1,720,964 research outputs found
Organosulfur volatile profiles in Italian red garlic (Allium Sativum L.) varieties investigated by HS-SPME/GC-MS and chemometrics
No full textSixty-eight samples of red garlic harvested in four Italian areas were analyzed by means of head-space solid phase micro-extraction (HS-SPME) coupled to gas-chromatography with mass spectrometry (GC-MS) to test whether the volatile composition is related with the geographical origin of the bulbs. HS-SPME/GC-MS analysis was optimized by means of a Box-Behnken design of experiment. Once GC-MS signals were collected and the volatiles identified, geographical classification was attempted by Partial Least Squares Discriminant Analysis (PLS-DA). To perform the external validation of the model, the investigated samples were divided into a training and a test set of 42 and 26 samples, respectively. The PLS-DA model correctly classified 21 external samples. Eventually, Variable Importance in Projection (VIP) analysis identified 13 organosulfur compounds (two sulphides, eight disulphides and three trisulphides), among the 25 detected ones, displaying a content in garlic flavour significantly dependent on the geographical origin of the bulbs
VALUTAZIONE DEI LIVELLI DI CONTAMINAZIONE DA MICOTOSSINE EMERGENTI NEGLI ALIMENTI PER L’INFANZIA
No full textScopo del lavoro è la determinazione dei livelli di contaminazione da micotossine
emergenti (beauvericina ed enniatine A, A1, B, B1) in campioni di alimenti per l’infanzia a
base di cereali. Si tratta di metaboliti secondari prodotti da specie fungine appartenenti al
genere Fusarium, la cui tossicità è correlata alla capacità di formare complessi stabili con
cationi metallici mono e divalenti che provocano effetti citotossici. Il metodo messo a punto
per la determinazione della beauvericina e delle enniatine prevede una fase di estrazione con
acetonitrile e successiva purificazione per eliminare gli interferenti e concentrare gli analiti.
La separazione cromatografica è stata effettuata in cromatografia liquida, mentre per la
rilevazione strumentale è stata utilizzata la spettrometria di massa, considerata tecnica di
elezione per le analisi di conferma nell’ambito dei controlli ufficiali degli alimenti. Nello
studio di validazione sono stati definiti i seguenti criteri stabiliti dal Regolamento (UE)
2017/625: specificità, linearità, limite di quantificazione, ripetibilità, riproducibilità,
accuratezza ed incertezza di misura. Il metodo è risultato applicabile in un range di
concentrazione compreso tra limite di quantificazione (0,30 μg/kg per beauvericina ed
enniatina A, 0,60 μg/kg per le altre micotossine) e 20 μg/kg. I recuperi ottenuti erano
compresi tra 79,2% e 103,9% con un valore massimo di deviazione standard di riproducibilità
pari a 17,4%. I risultati delle analisi hanno evidenziato che la beauvericina è stata rilevata in
tutte le tipologie di alimenti, con un’incidenza del 19,3% nelle pastine a una concentrazione
media di 0,62 μg/kg. Per quanto riguarda le creme e i biscotti la beauvericina è stata
riscontrata nel 10% dei campioni a concentrazioni medie rispettivamente di 0,39 e 0,36
μg/kg. Tra le enniatine, è stata osservata una maggiore incidenza dell’enniatina B nei biscotti
(90%), creme (28,6%) e pastine (7,7%), a concentrazioni medie di 4,1, 1,3 e 0,77 μg/kg.
L’enniatina A non è stata riscontrata in nessuno dei campioni analizzati, mentre l’enniatina
A1 è stata ritrovata solo in un campione di creme con valori pari a 1,1 μg/kg. I risultati di
questo studio hanno fatto emergere la necessità sia di stabilire dei limiti massimi anche per
queste micotossine nell’ambito del Regolamento (UE) 2023/915 sui contaminanti, che quella
di predisporre e implementare opportuni piani di monitoraggio, con una particolare
attenzione agli alimenti per l’infanzia
Official controls for the determination of lipophilic marine biotoxins in mussels farmed along the Adriatic coast of Central Italy
No full textIn the present study, 334 samples of mussels (Mytilus galloprovincialis) harvested along the coasts of the Central Adriatic Sea during the years 2020–2021 were analyzed for the presence of lipophilic marine biotoxins according to the European Harmonized Standard Operating Procedure. The results showed that 74 (22%) and 84 (25%) samples were positive to okadaic acid and yessotoxin groups, respectively. Among them, only 11 (3.3%) samples resulted as non-compliant, as they exceeded the maximum limits (160 μg okadaic acid equivalent/kg) established by the Regulation
(EC) 853/2004. The method applied in this study was able to detect and quantify lipophilic marine biotoxins concentrations, in order to monitor their presence in molluscs and avoid the risk of consumer exposure
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
Assessment of dietary exposure to ochratoxin A related to its concentrations in different foods
No full textVariations 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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