1,720,995 research outputs found
La gestione microbiologica delle batterie
No full textIl processo di produzione dell’aceto balsamico tradizionale prevede quattro fasi distinte: cottura del mosto, fermentazione alcolica, fermentazione acetica ed invecchiamento. Ognuna di queste fasi va gestita attentamente sulla base di fattori sia di tipo chimico-fisico che microbiologico. Data la scalarità delle fasi, le anomalie presenti a monte del processo si ripercuotono sul prodotto finale. Ad esempio, le fermentazioni spontanee sono tra le principali cause di variabilità e di insuccesso ed è per tal motivo che occorre un accurato monitoraggio della batteria che possa preventivamente correggere eventuali irregolarità nel sistema. In particolare, i parametri da monitorare durante la gestione della batteria sono: l’acidità titolabile, la concentrazione alcolica, il pH, la temperatura e l’ossigeno. L’impiego di colture starter di lieviti e batteri acetici selezionate sulla base dei caratteri desiderabili può essere utile per la standardizzazione del processo e per l’ottenimento di un prodotto che presenti le proprietà chimico-organolettiche richiest
Influenza della composizione del mezzo sull’attività biologica dell’ABT.
No full textLa composizione del mosto cotto esercita una forte pressione selettiva sui microrganismi presenti determinando la prevalenza di lieviti o batteri acetici in funzione della combinazioni di variabili quali, il pH, la concentrazione in solidi solubili, la presenza di etanolo o di acido acetico. In sei differenti composizioni del mezzo ottenuti variando la percentuale di mosto cotto e mosto fresco d’uva, sono stati osservati andamenti fermentativi significativamente diversi, ma riconducibili a due tipologie: una a prevalente attività fermentativa ad opera di lieviti fruttosofili e l’altra a prevalente attività ossidativa ad opera di batteri acetici. Ciò che sembra maggiormente determinare lo sviluppo di lieviti o di batteri è la concentrazione zuccherina iniziale. Concentrazioni del mezzo superiori ai 30 °Brix, in presenza di acido acetico (1% circa) e valori di pH bassi, imprimono una forte pressione selettiva che consente lo sviluppo di poche specie di lievito, prevalentemente fruttosofile, ma non dei batteri acetici. Al contrario concentrazioni di solidi solubili inferiori a 30 °Brix non inibiscono lo sviluppo dei batteri acetici. Inoltre, alcuni prodotti del metabolismo microbico possono essere impiegati come indicatori indiretti della prevalenza di un determinato gruppo nel processo fermentativo
Acetic acid bacteria of traditional balsamic vinegar.
No full textAims: Traditional Balsamic Vinegar has been made by the ageing of cooked grape must into wooden barrels arranged in set of 5-7 casks each of varying capacity. Every year a small amount of vinegar is transferred from a bigger to a smaller barrel and new cooked must is added to the first barrel of the set. In this way the sugary concentration is increased from the biggest to the smallest barrel due to water evaporation across the wood.Methods and results: Different molecular techniques were applied to study acetic acid bacteriain Traditional Balsamic Vinegar. In particular 16S-23S-5S rDNA PCR/RFLP analysis, DGGE and sequencing techniques were performed on both acetic acid bacteria type strains and isolated strains from vinegars.Conclusion: Gluconacetobacter xylinus is the main species of Traditional Balsamic Vinegar and the greatest hurdle to the growth of acetic acid bacteria is high sugar concentration.Significance and impact of the study: The results suggest new technological approach to vinegar production
Detection of Acetic Acid Bacteria in Traditional Balsamic Vinegar by PCR-DGGE analysis
No full textThe denaturing gradient gel electrophoresis (DGGE) applied to PCR products of relatively conserved regions in the genome is a well documented culture-independent method to study microbial communities. In the present study we used DGGE to evaluate acetic acid bacteria population of Traditional Balsamic Vinegar which is, to our knowledge, a system not investigated with this approach previously. The results obtained suggest that PCR-DGGE is clearly a suitable tool for a rapid and cost effective screening of acetic acid bacteria in vinegar’s samples
Molecular assessment of indigenous yeast population from traditional balsamic vinegar
No full textAims: To identify and describe the indigenous yeast population involved in traditional balsamic vinegar (TBV) fermentation. Methods and Results: Using the restriction analysis of the ribosomal region 5(.)8S (5.8S rRNA) and the internal transcribed spacers 1 and 2 (5(.)8S-ITS region) we were able to group 133 strains isolated from 17 cooked grape must samples into 10 different yeast species, included into 4 genera. Moreover, we sequenced the D1/D2 domains of the 26S rRNA and confirmed the reliability of each identification at species level. Most strains belonged to the genus Zygosaccharomyces. In particular, Zygosaccharomyces bailii was found in 41% of the samples, followed by Saccharomyces cerevisiae, Zygosaccharomyces pseudorouxii and Candida stellata. Strains belonging respectively to Zygosaccharomyces mellis, Zygosaccharomyces bisporus, Zygosaccharomyces rouxii, Hanseniaspora valbyensis, Hanseniaspora osmophila and Candida lactis-condensi species were also detected. Despite the great number of species recovered, the mtDNA restriction profiles showed low variability at strain level. Saccharomyces cerevisiae isolates with an higher degree of intraspecific variance were considered an exception. Conclusions: Many different indigenous yeast species were recovered and TBV yeasts population seems to be far more complex than what was reported in previous literature. Significance and Impact of the Study: This study has allowed us to gain a better understanding of the indigenous yeast species of TBV cooked must
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
Is floristic quality assessment reliable in human-managed ecosystems?
No full textThe Floristic Quality Analysis (FQA) is a method to assess the quality of a flora based on the assignment of scores to plant species and subsequent calculation of indices. This method is widely applied, but inadequate investigation has been devoted to test its potential problems due to human factors. This work is aimed to specifically test how the human factor can affect the calculation of the FQA indices, by addressing three questions: (i) Are the scores given to plant species consistent among different experts?; (ii) Are the floristic quality indices calculated by different experts consistent in ordering individual sites?; and (iii) Does the use of an appropriate statistics change the ordering of individual sites? To answer these questions, a list of species obtained in 136 plots in central Italy was submitted to nine experts, who scored each species. The FQA indices were then calculated from the scores of each of the experts. The results showed that: (i) the scores given to the species by the experts were not consistent and the derived floristic quality indices were statistically different; (ii) the floristic quality indices calculated for each plot were significantly different among experts, but the ranking of these plots based on their floristic quality was rather consistent; and (iii) the use of ordinal statistics, which is more adequate for this type of data, did not change the results. This study demonstrated that the Floristic Quality Analysis does not provide reliable and objective tools to assess the quality of the flora in a human-managed ecosystem. The application of these indices should be preceded with resolution of the methodological problems associated with the use of inappropriate statistics, and by procedures to reduce the degree of subjectivity in assigning the CC scores
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