High Hydrostatic Pressure Treatment of Meat Products

High hydrostatic pressure (HHP) treatment has been described to improve the microbiological safety and shelf life of ready-to-eat (RTE) meat products, as a nonthermal decontamination technology in the meat industry, applied at pre- or post-packaging. The pathogen widely studied in this product is Listeria monocytogenes that reflects the concern of the food industry. In general, microorganism’s lethality during HHP treatment depends on specific intrinsic factors of the microorganism; those factors are related to food and technological factors of treatment. In addition to processing parameters, intrinsic factors of the food matrix also exert an effect on bacteria inactivation during pressure treatment. It is known that low water activity (aw) protects microorganisms against the effects of pressure. Predictive modelling is an important tool of the novel microbial food safety management strategy that provides with accurate information to demonstrate and guarantee the safety and shelf life of the food products. The chapter describes the effect of parameters on the efficiency of this technology on meat products over pathogens, composition and the sensorial quality consequences. The predictive modelling tool is introduced for the optimisation of meat treatment

Unveiling fresh-cut lettuce processing in argentine industries: evaluating Salmonella levels using predictive microbiology models

A survey was performed to gather information on the processing steps, conditions, and practices employed by industries processing ready-to-eat (RTE) leafy vegetables in Argentina. A total of seven industries participated in the survey. A cluster analysis of the data obtained was performed to identify homogeneous groups among the participating industries. The data collected were used as inputs of two predictive microbiology models to estimate Salmonella concentrations after chlorine washing, during storage and distribution of final products, and to rank the different practices according to the final estimated Salmonella levels. Six different clusters were identified by evaluating the parameters, methods, and controls applied in each processing step, evidencing a great variability among industries. The disinfectant agent applied by all participating industries was sodium hypochlorite, though concentrations and application times differed among industries from 50 to 200 ppm for 30 to 110 s. Simulations using predictive models indicated that the reductions in Salmonella in RTE leafy vegetables would vary in the range of 1.70–2.95 log CFU/g during chlorine-washing depending on chlorine concentrations applied, washing times, and vegetable cutting size, which varied from 9 to 16 cm2 among industries. Moreover, Salmonella would be able to grow in RTE leafy vegetables during storage and distribution, achieving levels of up to 2 log CFU/g, considering the storage and transportation temperatures and times reported by the industries, which vary from 4 to 14 °C and from 18 to 30 h. These results could be used to prioritize risk-based sampling programs by Food Official Control or determine more adequate process parameters to mitigate Salmonella in RTE leafy vegetables. Additionally, the information gathered in this study is useful for microbiological risk assessments

Modelling of the Behaviour of Salmonella enterica serovar Reading on Commercial Fresh-Cut Iceberg Lettuce Stored at Different Temperatures

The aim of this study was to model the growth and survival behaviour of Salmonella Reading and endogenous lactic acid bacteria on fresh pre-cut iceberg lettuce stored under modified atmosphere packaging for 10 days at different temperatures (4, 8 and 15 °C). The Baranyi and Weibull models were satisfactorily fitted to describe microbial growth and survival behaviour, respectively. Results indicated that lactic acid bacteria (LAB) could grow at all storage temperatures, while S. Reading grew only at 15 °C. Specific growth rate values (μmax) for LAB ranged between 0.080 and 0.168 h−1 corresponding to the temperatures 4 and 15 °C while for S. Reading at 15 °C, μmax = 0.056 h−1. This result was compared with published predictive microbiology models for other Salmonella serovars in leafy greens, revealing that predictions from specific models could be valid for such a temperature, provided they were developed specifically in lettuce regardless of the type of serovars inoculated. The parameter delta obtained from the Weibull model for the pathogen was found to be 16.03 and 18.81 for 4 and 8 °C, respectively, indicating that the pathogen underwent larger reduction levels at lower temperatures (2.8 log10 decrease at 4 °C). These data suggest that this Salmonella serovar is especially sensitive to low temperatures, under the assayed conditions, while showcasing that a correct refrigeration could be an effective measure to control microbial risk in commercial packaged lettuce. Finally, the microbiological data and models from this study will be useful to consider more specifically the behaviour of S. Reading during transport and storage of fresh-cut lettuce, elucidating the contribution of this serovar to the risk by Salmonella in leafy green products

Risk Factors Influencing Microbial Contamination in Food Service Centers

An improvement of food service centers in recent years has been made based on the implementation of the principles of the Hazard Analysis and Critical Control Points (HACCP) system. Food safety preventive measures have been focused on training of handlers in hygiene practices and on improving the sanitary quality of meals. In Europe, an increasing trend in foodborne outbreaks has been attributed to catering businesses. This fact highlights that the impact of preventive measures in the past few years has not been sufficiently effective as expected. Special attention should be paid to food services destined to susceptible population, such as hospitals, long-term care facilities, or school canteens, because people could be more susceptible to become ill when exposed to foodborne agents. There are numerous relevant factors influencing microbial contamination of foods, according to the preparation method, hygienic sanitary conditions of catering facilities, or food handling, storage, and distribution. In the present chapter, a review of the most significant risk factors influencing microbial contamination of foods in food service centers are described with special focus on those establishments where susceptible population (i.e., children, elderly, immunocompromised people) is present. Besides, potential preventive measures to be considered in that establishments and correct implementation of food safety actions are given to provide useful recommendations to food handlers, food operators, and risk managers

Improve and application of a new methodologic tool adapted to the European Higher Education Area applied in Degree in Food Science and Technology (CYTA), in Forest Engineering (GIFOR) and in Veterinary

La masificación en las aulas de las universidades plantea grandes retos en el desarrollo de la enseñanza según el modelo del Espacio Europeo de Enseñanza Superior (EEES). El presente trabajo desarrolló una herramienta metodológica (Píldoras Informativas) para potenciar la implicación del alumnado en el aprendizaje autónomo, basado en la creación y edición de videos por parte del alumnado, guiada, orientada y evaluada por el profesor mediante las Guías Director. Se ha llevado a cabo la introducción de las píldoras informativas en las sesiones expositivas de asignaturas de grados impartidos en la Universidad de Córdoba, incluyendo asignaturas inmersas en itinerario de inglés. Con los resultados obtenidos se plantea la creación de seminarios de difusión de la metodología para profesorado en formación.The overcrowding in the classrooms of the universities poses great challenges in the development of the teaching according to the model of the European Space of Higher Education (EHEA). The present work developed a methodological tool (Informative Pills) to enhance the involvement of students in autonomous learning, based on the creation and editing of videos by the students, guided and evaluated by the teacher through the Director Guides. The introduction of the informative pills has been carried out in the expositive sessions of subjects taught at the University of Córdoba, including subjects immersed in the English language. With the results obtained, it is proposed the creation of seminars to disseminate the methodology for teaching staff in training. Keywords: Information pills, short videos, active student participation

Modeling the Combined Effects of Temperature, pH, and Sodium Chloride and Sodium Lactate Concentrations on the Growth Rate of Lactobacillus plantarum

Nowadays, microorganisms with probiotic or antimicrobial properties are receiving major attention as alternative resources for food preservation. Lactic acid bacteria are able to synthetize compounds with antimicrobial activity against pathogenic and spoilage flora. Among them, Lactobacillus plantarum ATCC 8014 has exhibited this capacity, and further studies reveal that the microorganism is able to produce bacteriocins. An assessment of the growth of L. plantarum ATCC 8014 at different conditions becomes crucial to predict its development in foods. A response surface model of the growth rate of L. plantarum was built in this study as a function of temperature (4, 7, 10, 13, and 16°C), pH (5.5, 6.0, 6.5, 7.0, and 7.5), and sodium chloride (0, 1.5, 3.0, 4.5, and 6.0%) and sodium lactate (0, 1, 2, 3, and 4%) concentrations. All the factors were statistically significant at a confidence level of 90%  (p<0.10). When temperature and pH increased, there was a corresponding increase in the growth rate, while a negative relationship was observed between NaCl and Na-lactate concentrations and the growth parameter. A mathematical validation was carried out with additional conditions, demonstrating an excellent performance of the model. The developed model could be useful for designing foods with L. plantarum ATCC 8014 added as a probiotic

Studying and modeling of the effect of decontamination and disinfection of pathogenic microorganism in minimally processed vegetable products

La presente tesis tiene como objetivo principal cuantificar el efecto de diferentes procesos alimentarios sobre el comportamiento de las bacterias patógenas, Escherichia coli O157: H7 y Salmonella spp., en vegetales (Introducción). Por tanto, la principal contribución de esta tesis consiste en proporcionar herramientas cuantitativas basadas en modelos predictivos como apoyo a los sistemas de gestión de riesgos microbiológicos en la industria de vegetales. En primera lugar, se desarrolló un modelo matemático de contaminación cruzada de E. coli O157:H7 durante el procesamiento de vegetales IV gama que fue simulado en in-silico (Capítulo I). Tres escenarios diferentes fueron contemplados, denominados S1, S2, y S3, y que correspondieron a diferentes concentraciones iniciales en un lote contaminado a la entrada en la línea de procesos, esto es 0,01, 1 y 100 ufc / g, respectivamente. Dado los bajos niveles simulados, las diferencias entre escenarios sólo se observaron para los valores de prevalencia resultantes, y no para concentración (p <0,001). En resumen, el modelo evidenció que la contaminación cruzada fue posible en todos los escenarios probados. Dada la importancia de cuantificar el efecto de los nuevos tratamientos de desinfección utilizados para minimizar la contaminación cruzada durante la etapa de lavado, la eficacia de un tratamiento electroquímico en la desinfección del agua, usando electrodos con boro de diamante, fue estudiado junto con su idoneidad para su aplicación en la industria de productos de IV Gama (Capítulo II). Se estudio el agua del grifo (TW) y TW suplementada con NaCl (NaClW), ambas con diferentes niveles de materia orgánica (60, 300, 550 ± 50 y 750 ± 50 mg / L). El cloro libre y total, pH, potencial oxidación-reducción, COD y la temperatura fueron analizados durante los tratamientos. En condiciones óptimas se obtuvieron reducciones de 5 unidades logarítmicas de E. coli O157: H7. Los resultados proporcionan la base adecuada para desarrollar modelos predictivos que describen la reducción en función del tiempo a los diferentes niveles de materia organica. El modelo de Weibull fue el modelo que obtuvo el mejor ajuste a los datos de supervivencia. El efecto de los tratamientos de desinfección sobre el crecimiento posterior de E. coli O157: H7 en vegetales IV gama también fue estudiado considerando tratamientos tradicionales y alternativos, como el uso de cloro y agua electrolizada, respectivamente (Capítulo III y IV). En el primer caso, lechuga iceberg IV gama inoculada con E. coli O157: H7 fue sometida a lavado con agua clorada (150 mg / ml) y envasada en atmósfera modificada en un ensayo llevado acabo a escala de laboratorio/piloto. El potencial de crecimiento del patógeno fue evaluado a 4, 8, 13 y 16 °C con múltiples repeticiones. El patógeno fue capaz de crecer a temperaturas ≥ 8 °C, aunque a temperaturas bajas, los datos presentaron una gran variabilidad entre repeticiones. Para el tratamiento de agua electrolizada neutra (AEN), el diseño experimental fue el mismo al utilizado en el estudio de tratamiento con cloro. Los resultados indicaron que el crecimiento del patógeno en la lechuga tratada con AEN fue menor que la observada con agua clorada. En ambos experimentos, se propuso un modelo tipo Ratkowsky para representar la relación entre la temperatura y la tasa de crecimiento. La capacidad de supervivencia de E. coli O157: H7 y...The present thesis is aimed at quantifying the effect of different food process on fate of enteric pathogenic bacteria, Escherichia coli O157:H7 and Salmonella spp. in vegetables (Introduction). The main contribution of this thesis lies in providing quantitative tools based on predictive models to support microbial risk management systems in the Vegetable Industry. In first instance, a mathematical model describing cross contamination of E. coli O157:H7 during processing of fresh-cut vegetable was developed and simulated in silico (Chapter I ). Three different scenarios, named S1, S2, and S3, were considered to represent the initial concentration on the contaminated batch entering the processing line which corresponded to 0.01, 1 and 100 cfu/g, respectively. Given the low initial levels, differences between scenarios were only observed in prevalence and not in concentration (p< 0.001). The model evidenced that cross contamination was possible in all simulated scenarios. Given the importance of quantifying the effect of new disinfection treatments as means of avoiding cross contamination during washing step, the efficacy of an electrochemical treatment in water disinfection, using boron-doped diamond electrodes, was studied together with its suitability for the fresh-cut produce industry (Chapter II). Tap water (TW), and TW supplemented with NaCl (NaClW) containing different levels of organic matter around 60, 300, 550±50 and 750±50 mg/L; combined and total chlorine, pH, oxidation-reduction potential, COD and temperature were monitored during the treatments and obtained in this optimum conditions reductions of 5 log units of E. coli O157:H7. Results provided suitable base to develop predictive models describing reduction as a function of time at the different studied conditions, the Weibull model obtaining a good performance. The effect of disinfection treatment on subsequent growth of E. coli O157:H7 in fresh-cut leafy vegetables was studied considering traditional and alternative treatments, based on chlorine and electrolyzed water, respectively (Chapter III and IV). In the first case, fresh-cut iceberg lettuce inoculated with E. coli O157:H7 was submitted to chlorine washing (150 mg/mL) and modified atmosphere packaging on laboratory/pilot scale. Potential growth of the pathogen was..

PUESTA A PUNTO Y APLICACIÓN DE UNA NUEVA HERRAMIENTA METODOLÓGICA ADAPTADA AL ESPACIO EUROPEO DE ENSEÑANZA SUPERIOR: PÍLDORAS INFORMATIVAS APLICADAS EN LOS GRADOS DE CIENCIA Y TECNOLOGÍA DE LOS ALIMENTOS (CYTA), INGENIERÍA FORESTAL (GIFOR) Y VETERINARIA

The overcrowding in the classrooms of the universities poses great challenges in the development of the teaching according to the model of the European Space of Higher Education (EHEA). The present work developed a methodological tool (Informative Pills) to enhance the involvement of students in autonomous learning, based on the creation and editing of videos by the students, guided and evaluated by the teacher through the Director Guides. The introduction of the informative pills has been carried out in the expositive sessions of subjects taught at the University of Córdoba, including subjects immersed in the English language. With the results obtained, it is proposed the creation of seminars to disseminate the methodology for teaching staff in training. Keywords: Information pills, short videos, active student participation.La masificación en las aulas de las universidades plantea grandes retos en el desarrollo de la enseñanza según el modelo del Espacio Europeo de Enseñanza Superior (EEES). El presente trabajo desarrolló una herramienta metodológica (Píldoras Informativas) para potenciar la implicación del alumnado en el aprendizaje autónomo, basado en la creación y edición de videos por parte del alumnado, guiada, orientada y evaluada por el profesor mediante las Guías Director. Se ha llevado a cabo la introducción de las píldoras informativas en las sesiones expositivas de asignaturas de grados impartidos en la Universidad de Córdoba, incluyendo asignaturas inmersas en itinerario de inglés. Con los resultados obtenidos se plantea la creación de seminarios de difusión de la metodología para profesorado en formación

Assessing Listeria monocytogenes growth during Spanish-style green table olive fermentation

3 Tablas.-- 3 FigurasTable olives are one of the most important fermented vegetables in the Mediterranean countries. Although this fermented vegetable has a long record of microbial safety, various studies have shown the presence of Listeria monocytogenes during table olive processing. This study focused on evaluating the behaviour of a cocktail of L. monocytogenes strains during fermentation of Spanish-style green Manzanilla olives. For this purpose, a challenge test consisting of artificial inoculation of olive fermentation with high levels of the food-borne pathogen (7.0 log10 CFU/ml) was performed. The fermentation was carried out at the laboratory scale in sealed glass bottles (n = 168) under controlled conditions to avoid the initiation of lactic acid fermentation intentionally. This point was confirmed by the evolution of pH, which ranged from an initial 9.0 to final 6.0 units (decrease kinetic constant of −0.0016 h−1), as well as by the behaviour of lactic acid and mesophilic bacteria during the study (55 days). The fate of L. monocytogenes during fermentation was described using mathematical models, including the two-term Gompertz equation. During this time, the food-borne pathogen showed an initial growth phase which lasted until 250 h, reaching a maximum population level close to 9.0 log10 CFU/ml, even in the presence of high salt concentrations (>6.0% NaCl). Then, a rapid decline phase was observed but continuously detecting a residual tail of around 2 log10 CFU/ml. Data obtained in this work shows the importance of the control of olive fermentation, especially during the first weeks when pH is alkaline-neutral and environmental conditions could favour L. monocytogenes growth.This research was funded through TOBE project (RTI2018-100883-B-I00, MCIU/AEI/FEDER, UE), Council of Economy, Knowledge, Business and University of Junta de Andalucía (Project AT 2017–5686), and FEDER European funds.Peer reviewe