Effect of E-beam treatment on expression of virulence and stress-response genes of Listeria monocytogenes in dry-cured ham.

Various adverse conditions can trigger defensive mechanisms in Listeria monocytogenes that can increase the virulence of surviving cells. The objective of this study was to evaluate the expression of one stress-response (sigB) and three virulence (plcA, hly, and iap) genes in L. monocytogenes exposed to a sub lethal dose of E-beam irradiation in dry-cured ham. To accomplish this, dry-cured ham slices (10 g) were immersed in a 109 CFU/mL suspension of L. monocytogenes strain S4-2 and subsequently irradiated with 1, 2, or 3 kGy. After irradiation, samples were stored at 7 °C or 15 °C for 30 days. Absolute gene expression levels were determined by RT-qPCR, and numbers of surviving Listeria cells were assessed by microbial counts after different storage times (0, 7, 15, and 30 days). At 7 °C, after E-beam treatment at doses of 2 or 3 kGy, Listeria gene expression significantly increased (p ≤ 0.05) up to day 15. Listeria counts decreased with increasing dosage. The relationship between absolute gene expression and the number of surviving Listeria cells could indicate that sublethal doses of E-beam irradiation can increase expression of the genes studied. We observed no significant influence of storage time or temperature on gene expression (p > 0.05). Listeria that survives E-beam treatment may display increased virulence, constituting a significant potential public health risk.

Use of e-beam for shelf-life extension and sanitizing of marinated pork loin.

The effectiveness of E-beam radiation to extend the shelf-life of marinated pork loin slices stored at 4 and 8°C (temperature abuse) has been studied. The shelf-life was extended from 7 to 16 and >20 days after the application of 1 and 2 kGy, respectively. In the event of a temperature abuse occuring during the product distribution (e.g., increase to 8°C), the shelf-life would be extended from 5 to 10 and 16 days, respectively, when applying the doses mentioned previously. From a public health point of view, the irradiation of marinated pork loin may be marketable for a longer period of time of up to two weeks, and guarantees a practically Salmonella and Listeria-free product. Minor changes are produced by the E-beam treatment in the main sensory and rheological characteristics. The odor was the most affected feature, but the off-odors diminished with increased storage. In any case, testers judged the samples to be adequate for marketing.

Lack of growth of Listeria monocytogenes and Staphylococcus aureus in temperature abuse of E-beam treated ready-to-eat (RTE) cooked ham.

The behaviour of Listeria monocytogenes and Staphylococcus aureus in vacuum-packed cooked ham slices treated with an electron beam and stored at 4, 7 and 10 degrees C was investigated. Cooked ham slices were inoculated with L. monocytogenes and S. aureus and electron beam treated at 2 and 3 kGy. After treatment, a long temperature-dependent death phase was observed, followed by growth at a slower rate than in untreated samples. Assuming a hypothetical load of 10 cells/g or cm(2) of L. monocytogenes and S. aureus as an original contamination in an industrial situation, an E-beam treatment of vacuum-packed cooked ham slices at 2 kGy guarantees the microbiological safety of the product along its shelf life, even if a noticeable temperature (10 degrees C) abuse occur during its storage period. Likewise, the E-beam treatment gave rise to a substantial increase of the RTE cooked ham shelf life off-sensory features associated to the spoilage only were detected in non-treated samples (controls) after 8 and 18 days of storage at 10 degrees C and 7 degrees C, respectively.

Motivos de elección de una asignatura por parte de los alumnos / Some reasons which could induce to the students to choose an academic subject

El motivo de elección de una determinada asignatura por parte de los alumnos, ha sidofrecuentemente interpretado bajo diferentes puntos de vista. En esta comunicación nuestro objetivo hasido analizar los motivos de elección en distintos tipos de asignaturas con características peculiarescada una de ellas, concretamente dos de ellas son de libre configuración, siendo una de impartición enel campus andaluz virtual –Fotoprotección- y la otra en el campus virtual de la Universidad deGranada –Aplicación de la Tecnología Farmacéutica en el tratamiento del cáncer y del dolor-. Latercera asignatura seleccionada es una optativa -Farmacia Práctica- que se imparte actualmente en laLicenciatura en Farmacia. Se ha realizado un análisis de los diferentes motivos que impulsan a unalumno a la elección de una disciplina frente a otra, para ello se ha utilizado una de las herramientas demayor uso, la encuesta anónima a todos aquellos que estaban matriculados. Las conclusiones de esteestudio son diversas pero ante todo cabe señalar en el caso de las virtuales la facilidad de acceso yrealización de las asignaturas virtuales, y destacar también que un título atractivo es fundamental en suelección. En el caso de la optativa el motivo fundamental ha sido aprender algo nuevo relacionado consu licenciatura y seguido muy de cerca por la facilidad de horario. Por tanto como conclusióndefinitiva es interesante destacar que tanto en un caso como en otro el alumno desea aprender algoatractivo y que se acomode fácilmente a su horario de estudio(AU)

The reason why a specific subject is chosen by the students has been frequently interpretedfrom several points of view. The aim of this study is to analyze the reasons why different types ofsubjects with particular characteristics are chosen. Specifically, two of these subjects are freeelectives: one of them –Fotoprotección- is imparted through the Andalusian Virtual Campus, and theother one –Aplicación de la Tecnología Farmacéutica en el tratamiento del cáncer y del dolorthroughthe virtual campus of the University of Granada. The third subject chosen is optional -Farmacia Práctica- and it is at present imparted within the Degree in Pharmacy. The different reasonswhy a student chooses one subject against other have been analyzed using one of the most used tools:an anonymous survey to all the students enrolled. The conclusions of this study are diverse, but it ismainly to be remarked in the case of the virtual subjects their accessibility and easy implementation aswell as the importance of an attractive title for the selection of a subject. The main reason in the caseof the optional subject is to learn something new in relation to their Degree, followed very closely byits timetable. Therefore, as final conclusion, it is interesting to remark that the students want in bothcases to learn something attractive that can be easily adapted to their study schedule(AU)

Creación de un espacio virtual para el apoyo de la docencia en Química Física (Farmacia) / Creation of a virtual environment for supporting the teaching in Physical-Chemistry (Pharmacy)

Un aspecto importante de la práctica docente en el EEES es su interés en el trabajo global del alumno a partir del cual se establece el sistema ECTS de créditos curriculares. Este enfoque requiere una revisión de la metodología docente.Es reconocido que la irrupción de las TIC en todos los sectores sociales, ha tenido una repercusión directa en el sistema educativo. En este contexto, Internet ha demostrado no sólo su importancia como canal de transmisión de contenidos sino su potencial como herramienta docente ya que incorpora interactividad, permite la personalización en la utilización de recursos, se adapta a necesidades particulares en el proceso formativo y permite combinar diferentes tipos de recursos.La aplicación de las TIC en la educación superior es cada día más palpable. Con las limitaciones que imponen los grupos numerosos de alumnos, es clara la tendencia hacia la creación de entornos virtuales como apoyo de la docencia presencial con una integración lo más completa posible en la programación didáctica.La presente comunicación analiza estas cuestiones desde la experiencia acumulada en el desarrollo de diversos recursos docentes y la creación de un entorno específico para algunos grupos de alumnos del curso primero adscritos a las enseñanzas impartidas por el Departamento de Química Física en su sección de Farmacia.El entorno virtual se propone como a) un espacio diseñado no como acumulación de páginas HTML, sino como estructurado de una forma flexible de manera que permita ser actualizado por aportaciones múltiples; b) un espacio interactivo que facilite tanto los intercambios más habituales: profesor-alumnos, como los intercambios transversales entre los alumnos; c) una referencia para alojar recursos que complementen la actividad presencial y d) un lugar de integración de diversas herramientas de aplicación docente(AU)

A important issue regarding the educational practice in the EEES, is the interest in the students’ global work from which curricular ECST system has been established. This particular approach requires a revision of the methodology applied in teaching.It is well known that the Information and Communication Technologies (ICT) have been extended to all social sectors and have produced a special impact on the educational system. In this context, Internet has proved to be not only important as a channel for the transmission of contents but also as a potential educational tool since incorporates interactivity, allows a personalized use of multiple resources, is adaptable to particular needs in the formative process and allows to combine different kinds of resources.The application of ICT in the University studies is more extended every day. In spite of the limitations imposed by the existence of groups formed by a high number of students, a clear trend seems to consolidate nowadays: the creation of virtual environments supporting on-site teaching and which are integrated as much as possible in the study schedules.The present communication focuses on these general aspects in relation with the experience accumulated in the development of several educational resources and the creation of a specific virtual environment for students which enrolled in Physical- Chemistry (Pharmacy section) during the past academic years.The virtual environment developed is a) a designed space not for accumulating static HTML pages but structured for allowing to update it with periodical contributions; b) an interactive space where the usual communicative exchange between students and teacher as well as between students is facilitated; c) a reference in which to incorporate complementary resources in order to support 'on site' teaching; and d) a place to integrate different tools with application in educational matters(AU)

A comparison between E-beam irradiation and high pressure treatment for cold-smoked salmon sanitation: microbiological aspects.

The effectiveness of electron beam irradiation and high pressure treatment for the sanitation of cold-smoked salmon from two points of view, microbial safety and shelf-life extension, was compared. From the response of L. monocytogenes INIA H66a to irradiation, a D value of 0.51 kGy was calculated. For samples stored at 5 degrees C, 1.5 kGy would be sufficient to attain a Food Safety Objective (FSO) of 2 log(10)cfu/g L. monocytogenes for a 35-day shelf-life, whereas 3 kGy would be needed in the case of a temperature abuse (5 degrees C + 8 degrees C). Pressurization at 450 MPa for 5 min was considered to be an insufficient treatment, since the FSO of 2 log(10)cfu/g L. monocytogenes was only attained for a shelf-life of 21 days at 5 degrees C. However, treatment at 450 MPa for 10 min achieved this FSO for samples held during 35 days at 5 degrees C, or during 21 days under temperature abuse (5 degrees C+8 degrees C) conditions. Irradiation at 2 kGy kept the microbial population of smoked salmon below 6 log(10)cfu/g after 35 days at 5 degrees C, with negligible or very light changes in its odor. Pressurization at 450 MPa for 5 min also kept the microbial population below 6 log(10)cfu/g after 35 days at 5 degrees C and did not alter odor, but affected negatively the visual aspect of smoked salmon.

Safety and quality of ready-to-eat dry fermented sausages subjected to E-beam radiation.

The inactivation kinetics in the death of Listeriainnocua NTC 11288 (more radioresistant than five different strains of Listeriamonocytogenes) and Salmonella Enterica serovar Enteritidis and S. enterica serovar Typhimurium by E-beam irradiation has been studied in two types of vacuum-packed RTE dry fermented sausages ("salchichon" and "chorizo") in order to optimize the sanitation treatment of these products. A treatment of 1.29kGy was calculated to reach the food safety objective (FSO) according to the "zero tolerance" criterion for the three strains. No irradiation treatment was necessary to meet the 10(2)c.f.u./g microbiological criterion for L. monocytogenes. Dry fermented sausages treated with ⩽2kGy had negligible sensory (appearance, odour and taste) modifications. Therefore, this treatment produces safe dry fermented sausages with similar sensory properties to the non-irradiated product.

Elimination of Listeria monocytogenes from vacuum-packed dry-cured ham by E-beam radiation.

The inactivation kinetics for Listeria monocytogenes Scott A (CIP 103575, serotype 4b) and Listeria innocua (NTC 11288) after E-beam radiation were studied in vacuum-packed ready-to-eat dry-cured ham to optimize the sanitation treatment of this product. A treatment of 1.12 kGy was calculated to reach the food safety objective according to the U.S. Department of Agriculture criterion. No irradiation treatment is necessary to meet the European Union microbiological criterion for this bacterium. No changes (at doses < or =4 kGy) in the 2-thiobarbituric acid reactive substances values and texture were observed. Dry-cured hams treated with 1 and 2 kGy had negligible sensory modifications (appearance, odor, and flavor). However, the application of 3 and 4 kGy resulted in an increase in the intensity of off-odors and off-flavors. Despite these effects, all irradiated vacuum-packed dry-cured hams treated at < or =4 kGy were deemed acceptable for trading.

Enrichment of dry-cured ham with α-linolenic acid and α-tocopherol by the use of linseed oil and α-tocopheryl acetate in pig diets.

The use of α-linolenic acid and α-tocopherol enriched pork on the fatty acids and the sensory characteristics of Spanish dry-cured hams have been studied. Five batches of hams were manufactured using the posterior legs of pigs fed on diets with the same ingredients except for the oil source: sunflower (C), linseed (L) or linseed and olive (1/1, w/w, LO). Two different α-tocopheryl acetate concentrations [20 (C, L and LO) or 220 (LOE and LE)mg/kg diet] were used. Biceps femoris and Semitendinosus/Semimembranosus muscles from hams with low polyunsaturated fatty acid n-6/n-3 ratio (less than 3) were obtained from animals fed on linseed and linseed/olive oil enriched diets. However, hams from animals fed on diets added with linseed and α-tocopheryl acetate (20mg/kg diet) (batch L) were rejected by consumers because of less acceptable sensory characteristics and higher TBARs. The remaining hams had satisfactory sensory and nutritional characteristics.

Estudio cinético de la fotodegradación del ión p-hidroxibencenodiazonio en medio polar / Kinetic study of the photodegradation of p-hydroxybenzenediazonium ion in polar media

Se ha realizado un estudio sobre la fotodescomposición del ión p-hidroxibencenodiazonio (PDQ) basado en los datos espectrofotométricos y cromatográfi cos obtenidos con disoluciones de PDQ expuestas a irradiación UV (254 nm) en medio de acetonitrilo y agua. Los resultados de HPLC y HPLC-masa (HPLC/MS) indican que el 4-acetamidofenol es el principal producto que se forma tras la irradiación de PDQ en acetonitrilo. Esto se explica como consecuencia de la formación inicial del catión arilo, que posteriormente participa en una reacción de Ritter. El análisis cinético de los datos espectrofotométricos revela que la fotodegradación de PDQ es más rápida en acetonitrilo (constante de velocidad observada, kobs, = 0,1442 s-1) que en acetonitrilo acidifi cado (kobs = 0,009 s-1), lo que indica una mayor fotoestabilidad de la especie protonada derivada de PDQ. La constante de segundo orden (0,062 M s-1) encontrada para la fotodescomposición de PDQ en tampón fosfato (pH 7) se justifi ca por el establecimiento de un equilibrio entre las especies protonada y no protonada procedentes de la disociación ácida de PDQ

A study on the photodecomposition of p-hydroxybenzenediazonium ion (PDQ) has been made using chromatographic and spectrophotometric data obtained from UV-irradiated (254 nm) PDQ solutions in acetonitrile and aqueous media. The HPLC and HPLC-mass results indicate that 4-acetamidophenol is the main product formed after the irradiation of PDQ in acetonitrile. This is explained as a consequence of the initial formation of the aryl cation which is later involved in a Ritter’s reaction. A kinetic analysis of the spectrophotometric data reveals that PDQ photodegradation is faster in acetonitrile (observed rate constant (kobs) = 0.1442 s-1) than in acidifi ed acetonitrile (kobs = 0.009 s-1) indicating a higher photostability of the protonated species derived from PDQ. The second order constant (0.062 M s-1) found for the PDQ photodecomposition in phosphate buffer (pH 7) is explained in term of the equilibrium between protonated and non-protonated species coming from the acid dissociation of PDQ

Destruction of Salmonella Senftenberg on the shells of intact eggs by thermoultrasonication.

The combined effect of ultrasonic waves and heat treatment applied simultaneously was evaluated on the survival of strains of Salmonella Senftenberg on shells of intact eggs. This combined process has a higher killing effect than heat treatment alone. The decimal reduction times (D-values) were decreased by 65.2 to 11.1% in the temperature range studied (57.8 to 67 degrees C). In contrast to the effect on Salmonella enterica serovar Enteritidis in a previous study, thermoultrasonication had no important advantage for elimination of Salmonella Senftenberg. However, because 52 degrees C is a nonlethal temperature for Salmonella Senftenberg, the conditions used for the elimination of Salmonella Enteritidis (52 degrees C for 12 min) in the previous study would be equivalent to ultrasonic treatment alone in the present study. This thermoultrasonication treatment may result in a 100-fold greater reduction of Salmonella Senftenberg than that achieved by common in-shell egg pasteurization (60 degrees C for 3.5 min).

Effect of thermoultrasonication on Salmonella enterica serovar Enteritidis in distilled water and intact shell eggs.

The combined effects of simultaneous application of ultrasonic waves and heat treatment (thermoultrasonication) on the survival of a strain of Salmonella enterica Enteritidis was studied in both distilled water and intentionally contaminated intact eggs immersed in water. Although minor differences were observed between parameters obtained for thermoultrasonic treatment of bacteria suspended in water and those attached to the shell egg, the thermoultrasonication effects were considered to be of the same level in the range of temperatures assayed (52 to 58 degrees C). This combined process presented a clearly higher killing effect than the heat treatment alone. It decreased the decimal reduction times (D-values) by 80 to 55%, respectively, in the range of temperatures for heat treatment when the organism was suspended in water, which means a 99.5% reduction (5D to >2D) of the original bacterial load versus a 90% reduction for the heat treatment alone. The practical implications of the phenomenon are discussed.

Oxidative effects induced by dediazoniation of the p-hydroxybenzenediazonium ion in a neutral aqueous medium.

The toxicity of arenediazonium ions is believed to result from the appearance of very reactive compounds during the dediazoniation process. In the case of the p-hydroxybenzenediazonium ion (PDQ), radical species generated during dediazoniation could potentially initiate lipid peroxidation. The data obtained in spectrophotometric experiments suggest that an interaction between PDQ and linoleic acid (LA) gives rise to the characteristic absorption of oxidized products deriving from LA, both in the presence and absence of a mixed micellar medium containing the surfactant Tween 20 (Tw20). Spectroscopic evidence also clearly points to the interference of these processes in the dediazoniation of PDQ. Analysis by reverse-phase, high-pressure liquid chromatography (HPLC) confirms that the decomposition of PDQ in a mixed micellar medium induces the peroxidation of both LA and methyl linoleate (MEL), thus causing the appearance of peaks characteristic of dienic conjugated hydroperoxides. The same products are observed after interaction between LA and the water-soluble 2,2'-azobis (2-amidinopropane), a frequently used initiator of lipid peroxidation. The proportion of isomers produced during the peroxidation process agrees well with that reported for reactions mediated by free radicals. A further chromatographic analysis of the decomposition of PDQ in the presence of 2-methylcyclohexa-2,5-diene-1-carboxylic acid (CHD) shows that phenol and quinone are the main products of the reaction. These results are discussed on the understanding that aryl and peroxyl radicals abstract a hydrogen atom from CHD, in accordance with our general scheme for PDQ dediazoniation described in a previous publication.

Estudio cinético de la desdiazoación en medio acuoso del tetrafluorborato de bencenodiazonio / The kinetic study of dediazoniation in an aqueous medium of benzenediazonium tetraflourborate

Los análisis cinéticos realizados a diferentes temperaturas (20º C - 40º C) indican que el proceso de desdiazoación del ion bencenodiazonio (BZ) es de orden uno respecto a BZ siendo A = 2,3.1015 s-1 y Ea = 112,5 kJ.mol-1 en la ecuación de Arrhenius así como A H = 110,0 kJ.mol-1 y AS = 40,7 J.K-1.mol-1 para la ecuación de Eyring. Los resultados cromatográficos revelan que BZ se descompone por un proceso heterolítico mediado por el catión arilo. La presencia de sales Cu(I) o de Cu(II) y ácido ascórbico produce un cambio del mecanismo de reacción. Los compuestos intermedios originados en estas condiciones son especies estables que pueden ser transportadas en la sangre. El modelo estudiado sugiere una posible explicación para la localización descrita en la literatura para los tumores producidos por la administración de BZ a ratas (AU)

Dediazoniation of p-hydroxybenzenediazonium ion in a neutral aqueous medium.

The dediazoniation of p-hydroxybenzenediazonium ion (PDQ) in a neutral aqueous medium has been studied under controlled experimental conditions to prevent photochemical and/or heterolytic side-reactions. Oxygen increased the dediazoniation rate of PDQ and caused the appearance of quinone and hydroquinone. An accumulation of quinone deriving from the reduction of PDQ by hydroquinone was also observed. In ESR analyses with different spin traps, the most stable signal was identified as belonging to the adduct of the p-hydroxyphenyl radical, even in the presence of dimethylsulfoxide or ethanol. A general scheme is proposed including three pathways for the homolytic dediazoniation of PDQ. Pathway 1 represents dediazoniation induced by a hydroxyl ion, a slow process at neutral pH and an even slower one with deaerated samples; a favored quinoid structure is put forward to explain these results. In pathway 2, the formation of a semiquinone radical via the reaction of an aryl radical with oxygen is put forward to justify the increase in the dediazoniation rate in the presence of oxygen. In pathway 3, hydroquinone, produced by semiquinone dismutation, may act as a reducing agent.

Determination of microscopic dissociation constants of 3-hydroxy-alpha-(methylamino)methyl-benzenemethanol by a spectral deconvolution method.

Microscopic dissociation constants of 3-hydroxy-alpha-(methylamino)methyl-benzenemethanol have been calculated from the titration spectrophotomeric data (c = 3.8 x 10(-4) M. Ionic strength = 0.16; buffer system: H3BO3/KOH) by application of a spectral deconvolution method. The results found (pKa = 9.48; pKb = 9.71; pKc = 10.12 and pKd = 9.88) are in good concordance with those obtained from the conventional regression linear method (pKa = 9.45; pKb = 9.77; pKc = 10.14 and pKd = 9.81).