile compounds and sensory properties of a Primitivo wine, as well as to assess the combined effect of LPCD extractor, passive microxygenation through polyethylenetereftalate (PET) containers and exogenous tannins. Their combined effect caused a significant increase of stabilized pigments was observed, without compromising the aroma profile. LPCD extraction, passive micro-oxygenation through plastic materials and enological tannins can be considered as a low-cost, and potentially low-impact, integrated technological platform suitable to tune wine sensory properties and stability, when either traditional approaches (such as barrel aging) or other assisted extraction technologies are not applicable or preferred, even in small wineries
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