1,720,976 research outputs found
Influence of cheese making process on STEC bacteriophage release
Full text linkShiga toxin-producing Escherichia coli (STEC) are foodborne pathogens implicated in diseases including hemolytic uremic syndrome (HUS) and hemorrhagic colitis (HC). The main virulence factor are Shiga toxins; their production and secretion are by-products of the expression of late genes of prophages upon sub-lethal environmental stimuli exposure. Hence, the lysogenic prophage after a stress switch to lytic cycle spreading the Stx phages. In the present study, 35 STEC were screened for the presence and the ability to release Shiga toxin-encoding bacteriophages. Three bacterial strains showed signals of prophage presence both in plate and in PCR. Subsequently, these bacterial strains were subjected to stressors that simulate cheese manufacturing conditions: NaCl (1, 1.5 and 2% w/v), lactic acid (0.5, 1.5 and 3% v/v), anaerobic growth, pasteurization (72°C for 15 s), UV irradiation. The ability to release prophage was evaluated by Real Time qPCR. Induction of the prophages showed that the addition of NaCl at 1.5 and 2% significantly increased viral release compared to control. Conversely, the addition of lactic acid had a significant repressive effect. The other applied stressors had no significant effect in phage release according to the experimental conditions adopted
Shaping the structure of blends from sunflower press cake and whey proteins through heat treatment and fermentation
No full textThe current food system suffers from the inefficient use of resources, including the generation of side streams of low economic value, but still containing nutritional components. One potential approach to reach a more sustainable food system is to reintroduce such side streams into a circular value chain, and valorise them in novel food products, preferably in an unrefined or minimally refined manner. Moreover, blending side streams from different industries might be a suitable way to exploit functional synergies of structuring components such as proteins and polysaccharides, and to improve the nutritional value of the final food matrix. In this study, we combined the side streams from sunflower oil production (i.e., sunflower seed press cakes) and cheese manufacture (i.e., whey and whey proteins) to obtain novel food matrices containing valuable proteins, structuring polysaccharides, as well as lactose and minerals facilitating the fermentation.
Press cake, whey powder, and whey protein concentrate were dispersed in milk ultrafiltrate to prepare different blends with varying sunflower protein to whey protein ratio (100:0–0:100) but equal dry matter (~26%) and protein content (~10%). Structure formation as a function of heating temperature was studied by heating the blends to 80, 120, or 140 °C in a Rapid Visco Analyser (RVA), either undisturbed or under continuous, moderate shear applied by a paddle rotating at 160 rpm. The bulk viscosity of the unheated blends increased with increasing press cake concentration (0–22.5%) due to the higher polysaccharide to protein ratio. As observed from the torque profiles measured by the RVA, heat treatment at 120 and 140 °C increased the viscosity of the blends. A lower heating temperature, 80 °C, barely affected the sunflower components, but resulted in some denaturation of whey proteins, thereby increasing the viscosity of blends low in press cake and high in whey proteins. Confocal microscopy revealed that undisturbed heating at 120 and 140 °C resulted in the formation of a homogeneous gel network, whereas heating under moderate shear fostered the formation of a more heterogeneous structure, with protein aggregates dispersed in a continuous matrix.
Fermentation trials using three different co-cultures, each comprising one strain of lactic acid bacteria and one yeast strain, were conducted on the blend with the highest press cake content (22.5%) for maximum valorisation of the side stream. The samples were heated in an autoclave at 120 °C for 5 min without agitation prior to inoculation, as a homogeneous structure was assumed favourable for the fermentation. The pH development during fermentation at 26 °C was recorded, and samples were withdrawn for analysis after 12, 24, and 48 h. Small amplitude oscillatory shear rheology showed no significant changes in the storage modulus with fermentation, and confocal microscopy revealed a homogeneous microstructure for the unfermented and all fermented blends. This research provides important insights in the structure formation during processing of biomacromolecule blends and shows the potential of fermentation as a mean to stabilise side stream blends and modulate their sensory properties while only minimally affecting their physical appearance
Turning poop into gold? Fermentation and Extrusion for Increasing the Value of Sunflower Seed Press Cakes and Cheese Whey
No full textPreparation of Side Stream Blends. Fermentation Trials after strains selection. Cell Growth and Acidification. Metabolisation of Sugars & Effect on Proteins. Post-Fermentation Processing Trials. Low Moisture Extrusion. Investigation on Techno-Functional Properties. Extrudates – Structure Formation under Heat. Blends of sunflower seed press cakes and cheese whey were successfully fermented with lactic acid bacteria and yeasts. Fermentation of the blends changed their colour and increased their oil and water binding capacity. Low moisture extrusion barely affected the colour of the blends, but limited heat-induced structure formation
Assessment of Microbial Populations in the Manufacture of Vacuum-Packaged Ready-to-Eat Roast Beef and in a Related Production Plant
No full textSome microbiological criteria were monitored for 6 months in vacuum-packaged roast beef (15 production batches), raw
beef (10 batches), and other meat products (12 batches) produced in an Italian small to medium-size enterprise. Fifty-five
environmental swab samples also were analyzed. The main bacterial groups were identified by cultural methods according to
International Organization for Standardization standards. Listeria monocytogenes was enumerated with the most-probablenumber
protocol, and species identification was confirmed with a specific PCR assay. Immediately after vacuum packaging, all
ready-to-eat (RTE) products had low mean aerobic colony counts (,102 to 2.43102 CFU g1), anaerobic colony counts (1.6 to
6.5 3 101 CFU g1), Enterobacteriaceae counts (1.1 to 1.4 3 101 CFU g1), and Escherichia coli counts (generally below the
detection limit). Nevertheless, the prevalence of L. monocytogenes in these samples was 3.7%. In roast beef samples, the aerobic
and anaerobic colony counts reached unacceptable levels (.106 CFU g1) after 14 days of refrigerated storage. Because the
prevalence of L. monocytogenes increased to 13.3% during storage, a substantial reduction in the shelf life of these products is
recommended. Surfaces without direct contact with food (floors and drains) had the highest mean counts for aerobic colonies (8.0
3103 to 9.53105 CFU/cm2), anaerobic colonies (2.93103 to 3.23104 CFU/cm2), Enterobacteriaceae (1.53101 to 8.43101
CFU/cm2), and E. coli (6.0 to 7.7 CFU/cm2). The levels of L. monocytogenes on direct food contact surfaces were below the
detection limit, but more than 25% of floor samples were contaminated. These results reveal the persistence of L. monocytogenes
in food processing environments, although at very low levels, posing a high risk of postcooking recontamination for RTE
products. To improve hygienic conditions and reduce cross-contamination, an increase in operator awareness and a reassessment
of surface sanitization protocols are needed
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
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