124 research outputs found

    Animal rennets as sources of dairy lactic acid bacteria

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    The microbial composition of artisan and industrial animal rennet pastes was studied by using both culture-dependent and -independent approaches. Pyrosequencing targeting the 16S rRNA gene allowed to identify 361 operational taxonomic units (OTUs) to the genus/species level. Among lactic acid bacteria (LAB), Streptococcus thermophilus and some lactobacilli, mainly Lactobacillus crispatus and Lactobacillus reuteri, were the most abundant species, with differences among the samples. Twelve groups of microorganisms were targeted by viable plate counts revealing a dominance of mesophilic cocci. All rennets were able to acidify ultrahigh-temperature-processed (UHT) milk as shown by pH and total titratable acidity (TTA). Presumptive LAB isolated at the highest dilutions of acidified milks were phenotypically characterized, grouped, differentiated at the strain level by randomly amplified polymorphic DNA (RAPD)-PCR analysis, and subjected to 16S rRNA gene sequencing. Only 18 strains were clearly identified at the species level, as Enterococcus casseliflavus, Enterococcus faecium, Enterococcus faecalis, Enterococcus lactis, Lactobacillus delbrueckii, and Streptococcus thermophilus, while the other strains, all belonging to the genus Enterococcus, could not be allotted into any previously described species. The phylogenetic analysis showed that these strains might represent different unknown species. All strains were evaluated for their dairy technological performances. All isolates produced diacetyl, and 10 of them produced a rapid pH drop in milk, but only 3 isolates were also autolytic. This work showed that animal rennet pastes can be sources of LAB, mainly enterococci, that might contribute to the microbial diversity associated with dairy productions

    Understanding systematic reviews : the meta-analysis graph (also called 'forest plot')

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    Mammographic screening for breast cancer is controversial, as reflected in greatly varying national policies. The objective was to assess the effect of screening for breast cancer with mammography on mortality and morbidity. MEDLINE (16 May 2000), The Cochrane Breast Cancer Group's trial register (24 Jan 2000) and reference lists. Letters, abstracts and unpublished trials. Authors were contacted. Randomised trials comparing mammographic screening with no mammographic screening. Data were extracted by both authors independently. Seven completed and eligible trials involving half a million women were identified. The two best trials provided medium-quality data and, when combined, yield a relative risk for overall mortality of 1.00 (95% CI 0.96-1.05) after 13 years. However, the trials are underpowered for all-cause mortality, and confidence intervals include a possible worthwhile effect as well as a possible detrimental effect. If data from all eligible trials (excluding flawed studies) are considered then the relative risk for overall mortality after 13 years is 1.01 (95% CI 0.99-1.03). The best trials failed to show a significant reduction in breast cancer mortality with a relative risk of 0.97 (95% CI 0.82-1.14). If data from all eligible trials (excluding flawed studies) are considered then the relative risk for breast cancer mortality after 13 years is 0.80 (95% CI 0.71-0.89). However, breast cancer mortality is considered to be an unreliable outcome and biased in favour of screening. Flaws are due to differential exclusion of women with breast cancer from analysis and differential misclassification of cause of death. The currently available reliable evidence does not show a survival benefit of mass screening for breast cancer (and the evidence is inconclusive for breast cancer mortality). Women, clinicians and policy makers should consider these findings carefully when they decide whether or not to attend or support screening programs

    Microbial activation of wooden vats used for traditional cheese production and evolution of the neoformed biofilms

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    Three Lactococcus lactis subsp. cremoris strains were used to develop ad hoc biofilms on the surfaces of virgin wooden vats used for cheese production. Two vats (TZ) were tested under controlled conditions (pilot plant), and two vats (TA) were tested under uncontrolled conditions (industrial plant). In each plant, one vat (TA1 and TZ1) was used for the control, traditional production of PDO Vastedda della Valle del BelĂŹce (Vastedda) cheese, and one (TA2 and TZ2) was used for experimental production performed after lactococcal biofilm activation and the daily addition of a natural whey starter culture (NWSC). Microbiological and scanning electron microscopy analyses showed differences in terms of microbial levels and composition of the neoformed biofilms. The levels of the microbial groups investigated during cheese production showed significant differences between the control trials and between the control and experimental trials, but the differences were not particularly marked between the TA2 and TZ2 productions, which showed the largest numbers of mesophilic lactic acid bacterium (LAB) cocci. LAB populations were characterized phenotypically and genotypically, and 44 dominant strains belonging to 10 species were identified. Direct comparison of the polymorphic profiles of the LAB collected during cheese making showed that the addition of the NWSC reduced their biodiversity. Sensory evaluation showed that the microbial activation of the wooden vats with the multistrain Lactococcus culture generated cheeses with sensory attributes comparable to those of commercial cheese. Thus, neoformed biofilms enable a reduction of microbial variability and stabilize the sensorial attributes of Vastedda cheese

    Effect on the antioxidant, lipoperoxyl radical scavenger capacity, nutritional, sensory and microbiological traits of an ovine stretched cheese produced with grape pomace powder addition

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    An innovative ovine cheese enriched with red grape pomace powder (GPP) was produced to improve the functional properties of Vastedda cheese typology. Vastedda cheese making was performed adding GPP and four selected Lactococcus lactis strains (Mise36, Mise94, Mise169 and Mise190). For each strain, 40 L of pasteurized ewe’s milk was divided into two aliquots representing control and experimental trials. Control cheese (CC) production did not contain GPP, while the experimental cheese (EC) production was enriched with 1% (w/w) GPP. GPP did not slow down starter development and acid generation. Plate counts and randomly amplified polymorphic DNA (RAPD)-PCR analysis confirmed the dominance of the starters in all trials. The evolution of the physicochemical parameters showed that EC productions were characterized by lower fat content, higher protein content, and higher values of secondary lipid oxidation. Sensory evaluation indicated that the cheeses produced with the strain Mise94 were those more appreciated by the judges. Thus, the last cheeses were investigated for some functional aspects: GPP enrichment significantly increased antioxidant activity and lipoperoxyl radical scavenger capacity, confirming that grape polyphenol inclusion in cheese represents an optimal strategy for the valorization of ovine cheeses as well as winemaking industry by-products

    Spatially self-similar spherically symmetric perfect-fluid models

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    Einstein's field equations for spatially self-similar spherically symmetric perfect-fluid models are investigated. The field equations are rewritten as a first-order system of autonomous differential equations. Dimensionless variables are chosen in such a way that the number of equations in the coupled system is reduced as far as possible and so that the reduced phase space becomes compact and regular. The system is subsequently analysed qualitatively with the theory of dynamical systems.Comment: 21 pages, 6 eps-figure

    A novel microbiological approach to impact the aromatic composition of sour loquat beer

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    The growing interest in novel beer development determined the exploitation of unconventional yeasts isolated from novel ecological niches to generate unexplored sensory profiles. In recent years, there is an increasing interest in generating beers brewed with the addition of fruits. For the first time, Lachancea thermotolerans MNF105 and Saccharomyces cerevisiae MN113 isolated from manna, were tested as starter cultures to process loquat beer to improve the sensory profile. Innovatively, the yeast species L. thermotolerans was investigated for the production of sour fruit beer. Sour fruit beers produced with L. thermotolerans MNF105 were more balanced than the respective control, especially in terms of perceived acidity during sensory analysis. This could be due to the lower lactic acid production (0.49 g/L) compared to the respective control (1.74 g/L). The overall organoleptic investigation showed a preference for S. cerevisiae MN113 (TF1) isolated from manna. Experimental trials conducted with the selected strains demonstrated the absence of off-odour and off-flavour and improved aroma perception. Aldehydes and alcohols were the most abundant compounds emitted from the beers. S. cerevisiae MN113 and L. thermotolerans MNF105, manna related yeasts, showed great technological properties, representing promising starters for the production of fruit beer and sour fruit beer

    Valutazione della bontà educativa dei casi clinici di ECCE, il programma di formazione a distanza (FAD) basato sulle evidenze destinato ai medici italiani

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    OBIETTIVO. Valutare la qualit\ue0 dei percorsi clinici di un programma FAD destinato a tutti i medici italiani verificando le loro propriet\ue0 psicometriche. METODI. AIFA ha lanciato un programma nazionale di sostegno dell\u2019informazione indipendente tramite la distribuzione gratuita ai medici di Clinical Evidence (CE). Sulla base dei contenuti di CE \ue8 stato sviluppato un programma FAD all\u2019interno del sistema di Educazione Continua in Medicina (ECM) dal nome ECCE, anch\u2019esso gratuito. I medici hanno accesso a CE online e ai relativi percorsi clinici. Superandoli il medico ottiene i crediti ECM. Nel corso del 2006 \ue8 stata valutata la qualit\ue0 di un campione di venti percorsi, su un totale di 120. La valutazione formale della qualit\ue0 dei 20 casi selezionati \ue8 avvenuta attraverso le seguenti dimensioni psicometriche: Giudizio generale sui percorsi da parte degli utilizzatori (face validity); Valutazione dei contenuti da parte di clinici esperti (content validity); Valutazione della attendibilit\ue0 del test attraverso un criterio di consistenza interna (internal reliability); Difficolt\ue0 degli items; Capacit\ue0 del test di rilevare una modificazione della conoscenza (responsiveness). RISULTATI: Alcune migliaia di utenti hanno partecipato alla valutazione fornendo esiti contrastanti: mentre la face e content validity sono state valutate positivamente dagli utilizzatori e dai clinici esperti, altri parametri come l\u2019internal reliability e la difficolt\ue0 degli items hanno mostrato grande variabilit\ue0 tra i percorsi. Sette casi mostrano un valore di alpha complessivo inferiore a 0.50 (soglia minima di affidabilit\ue0). I casi si sono dimostrati nel complesso medio-facili. Facendo riferimento solo alle proprie conoscenze i partecipanti rispondevano correttamente a circa a met\ue0 delle domande. La lettura delle fonti era associata a un miglioramento della performance (miglioramento prima-dopo statisticamente significativo, p<0.05 per 19/20 percorsi). CONCLUSIONI: L\u2019importante eterogeneit\ue0 tra percorsi dimostrerebbe come differenti casi possono analizzare in maniera molto disomogenea il domino conoscenza evidence-based derivata dai contenuti di CE
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