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Esopolisaccaridi di origine microbica come postbiotici per lo sviluppo di nuovi alimenti funzionali
No full textExopolysaccharides of microbial origin provide, thanks to their technological and functional properties, an extraordinary opportunity for the development of new food products with high added value. Although microbial EPS are known to enhance the sensory and health-related characteristics of foods, it is still a field that requires further scientific analysis, especially in relation to the need to increase yields and clarify some aspects related to their interactions with the gut microbiota. Thus, the primary goal of this Ph.D. project was to isolate and characterize novel microbial EPS produced by LAB with desirable bioactivities for the development of new functional food products.
First, LAB were isolated from fermented foods and screened for EPS production to identify the highest performers (Chapter 2). Through a qualitative and quantitative approach, twelve strains of LAB, including Lb. plantarum, Lb. paracasei, Lc. lactis, and Leuc. mesenteroides, were identified, which could produce more than one gram of EPS per liter.
The initial step of the research has revealed three Leuconostoc strains that produced the highest yields. These strains have been used as the basis of Chapter 3, Chapter 4, and Chapter 5, where the EPS were analyzed in-depth with regards to their chemical, morphological, and functional properties.
An EPS produced by Leuc. mesenteroides B3, isolated from an Italian semi-hard cheese, was identified as a mixture of two dextrans having different Mw. This EPS was shown to have potential as an antimicrobial and antibiofilm agent, especially against L. monocytogenes. It also stimulated bifidobacteria, potentially making them more robust during food processing and storage (Chapter 3).
This EPS from Leuc. mesenteroides F02A5, isolated from raw milk cheese, is a high-Mw dextran with a linear structure. EPS displayed antimicrobial activity against some foodborne pathogens, as well as radical scavenging capacity. Moreover, the polymer was characterized by high solubility and capacity to retain water, which could be very useful in specific food formulations (Chapter 4).
Leuc. mesenteroides PM01A5 strain, isolated from sourdough, produced an EPS made of a mixture of dextran and levan. This polymer exhibited antimicrobial activity and particularly stood out for its strong antioxidant potential (Chapter 5).
At the end of the exploration of the potential of microbial EPS, in collaboration with the research group supervised by Prof. Paul Cotter, from the Food Bioscience Dept. of Teagasc Food Research Centre, Cork, Ireland, two of the most promising EPS were used to enrich a fermented soy beverage. One of them was shown to drastically increase the alpha diversity of the gut microbial community during an ex vivo faecal fermentation, also stimulating the proliferation of the beneficial bacterial species Bif. adolescentis, Bif. longum, A. hardus, and F. praustnizii, therefore offering exciting prospects for potential functional uses (Chapter 6).
Finally, in an effort to improve EPS yields, the impact of both traditional and non-traditional strategies was examined. It was found that an initial pH of 8, which is significantly higher than the optimal, can greatly stimulate EPS biosynthesis in most strains. The use of pretreatments with MIPEF was also identified as a highly promising strategy, resulting in a production increase of EPS by at least eight times (Chapter 7).Exopolysaccharides of microbial origin provide, thanks to their technological and functional properties, an extraordinary opportunity for the development of new food products with high added value. Although microbial EPS are known to enhance the sensory and health-related char-acteristics of foods, it is still a field that requires further scientific analysis, especially in relation to the need to increase yields and clarify some aspects related to their interactions with the gut microbiota. Thus, the primary goal of this Ph.D. project was to isolate and characterize novel microbial EPS produced by LAB with desirable bioactivities for the development of new func-tional food products.
First, LAB were isolated from fermented foods and screened for EPS production to identify the highest performers. Through a qualitative and quantitative approach, twelve strains of LAB, in-cluding Lb. plantarum, Lb. paracasei, Lc. lactis, and Leuc. mesenteroides, were identified, which could produce more than one gram of EPS per liter. Some of these strains were selected for further re-search (Chapter 2).
In an effort to improve EPS yields, the impact of both traditional and non-traditional strategies was examined. It was found that an initial pH of 8, which is significantly higher than the opti-mal, can greatly stimulate EPS biosynthesis in most strains. The use of pretreatments with MIPEF has been also identified as a highly promising strategy, resulting in a production increase of EPS by at least eight times (Chapter 3).
The results of these first steps have shone the spotlight on three strains, whose EPS were sub-jected to an in-depth chemical, morphological, and functional characterization.
An EPS produced by Leuc. mesenteroides B3, isolated from an Italian semi-hard cheese, was iden-tified as a mixture of two dextrans having different Mw. This EPS showed to have potential as an antimicrobial and antibiofilm agent, especially against L. monocytogenes. It also stimulated bifidobacteria, potentially making them more robust during food processing and storage (Chap-ter 4).
EPS from Leuc. mesenteroides F02A5, isolated from raw milk cheese, is a high-Mw dextran with a linear structure. EPS displayed antimicrobial activity against some foodborne pathogens, as well as radical scavenging capacity. Moreover, the polymer was characterized by high solubility and capacity to retain water, which could be very useful in specific food formulations (Chapter 5).
Leuc. mesenteroides PM01A5 strain, isolated from sourdough, produced an EPS made of a mixture of dextran and levan. This polymer exhibited antimicrobial activity and particularly stood out for its strong antioxidant potential (Chapter 6).
At the end of this path of exploration of the potential of microbial EPS, in collaboration with the research group supervised by Prof. Paul Cotter, from the Food Bioscience Dept. of Teagasc Food Research Centre, Cork, Ireland, two of the most promising EPS were used to enrich a soymilk fermented beverage. One of them was shown to drastically increase the alpha diversity of the gut microbial community during an ex vivo faecal fermentation, also stimulating the prolif-eration of the beneficial bacterial species Bif. adolescentis, Bif. longum, Anaerostipes hardus, and Fae-calibacterium praustnizii, therefore offering exciting prospects for potential functional uses (Chapter 7)
Microbial exopolysaccharides as postbiotics for the development of new functional foods: optimization of yields
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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
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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