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Suscettibilità alla fotossidazione del formaggio DOP Asiago d’allevo vecchio. Risultati preliminari
No full textGli alimenti sono potenzialmente esposti all’azione degradativa della luce durante tutta la loro vita commerciale. I fenomeni foto-ossidativi causano lo scadimento organolettico del prodotto, la perdita del valore nutrizionale e lo sviluppo di composti potenzialmente nocivi per la salute del consumatore. La presenza del packaging limita solo parzialmente tale fenomeno.
Si è valutata la suscettibilità alla fotossidazione del formaggio Asiago d’allevo D.O.P. porzionato in preincarto mantenuto in condizioni di conservazione commerciale. La valutazione ha preso in considerazione l’effetto dell’origine (formaggio di montagna vs. formaggio di pianura), dell’esposizione (buio vs. luce) e del tempo di conservazione (0÷336 ore) nei confronti del colore (misurato strumentalmente), contenuto di riboflavina e formazione di composti secondari dell’ossidazione lipidica. Il formaggio di montagna presentava un maggior valore dell’indice del giallo (P<0,001) e del rosso (P<0,001) mentre il contenuto dei riboflavina era significativamente maggiore in quello di pianura (P<0,001) che presentava anche una minore ossidazione dei lipidi (P<0,01). Luce e tempo di conservazione hanno comportato la progressiva riduzione dell’indice del giallo (P<0,001 per entrambi gli effetti) e del rosso (P<0,001 per entrambi gli effetti) e la riduzione del contenuto di riboflavina (P<0,01 e P<0,001 rispettivamente). Lo sviluppo dei prodotti secondari dell’ossidazione, invece, non sembra essere condizionato dall’esposizione alla radiazione luminosa ma dalla presenza di ossigeno all’interno della confezione (P<0,001). Il prodotto di montagna sembra essere maggiormente suscettibile.
Ulteriori analisi dovranno essere condotte per valutare l’effetto della radiazione luminosa e della presenza di ossigeno a carico delle vitamine liposolubili
Storage test su succo di mela trattato con ultrasuoni
No full textIl succo rappresenta il principale prodotto della trasformazione delle mele. È apprezzato e consumato da persone di tutte le età per le sue qualità organolettiche e nutrizionali. Attualmente la pastorizzazione è il metodo convenzionale utilizzato per la conservazione dei succhi di frutta, ma è responsabile di alterazioni del sapore e delle qualità nutrizionali. I consumatori preferiscono succhi dal gusto fresco e che presentino una perdita minima dell’aroma tipico. Per soddisfare queste esigenze negli ultimi anni sono stati studiati diversi metodi alternativi al trattamento termico. Tra le nuove tecnologie la sonicazione, da sola o in combinazione con un blando trattamento termico, si è mostrata efficace nei confronti di diversi batteri. Scopo del presente lavoro è stato quello di valutare l'efficacia dell'uso degli ultrasuoni quale trattamento alternativo all'applicazione del calore nel tentativo di mantenere le caratteristiche organolettiche tipiche di un succo di mela "naturale". In particolare è stata valutata l'azione sulla microflora residente e la shelf-life del prodotto attraverso l'analisi microbiologica e sensoriale. Il succo trattato con ultrasuoni ha evidenziato una riduzione della conta microbica totale mesofila e psicrofila rispettivamente di circa 3 log ufc/ml e 5 log ufc/ml e un notevole sviluppo dei lieviti. La valutazione generale espressa dai giudici, attraverso un test sensoriale, è stato a favore del succo sonicato, seguono il succo trattato termicamente e il controllo. In generale, l’utilizzo degli ultrasuoni sembra essere una buona alternativa alla pastorizzazione per la produzione di un succo di mela di buona qualità
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
Use of near infrared spectroscopy and chemometrics to evaluate the shelf-life of cloudy sonicated apple juice
No full textFresh products, such as cloudy apple juice, could be preserved from early spoilage through the application of non-thermal
processes such as sonication. However, shelf-life analyses based on microbiological and sensory evaluations are expensive
and time consuming. Few studies have applied near infrared spectroscopy to evaluate the quality and decay of apple juices.
Here, a feasibility trial was conducted to study the spectral behaviour at 1300–2500 nm combined with chemometric
approaches. The shelf-life was monitored during two experiments, a challenge test with juices inoculated with spoilage
yeasts (inoculated non-sonicated (INS)) and then submitted to sonication treatments (inoculated sonicated (IS)), and a
storage test to evaluate the spoilage on non-inoculated juices (non-inoculated non-sonicated (NINS)) and sonicated noninoculated
juices (non-inoculated sonicated (NIS)). These experiments were investigated at six different refrigeration times
7, 14, 21, 28 and 60 days. Two functions were modelled to describe the behaviours of the first principal component according
to the storage time. In agreement with a previous chemical and sensory evaluation, this approach allowed us to highlight
shelf-life end points of 7 and 14 days for non-sonicated and sonicated samples, respectively. Three different models were
evaluated for classification purposes: (1) sonicated versus non-treated samples, (2) end-point shelf-life evaluation at seven
days for the NINS and INS juices and (3) end-point shelf-life discrimination at 14 days for IS and NIS samples. A partial least
square-discriminant analysis enabled a group classification with accuracy values ranging from 0.63 to 1.00. The application
of a variable importance in projection index to interpret the wavelengths of the spectral features suggests a contribution of
organic acids and lipids to the prediction of decay. A canonical discriminant analysis provided a clearer separation of
samples according to the storage time, especially in relation to the two time thresholds of 7 and 14 days
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
Minimum bactericidal concentration of phenols extracted from oil vegetation water on spoilers, starters and food-borne bacteria
Full text linkThe aim of the study was to assess the in vitro effect of phenols extracted from oil vegetation water (PEOW) on several food-borne strains. Antibacterial activity of PEOW was based on the minimum bactericidal concentration (MBC) on microtitre assay. The taxa tested were: Staphylococcus (n. 5), Listeria (n. 4), Escherichia (n. 2), Salmonella (n. 1), Pseudomonas (n. 3), Lactobacillus (n. 2) and Pediococcus (n. 1). S. aureus and L. monocytogens showed the lowest level of resistance to PEOW (MBC=1.5-3 mg/mL). In contrast, the Gram negative strains (e.g. S. Typhimurium and Pseudomonas spp.) were in some cases unaffected by the tested doses and the MBCs ranged between 6 to 12 mg/mL. Starter cultures were dramatically reduced on growth (e.g. Staphylococcus xylosus; 0.75 mg/mL MBC). The thresholds for pathogenic strains could be considered for further applications of PEOW in food models (e.g. shelf life or challenge test studies)
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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