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81.
Latorre AA Pradhan AK Van Kessel JA Karns JS Boor KJ Rice DH Mangione KJ Gröhn YT Schukken YH 《Journal of food protection》2011,74(8):1268-1281
The objectives of this study were to estimate the risk of illness for raw milk consumers due to Listeria monocytogenes in raw milk sold by permitted dealers, and the risk for people on farms who consume raw milk. Three scenarios were evaluated for raw milk sold by dealers: raw milk purchased directly from bulk tanks, from on-farm stores, and from retail. To assess the effect of mandatory testing of raw milk by regulatory agencies, the number of listeriosis cases per year was compared where no raw milk testing was done, only a screening test to issue a permit was conducted, and routine testing was conducted and milk was recalled if it was L. monocytogenes positive. The median number of listeriosis cases associated with consumption of raw milk from bulk tanks, farm stores, and retail for an intermediate-age population was 6.6 × 10(-7), 3.8 × 10(-5), and 5.1 × 10(-5) cases per year, respective ly. In populations with high susceptibility, the estimated median number of cases per year was 2.7 × 10(-7) (perinatal, i.e., pregnant women and their fetuses or newborns) and 1.4 × 10(-6) (elderly) for milk purchased from bulk tanks, 1.5 × 10(-5 ) (perinatal) and 7.8 × 10(-5) (elderly) for milk from farm stores, and 2.1 × 10(-5) (perinatal) and 1.0 × 10(-4) (elderly) for milk from retail. For raw milk consumed on farms, the median number of listeriosis cases was 1.4 × 10(-7) cases per year. A greater risk of listeriosis was associated with consumption of raw milk obtained from retail and farm stores as compared with milk obtained from bulk tanks. This was likely due to additional time-temperature combination steps in the retail and farm store models, which increased the chances for growth of L. monocytogenes in raw milk. A close relationship between prevalence of L. monocytogenes in raw milk and the values of disease incidence was observed. Hence, a reduction in the number of cases per year in all populations was observed when a raw milk-testing program was in place, especially when routine testing and recalling of milk was conducted. 相似文献
82.
We study the TiO2 (Ti4+) chemical reduction induced by electron bombardment using Auger electron spectroscopy and factor analysis. We show that the electron irradiation of a TiO2 sample is characterized by the appearance of a lower Ti oxidation state, Ti2O3 (Ti3+), followed by a further deposition of carbon, which is present inevitably in the environment even under ultra-high vacuum conditions. The appearance of C over the surface is found to be a complex mechanism which affects the reduction process through passivation of the electron-induced oxygen desorption and formation of titanium carbide. For very high irradiation doses, we also found that the chemical changes on the surface are stopped due to the deposition of carbon in a graphitic form. 相似文献
83.
Francisco J. Rodríguez Alejandra Torres Ángela Peñaloza Hugo Sepúlveda María J. Galotto Abel Guarda 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2014,31(3):342-353
Nanocomposites based on biopolymers have been recognised as potential materials for the development of new ecofriendly food packaging. In addition, if these materials incorporate active substances in their structure, the potential applications are much higher. Therefore, this work was oriented to develop nanocomposites with antimicrobial activity based on cellulose acetate (CA), a commercial organoclay Cloisite30B (C30B), thymol (T) as natural antimicrobial component and tri-ethyl citrate (TEC) as plasticiser. Nanocomposites were prepared by a solvent casting method and consisted of 5% (w/w) of C30B, 5% (w/w) of TEC and variable content of T (0%, 0.5% and 2% w/w). To evaluate the effect of C30B into the CA matrix, CA films without this organoclay but with T were also prepared. All nanocomposites showed the intercalation of CA into the organoclay structure; furthermore this intercalation was favoured when 2% (w/w) of T was added to the nanocomposite. In spite of the observed intercalation, the presence of C30B inside the CA matrices increased the opacity of the films significantly. On the other hand, T showed a plasticiser effect on the thermal properties of CA nanocomposites decreasing glass transition, melting temperature and melting enthalpy. The presence of T in CA nanocomposites also allowed the control de Listeria innocua growth when these materials were placed in contact with this Gram-positive bacterium. Interestingly, antimicrobial activity was increased with the presence of C30B. Finally, studies on T release showed that the clay structure inside the CA matrix did not affect its release rate; however, this nanofiller affected the partition coefficient KP/FS which was higher to CA nanocomposites films than in CA films without organoclay. The results obtained in the present study are really promising to be applied in the manufacture of food packaging materials. 相似文献
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86.
Alejandra Cardelle-Cobas Patrícia J. M. Reis Eduardo Costa Manuela E. Pintado 《国际聚合物材料杂志》2019,68(9):481-488
Chitosan-impregnated gutta-percha points (ChitGPP) were tested for their ability to inhibit the growth of microorganisms usually involved in root canal infections. Their mechanical properties were also studied and compared with the commonly used commercial points in endodontics. ChitGPP were more efficient in reducing the microbial load than those without chitosan. ChitGPP also possess better tensile and elastic properties than commercial ones. After six months of storage, ChitGPP’s were still able to reduce the bacterial load by 1 log, suggesting that impregnation of gutta-percha points with chitosan could be a good alternative to obtain gutta-percha points with improved antimicrobial properties. 相似文献
87.
Ma. de la Paz Xavier Cecilia Dauber Paula Mussio Enrique Delgado Ana Maquieira Alejandra Soria Ana Curuchet Rosa Márquez Carlos Méndez Tomás López 《Meat science》2014
The objectives of the present work were to assess the use of moderate doses of gamma irradiation (2 to 5 kGy) and to reduce the risk of pathogen presence without altering the quality attributes of bovine trimmings and of patties made of irradiated trimmings. Microbiological indicators (coliforms, Pseudomonas spp and mesophilic aerobic counts), physicochemical indicators (pH, color and tiobarbituric acid) and sensory changes were evaluated during storage. 5 kGy irradiation doses slightly increased off flavors in patties. Two pathogenic markers (Listeria monocytogenes and Escherichia coli O157:H7) were inoculated at high or low loads to trimming samples which were subsequently irradiated and lethality curves were obtained. Provided that using irradiation doses ≤ 2.5 kGy are used, reductions of 2 log CFU/g of L. monocytogenes and 5 log CFU/g of E. coli O157:H7 are expected. It seems reasonable to suppose that irradiation can be successfully employed to improve the safety of frozen trimmings when initial pathogenic bacteria burdens are not extremely high. 相似文献
88.
89.
Esteban Avigliano Marc Pouilly Facundo Vargas Jerry Penha Natalia Silva Julien Bouchez Sebastian Sánchez Alejandra V. Volpedo 《河流研究与利用》2023,39(5):887-896
The Manguruyú Zungaro jahu, endemic to the La Plata Basin, is one of the largest neotropical fish species whose life history is virtually unknown. The objectives of this study were to determine if Z. jahu is a large-scale migratory species and to describe habitat use throughout ontogeny using the otolith Sr isotope (87Sr/86Sr) ratio. Surface water samples were collected in 2020 at four sites representing the main water courses of the Great Pantanal in Brazil (upper Paraguay, Cuiabá, São Lourenço and Vermelho rivers). Eighteen fish individuals were collected from the Paraná River (Argentina). New water 87Sr/86Sr data were incorporated into previously established statistical models to infer the fish habitat use through the otolith 87Sr/86Sr ratios. The water 87Sr/86Sr ratio of the upper Paraguay tributaries varied (0.7209 and 0.7229) and were the highest in the La Plata Basin. The dispersal area of Z. jahu was restricted to the surroundings of the confluence of the Paraná and Paraguay rivers. Fish showed chemical signatures compatible with those of the middle Paraná (88%), Paraguay-Pilcomayo-Bermejo (50%) and the lower/upper Paraná (66%). The discriminant analysis based on otolith core indicated natal origins from the middle Paraná (37%), upper Paraná (32%), and Paraguay sub-basin (32%). The dispersal area of Z. jahu migrations could be restricted to the surroundings of the confluence of Paraná and Paraguay, which highlights the need to review regional fishing regulations, especially between latitudes 30°–34° S. 相似文献
90.