1,721,067 research outputs found
Desarrollo de cultivos micróbicos protectivos para la industria alimentaria
Full text linkSe estudió la actividad antagonista de 52 cepas de Lactobacillus plantarum previamente aisladas de
diferentes matrices alimentarias. Se evaluó la actividad antimicróbica en diferentes condiciones de
crecimiento sobre microorganismos indeseados como Listeria monocytogenes, Clostridium
botulinum, como también sobre microorganismos alterantes como Clostridium butyricum e
Pseudomonas spp. Los resultados obtenidos han evidenciado que entre las cepas aisladas algunas de
éstas son capaces de expresar actividad antagonista de interés particular para la industria alimentaria.
En lo específico, las cepas aisladas de ambientes caracterizados por condiciones ecológicas hostiles
(pH, aw, etc.) muestran una mayor actividad antagonista. Esto último, en base a los resultados
obtenidos, puede ser debido a la capacidad de las cepas en estudio de producir sustancias
antimicróbicas atribuible al ácido fenil-láctico y al ácido fenil-acético. Además, se ha evidenciado
que la acción antimicrobiana de las cepas varia en función del pH y de la fase de crecimiento,
específicamente al final de la fase exponencial y en correspondencia a niveles de pH inferiores a 5.
Por lo tanto, los conocimientos adquiridos a través del presente trabajo ofrecen información sobre
aquellos que podrían ser los ambientes alimentarios que, según sus características, podrían ser
compatibles con el uso de las cepas objeto de estudio.Italia. Università degli Studi del Molise. Beca Unimo
Relationship between the type of production and the microbiological and chemical features of ventricina
No full textLa ventricina, prodotta nell’area a confine tra Abruzzo e Molise, è un insaccato stagionato preparato con carne suina, abbondantemente speziata con peperone dolce e peperoncino piccante. La presente tesi di dottorato ha rivolto l’attenzione allo studio degli aspetti microbiologici di ventricine differentemente preparate, seguendo scrupolosamente la ricetta tradizionale o mediante triturazione meccanica della carne. In particolare, con tale ricerca è stata studiata l’influenza delle dimensioni dei pezzi di carne utilizzati ai fini della produzione sul processo di fermentazione delle ventricine oggetto di studio. I risultati hanno mostrato in entrambi i lotti una simile evoluzione della popolazione microbica. Tuttavia i ceppi isolati durante la maturazione hanno evidenziato differenti caratteristiche tecnologiche in relazione al lotto di appartenenza. Lactobacillus sakei e Streptococcus equorum sono risultate le specie maggiormente rappresentative in tutti i campioni durante tutto il periodo di maturazione. Mediante SDS-Page è stato possibile evidenziare come l’attività proteolitica sia una caratteristica propria del ceppo isolato. Tuttavia, è stata evidenziata una relazione tra l’effettiva attività sulle proteine sarcoplasmatiche e il tempo e/o il lotto da cui ogni ceppo è stato isolato. Pertanto è possibile asserire che la tecnologia di produzione potrebbe influenzare la selezione di ceppi che, pur se appartenenti alla stessa specie, sono dotati di caratteristiche tecnologiche diverse.Ventricina produced at the boundary between Abruzzo and Molise, two Italian regions, is a fermented sausage prepared with pork meat and fat chopped in cubes and abundantly spicy by sweet and hot pepper. This PhD thesis dealt with the study of microbiological aspects of two different type of Ventricina salami, produced with the traditional recipe or with meat grinding. In particular, the research was planned in order to investigate the influence of the meat size on the fermentation process. Results showed a similar microbial composition in the two type of Ventricina but strains isolated during the ripening evidenced different technological features, depending on the batch of isolation. Lactobacillus sakei and Streptococcus equorum were the main representatives species in all samples during all time of ripening. The SDS-Page evidenced that the proteolytic capability is a strain-specific character. Moreover, a relationship between the effectiveness of the action on sarcoplasmic proteins and the age and/or batch of isolation of each strain was found. Data obtained demonstrated that the technology of production could select strains belonging to the same species but characterised by different features.Dottorato di ricerca in Biotecnologia degli Alimenti (XXII ciclo
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
Natural compounds: effect on food-related microorganisms and potential use in fermented meats
No full textLe azioni illustrate nella presente tesi di dottorato hanno inteso individuare composti naturali da impiegare nella preparazione di prodotti carnei fermentati, in alternativa agli additivi chimici tradizionali, che siano in grado di inibire lo sviluppo dei microrganismi indesiderati senza condizionare la crescita di quelli virtuosi. L’efficacia e lo spettro di azione di 8 differenti composti naturali sono stati valutati nei confronti di differenti microrganismi sia utili sia indesiderati. Attenzione particolare è stata rivolta ai fenomeni di resistenza, sensibilità, nonché di adattamento esibiti da tali microrganismi rispetto ai composti naturali. A tal fine sono stati valutati eventuali variazioni dei caratteri strutturali delle cellule microbiche, quali l’espressione delle proteine totali, indotte dalla presenza dei composti naturali.
La puntuale comprensione degli effetti esplicati dai singoli composti sui microrganismi utili e indesiderati ha condotto alla selezione di quei composti candidabili all’impiego nella preparazione di prodotti carnei fermentati e ha consentito la formulazione di una miscela di sostanze naturali in possesso di attività antimicrobica selettiva ed ottimale. L’efficacia di tale miscela è stata validata nella preparazione di insaccati fermentati attraverso prove condotte su scala pilota.The aim of this PhD thesis was to identify natural compounds, alternative to antimicrobial chemical additives, to be used in the fermented meat industry. The effect of 8 natural compounds and their spectrum of action was evaluated on different microorganisms, both spoilage and useful ones. The efficacy of natural compounds was evaluated not only in terms of microbial resistance and susceptibility, but also in terms of adaptability of assayed microorganisms to the presence of each compound. This study was performed through the investigation of possible alterations in their whole cell protein expression induced by the presence of natural compounds.
Data obtained allowed the selection of those natural compound suitable for the meat industry, that is able to inhibit spoilage microorganisms without affecting the growth of useful ones. Moreover a natural mixture, composed of selected compounds, was individuated and its efficacy was verified in a pilot scale for the production of fermented sausages.Dottorato di ricerca in Biotecnologia degli Alimenti (XXIII ciclo
A proteomic study of “Coppa Piacentina”: A typical Italian dry-cured Salami
No full textCoppa Piacentina is considered a peculiar dry cured salami, since it is manufactured by the entire neck muscles stuffed and matured in natural casings, the same as dry cured ham and fermented dry cured sausages. In this work the proteolysis of external and internal portions was investigated by a proteomic approach and by amino acids analysis. Samples of "Coppa Piacentina" were analyzed at 0 days and after 5 and 8 months of ripening through mono-and two-dimensional gel electrophoresis. Image analysis of 2D electrophoretic maps indicated a more intense enzyme activity on the external part, mainly due to endogenous enzymes. They favored, respec-tively, myofibrillar or sarcoplasmic proteins at 5 or 8 months of ripening. Free amino acids determination proved that lysine and glutamic acid were the most represented ones, followed by a free amino acids sequence like that of dry cured ham. The peculiarities of "Coppa Piacentina" were characterized by a slow proteolysis, due to sacking and binding of the whole cut of the pork neck
Influence of starter cultures and KCl on some biochemical, microbiological and sensory features of soppressata molisana, an Italian fermented sausage
No full textThe effect of a multiple strain starter (KSL: Kocuria varians, Staphylococcus xylosus and Lactobacillus sakei) on the quality of soppressata molisana was investigated during 50 days of ripening. When compared with control batches (C, traditional production without starter and KS, addition of K. varians and S. xylosus as starter), soppressata produced with KSL showed positive results in terms of proteolysis progression, reduction of biogenic amines (BA) and sensory features. The partial substitution of 50 % NaCl with 50 % KCl further improved the quality of soppressata molisana produced with KSL as starter. In fact, the K+ ions seemed to stimulate the growth of added bacteria, with a resulting additional lowering of the pH and BA formation, and higher proteolysis. Moreover, the addition of KCl did not alter the sensory profile of final products. The analysis of data collected during the fermentation and the drying phases, which followed one other, allowed the individuation of different proteolytic events. Specifically, the proteolysis of the myofibrillar fraction occurred more slowly than that of the sarcoplasmic one. Also, the analysis of fractionated muscle proteins allowed to appreciate that sarcoplasmic proteins were hydrolyzed by both endogenous and microbial enzymes, whereas myofibrillar proteins showed a higher resistance to microbial enzymes, and were primarily hydrolyzed by endogenous ones. In conclusion the combined use of KSL and KCl as partial substitute of NaCl, allowed the production of soppressata molisana having an excellent quality, and features consistent with the guidelines of WHO on the sodium and potassium intake
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
- …
