Radiofrequency Inactivation of Salmonella in Black Pepper and Dried Basil Leaves Using In-package Steaming.

Radiofrequency (RF) heating has been extensively studied for pasteurizing low-moisture foods. Currently, bulk foods are treated with radiofrequency; potential cross-contamination may occur during packaging of pasteurized products. As an alternative, in-package RF processing was evaluated for Salmonella inactivation on black peppercorns and dried basil leaves and prevention of cross-contamination during storage postprocessing. In-package steaming refers to the process in which the samples were heated in a steam vent package to generate and retain steam during the treatment. This treatment achieved good heating uniformity which could be because of the circulation of steam within the package. One-way steam vent allowed the release of excess steam once a threshold pressure was achieved and later returned to its original position to seal the package, when the RF energy was removed. In-package RF steaming of black peppercorns and dried basil leaves for 135 s and 40 s, respectively, resulted in more than 5 log reduction of Salmonella. The steam vent remained stable posttreatment and properly sealed the package to protect the product from any external contamination. These results indicate that the use of steam vent could effectively pasteurize black peppercorns and dried basil leaves could be beneficial in preventing the potential cross-contamination postprocessing.

Postharvest heat treatments to inhibit Penicillium digitatum growth and maintain quality of Mandarin (Citrus reticulata blanco).

Use of fungicides is a common practice as a postharvest treatment to control fruit decay. Nowadays, environment friendly technologies, such as heat treatments, are viable replacements. This study evaluated the effects of post-harvest heat treatments (traditional and microwave-assisted) on mandarins intentionally inoculated with Penicillium digitatum. For the studied heat treatments, the target temperature was 50 °C, which was held for 2.5 min. After heating, mandarins were cooled and stored at 25 °C for 13 days. MW treatments effectively prevented mold growth during storage, while HW only delayed it. Control mandarins (without treatment) showed the highest significant weight loss. Neither thermal treatment nor storage affected fruit juice pH (p > 0.05). Treated mandarins had a significantly lower vitamin C content than control fruits throughout storage, and all mandarins lost firmness by the 13th day (p < 0.05). Control and MW-treated mandarins had lower citric acid content; however, they retained color, total soluble solids (TSS) and had a higher maturity index. While HW mandarins did not have changes in citric acid content, they had higher TSS, and lower maturity index. MW-assisted treatments were effective at inactivating molds and helped retain some nutritional and physical-chemical characteristics of mandarins. However, juice of MW-treated mandarins was not preferred by judges in the sensory tests, the juice was rated lower than that obtained from the other treatment. Postharvest heat treatments may constitute a helpful application to control mandarin' fungal decay.

Enterococcus faecium as a Salmonella surrogate in the thermal processing of wheat flour: Influence of water activity at high temperatures.

This study investigated the influence of temperature-dependent water activity (aw) on thermal resistances of Enterococcus faecium NRRL B-2354 (E. faecium) and Salmonella Enteritidis PT 30 (S. Enteritidis) in wheat flour. The aw for wheat flour samples at 20, 40, and 60 °C was determined by a vapor sorption analyzer and at 75, 80 and 85 °C using custom-built thermal cells with high temperature humidity sensors. Full-factorial isothermal inactivation studies of both strains in sealed aluminum-test-cells included three temperatures (75, 80, and 85 °C) and three aw,25°C levels (0.30, 0.45 and 0.60 within ±0.02 range, prior to the thermal treatments). Isotherm results of wheat flour demonstrate a significant increase (P < 0.05) of aw as temperature rises (e.g. aw,25°C = 0.45 ±â€¯0.02 became aw,80°C = 0.71 ±â€¯0.02 in a closed system). Inactivation kinetics of both microorganisms fitted a log-linear model, the yielded D-values varied from 2.7 ±â€¯0.2 min (D85°C of S. Enteritidis at aw,25°C 0.60 ±â€¯0.02) to 65.8 ±â€¯2.5 min (D75°C of E. faecium at aw,25°C 0.30 ±â€¯0.02). The zT of E. faecium and S. Enteritidis decreased from 16.4 and 16.9 °C, respectively, to 10.2 °C with increased moisture content (dry basis) from 10 to 14%. Under all tested conditions, E. faecium exhibited equal or higher (1.0-3.1 times) D- and zT-values than those of Salmonella. Overall, E. faecium should be a conservative surrogate for Salmonella in thermal processing of wheat flour for control of Salmonella over a moisture content of 10-14% and treatment temperatures between 75 and 85 °C.

Effects of Inoculation Procedures on Variability and Repeatability of Salmonella Thermal Resistance in Wheat Flour.

Limited prior research has shown that inoculation methods affect thermal resistance of Salmonella in low-moisture foods; however, these effects and their repeatability have not been systematically quantified. Consequently, method variability across studies limits utility of individual data sets and cross-study comparisons. Therefore, the objective was to evaluate the effects of inoculation methodologies on stability and thermal resistance of Salmonella in a low-moisture food (wheat flour), and the repeatability of those results, based on data generated by two independent laboratories. The experimental design consisted of a cross-laboratory comparison, both conducting isothermal Salmonella inactivation studies in wheat flour (~0.45 water activity, 80°C), utilizing five different inoculation methods: (i) broth-based liquid inoculum, (ii) lawn-based liquid inoculum, (iii) lawn-based pelletized inoculum, (iv) direct harvest of lawn culture with wheat flour, and (v) fomite transfer of a lawn culture. Inoculated wheat flour was equilibrated ~5 days to ~0.45 water activity and then was subjected to isothermal treatment (80°C) in aluminum test cells. Results indicated that inoculation method impacted repeatability, population stability, and inactivation kinetics (α = 0.05), regardless of laboratory. Salmonella inoculated with the broth-based liquid inoculum method and the fomite transfer of a lawn culture method exhibited instability during equilibration. Lawn-based cultures resulted in stable populations prior to thermal treatment; however, the method using direct harvest of lawn culture with wheat flour yielded different D-values across the laboratories (α = 0.05), which was attributed to larger potential impact of operator variability. The lawn-based liquid inoculum and the lawn-based pelletized inoculum methods yielded stable inoculation levels and repeatable D-values (~250 and ~285 s, respectively). Also, inoculation level (3 to 8 log CFU/g) did not affect D-values (using the lawn-based liquid inoculum method). Overall, the results demonstrate that inoculation methods significantly affect Salmonella population kinetics and subsequent interpretation of thermal inactivation data for low-moisture foods.

Influence of Water Activity on Thermal Resistance of Microorganisms in Low-Moisture Foods: A Review.

A number of recent outbreaks related to pathogens in low-moisture foods have created urgency for studies to understand the possible causes and identify potential treatments to improve low-moisture food safety. Thermal processing holds the potential to eliminate pathogens such as Salmonella in low-moisture foods. Water activity (aw ) has been recognized as one of the primary factors influencing the thermal resistance of pathogens in low-moisture foods. But most of the reported studies relate thermal resistance of pathogens to aw of low-moisture foods at room temperature. Water activity is a thermodynamic property that varies significantly with temperature and the direction of variation is dependent on the product component. Accurate methods to determine aw at elevated temperatures are needed in related research activities and industrial operations. Adequate design of commercial thermal treatments to control target pathogens in low-moisture products requires knowledge on how aw values change in different foods at elevated temperatures. This paper presents an overview of the factors influencing the thermal resistance of pathogens in low-moisture foods. This review focuses on understanding the influence of water activity and its variation at thermal processing temperature on thermal resistance of pathogens in different low-moisture matrices. It also discusses the research needs to relate thermal resistance of foodborne pathogens to aw value in those foods at elevated temperatures.

Thermal inactivation of Salmonella enteritidis PT 30 in almond kernels as influenced by water activity.

Salmonellosis outbreaks related to consumption of raw almonds have encouraged the scientific community to study the inactivation kinetics of pathogens in this dry commodity. However, the low moisture content of the product presents a challenge for thermal control, because the time required to achieve the desired thermal inactivation of microorganisms increases sharply with reduced moisture content and water activity. In this study, we explored and modeled the heat inactivation of Salmonella enterica serovar Enteritidis PT 30 in almond cultivar 'Nonpareil' kernel flour at four water activity (a(w)) values (0.601, 0.720, 0.888, and 0.946) using four temperatures for each a(w). The results showed that the inactivation was well fitted by both Weibull distribution (R(2) = 0.93 to 1.00) and first-order kinetics (R(2) = 0.82 to 0.96). At higher a(w) values, the rate of inactivation increased and less time was needed to achieve the required population reduction. These results suggest that, to avoid deterioration of product quality, shorter process times at lower temperatures may be used to achieve desired inactivation levels of Salmonella Enteritidis PT 30 by simply increasing the moisture content of almonds. These goals could be achieved with the use of existing procedures already practiced by the food industry, such as washing or prewetting scalding before heat inactivation.

Hot water bath treatments assisted by microwave energy to delay postharvest ripening and decay in strawberries (Fragaria × ananassa).

BACKGROUND: A lab-scale approach using microwave (MW)-assisted hot water treatments was developed and tested to assess the potential of this heating method to delay postharvest ripening and decay in strawberries. Strawberries (Fragaria × ananassa) immersed in water were exposed to microwaves at a frequency of 2450 MHz for 3 min at 514 W or 1 min 50 s at 763 W to reach an average temperature of 43.8 ± 0.6 °C at the fruit centre. Another batch was treated in hot water at 45 °C for 15 min, and a final batch was not treated (control). RESULTS: After 9 days of refrigerated storage (3 °C and 90% relative humidity), all heat-treated strawberries showed significant retention of quality parameters such as colour and firmness and significantly lower yeast and mould populations (P < 0.05). CONCLUSION: Strawberries subjected to MW-assisted hot water treatments showed significantly better retention of lightness compared with conventionally treated berries. A short (1 min 50 s) treatment at 763 W was the best choice to prevent strawberry decay.

Estado actual de la radioterapia en Venezuela / Actual state of the radiotherapy in Venezuela

Este trabajo se realiza como una actualización de otro anteriormente hecho por la Cátedra de Radioterapia y Medicina Nuclear de la Universidad Central de Venezuela de 1986. Con este fin se visitaron 18 centros públicos de radioterapia, obteniéndose información sobre ambiente físico, unidades de tratamiento, braquiterapia, personal médico y paramédico, registro de dator clínicos de pacientes. Resultado: solo 4 de 7 unidades de altovoltaje funcionan; existen 20 unidades de Co60, de las cuales 17 funcionan y únicamente 2 lo hacen en forma adecuada. De los 7 aceleradores lineales y 7 simuladores existentes, únicamente funcionan 5 de cada uno. Unicamente 3 centros hacen dosimetría por computación el resto lo hace en forma manual. En el 50 por ciento de los servicios de radioterapia, los equipos de braquiterapia intracavitaria se encuentran en condiciones precarias. Dos hospitales poseen equipos de braquiterapia a control remoto. Existe un déficit importante de técnicas en radioterapia, físicos en radiaciones y dosimetristas. en conclusión la radioterapia en Venezuela confronta serios problemas debido a la falta de recursos materiales y humanos. Recomendamos la sustitución de equipos con DFP menor de 80 cm., el cambio de las fuentes de Co60 con rendimientos menores de 100 cGy/min., el remplazo de las fuentes y de los equipos de radioterapia intracavitaria, la dotación de simuladores, entrenamiento de personal técnico y formación de físicos y dosimetristas

Encuesta sobre tabaquismo a estudiantes de tercer año de medicina de la Universidad Nacional de Cordoba / Survey about smoking of students of the third year of medicine of Universidad Nacional de Cordoba

De una encuesta sobre tabaquismo contestada por 364 (70%) de 520 alumnos de la 2¬ Cátedra de Patología de la Universidad Nacional de Córdoba resaltan los siguientes datos: El 23% de los alumnos fuman (29% de los varones y 17% de las mujeres). Esta generación de jóvenes fuma mucho menos que sus progenitores (70% de los padres y 25% de las madres fuman). A pesar de la buena información existente aún son expuestos al humo del cigarrillo niños y embarazadas en un porcentaje significativo. A los fumadores les resulta difícil dejar el hábito. La mayoría lo intentó infructuosamente. Al 80% de los alumnos les causa desagrado que se fume en ambientes cerrados. La mayoría de los estudiantes fumadores declara respetar el derecho de los no-fumadores. Pocas cátedras de nuestras materias básicas se ocupan del tema, y en varias, docentes fuman y/o permiten fumar quebrantando normas específicas de nuestra Facultad y Universidad, actitudes que desaprueba la mayoría de los alumnos y lo conceptúar, un mal ejemplo y un hecho contradictorio. Exhortamos a los fumadores a respetar los derechos de los no-fumadores y a cumplir las normas sobre tabaquismo de nuestra Facultad y de nuestra Universidad. La Resolución 103/89 pide a profesores, docentes y empleados administrativos, educar con el ejemplo. ¿No es ésta una de las maneras de demostrar nuestro amor por la Universidad (AU)

Encuesta sobre tabaquismo a estudiantes de tercer año de medicina de la Universidad Nacional de Cordoba / Survey about smoking of students of the third year of medicine of Universidad Nacional de Cordoba

De una encuesta sobre tabaquismo contestada por 364 (70%) de 520 alumnos de la 2ª Cátedra de Patología de la Universidad Nacional de Córdoba resaltan los siguientes datos: El 23% de los alumnos fuman (29% de los varones y 17% de las mujeres). Esta generación de jóvenes fuma mucho menos que sus progenitores (70% de los padres y 25% de las madres fuman). A pesar de la buena información existente aún son expuestos al humo del cigarrillo niños y embarazadas en un porcentaje significativo. A los fumadores les resulta difícil dejar el hábito. La mayoría lo intentó infructuosamente. Al 80% de los alumnos les causa desagrado que se fume en ambientes cerrados. La mayoría de los estudiantes fumadores declara respetar el derecho de los no-fumadores. Pocas cátedras de nuestras materias básicas se ocupan del tema, y en varias, docentes fuman y/o permiten fumar quebrantando normas específicas de nuestra Facultad y Universidad, actitudes que desaprueba la mayoría de los alumnos y lo conceptúar, un mal ejemplo y un hecho contradictorio. Exhortamos a los fumadores a respetar los derechos de los no-fumadores y a cumplir las normas sobre tabaquismo de nuestra Facultad y de nuestra Universidad. La Resolución 103/89 pide a profesores, docentes y empleados administrativos, educar con el ejemplo. ¿No es ésta una de las maneras de demostrar nuestro amor por la Universidad