A complex multi-vector processed beef value stream was biomapped and work-in-process (WIP) was sampled at various processing points that affected the product microbiome. Coliform Petrifilm™ was used to analyze samples qualitatively and quantitatively across the meat and glaze vectors. There was an impact (p≤0.05) of the glaze distribution system on coliforms. The pumps of the glaze system were fully disassembled and additional microbial data were obtained through swabbing. WIP and sponge samples were subjected to 16S V1/V2 gene amplification with primers designed for taxonomic identification. Sequencing was conducted on the Illumina MiSeq platform and bioinformatics were developed in QIIME 2 workflows. Bespoke sample groupings were created to compare process steps, with alpha and beta diversity measures analyzed using multivariate statistical models to assess microbial community dynamics. The pumps were found to harbor a diverse and distinct microbiota, acting as reservoirs for fermentative bacteria due to biofilm formation facilitated by carbohydrates in the glaze. The distinct microbial communities found in these pumps, especially one of the three systems, revealed the need for specialized sanitation. A novel weekly deep-clean process was developed and deployed to the glaze pumps utilizing guided disassembly and manual scrubbing, gaseous chlorine dioxide, and a quaternary ammonium hydrogen peroxide biofilm stripper. The implementation of this protocol led to a reduction in coliform presence (p≤0.05), with detection rates dropping from 1.14% to 0.08% in the product and from 32.82% to 0.63% in the glaze. To provide ongoing assessment of the value stream, a unique Environmental Monitoring Program (EMP) was developed to monitor WIP samples collected routinely. After enumeration on EC Petrifilm™, colonies were isolated and subjected to automated biochemical and MALDI-TOF identification. Results showed wide agreement (85.2%) between the two systems with discrepancies resolved by nanopore WGS. The EMP revealed a coliform microbiome with few similarities to the meat and glaze samples analyzed by 16S prior to the sanitation intervention. Isolates confirmed frequent identification of non-lactose fermenting organisms on EC Petrifilm™, illustrating the vulnerability of the method to break-through growth earlier than previously documented.

The fresh-cut produce industry has seen expansive growth in recent years, to meet consumer demand ready-to-eat (RTE) salads have included the use of non-traditional ingredients. Uncommon ingredients include beet greens, kale, broccoli stalk, and Brussels sprouts, since these ingredients have not historically been consumed raw, potential food safety issues should be reassessed. Current processing technologies include produce washes that can reduce microbial levels but do not eradicate all populations. The lack of a kill step in produce processing emphasizes the need to minimize pathogen contamination during production and growth during a product’s shelf life. Listeria monocytogenes, a leading cause of foodborne illness related deaths, continues to challenge the industry with recent outbreaks and recalls of fresh-cut produce. These events present the need to better understand L. monocytogenes growth potential in RTE produce during storage and distribution. Traditional salad greens have been researched extensively, however, limited knowledge is available on new inclusions. While temperature is known to strongly influence microbial growth, the effects of physical abuse during storage and distribution are unknown. The purpose of this study was to characterize L. innocua’s, a surrogate for L. monocytogenes, growth behavior in processed beet greens, kale, broccoli stalk, and Brussels sprouts when exposed to simulated physical and thermal abuses during storage and distribution. To evaluate L. innocua growth during storage and distribution produce samples were obtained from a local processor in retail packaging and surface inoculated. The samples were conditioned at 4℃ for 18h prior to being exposed to a series of physical abuses (compression, drop, and vibration) typical of storage and distribution. After abuse, produce was incubated at 4 or 8°C and sampled post-abuse through 16 and 11 days, respectively. Samples were enumerated for L. innocua, aerobic and psychrotrophic microorganisms, and lactic acid bacteria. To monitor growing conditions in each vegetable, product pH, water activity, and headspace (gas analysis), were observed at each time pull. The study found physical abuse had no significant effect on L. innocua, or microbiota growth regardless of vegetable or incubation temperature (P > 0.05). Vegetable intrinsic factors (pH, Aw, and headspace) did not seem to interfere in L. innocua or background microbiota growth during incubation. All vegetables supported L. innocua growth under 8℃. Growth of L. innocua was greatest in beet greens, followed by kale, broccoli stalk, and Brussels sprouts in descending order. Significant growth of L. innocua at 4 and 8ᵒC was seen on day 6 and 4 in beet greens, 11 and 6 in Brussels sprouts, 16 and 4 in kale, and 16 and 6 in broccoli stalk (P < 0.05). Overall, these results show the studied RTE vegetables can support L. monocytogenes growth during storage and distribution, especially under abusive temperatures, demonstrating the importance of prevention strategies during processing and refrigeration throughout RTE produce shelf life.

No description available.

Master of Science / Food Science / Kelly J.K. Getty / Listeria monocytogenes has the potential to contaminate ready-to-eat (RTE) meat and poultry products. Listeria monocytogenes contamination is a hazard that can potentially occur after post-lethality treatment in a processing environment during slicing or packaging of RTE meat products. United States Department of Agriculture’s Food Safety and Inspection Service (USDA/FSIS) requires facilities to have intervention strategies to demonstrate control of this pathogen in RTE meat and poultry products. FSIS categorizes different intervention strategies into Alternative 1, 2, or 3. If an establishment chooses Alternative 1, it must use a post-lethality treatment that reduces or eliminates microorganisms on the product and an antimicrobial agent or process that suppresses or limits the growth of L. monocytogenes. If an establishment chooses Alternative 2, it can either use a post-lethality treatment or an antimicrobial agent or process that suppresses or limits growth of L. monocytogenes. Under Alternative 3, the establishment must have a detailed sanitation program as its intervention strategy. As establishments increase the number of interventions or change from Alternative 3 to 2 to 1, the frequency of FSIS sampling of RTE meat and poultry products for safety and wholesomeness decreases. The effectiveness of post-package decontamination technologies such as high-pressure processing, ultraviolet C light, and pre/post-package surface pasteurization have been researched for controlling L. monocytogenes in RTE products. Formulating meat products with antimicrobial additives such as lactates, sodium lactate and sodium diacetate, potassium lactate and sodium diacetate, sodium levulinate, lauric arginate, glucono-delta-lactone, or organic acids is another common approach to control L. monocytogenes in RTE meat products. Also, a combination of sodium lactate and sodium diacetate in a formulation is an acceptable antimicrobial strategy to provide Alternative 2 status. Bacteriocins such as nisin can also be added to the formulation of RTE meat and poultry products for controlling L. monocytogenes. In addition nisin can be applied as packaging film coating. Another approach for controlling L. monocytogenes in products such as jerky, kippered steaks, snack sticks and turkey tenders is the use of packaging environments and holding times prior to shipping. In conclusion, there are various approaches for controlling L. monocytogenes in RTE meat and poultry products post-lethality and processors should consider these options rather than relying on sanitation alone.

En general, el control de procesos es muy eficiente cuando el punto de operación deseado ha sido determinado a priori y el sistema tiene capacidad suficiente para responder a las perturbaciones. Mientras el control de procesos es requerido a fin de regular algunas variables de proceso, la aplicación de tal técnica puede no ser apropiada para todas las variables significativas. En algunos casos, el punto optimo de operación cambia debido al efecto combinado de perturbaciones internas y externas por lo que un sistema de control prefijado puede no responder adecuadamente a los cambios. Cuando ciertas condiciones son satisfechas, la optimización en-línea surge como una alternativa adecuada para ajustarse a ese optimo cambiante.A fin de "perseguir" este optimo móvil, la optimización en-línea resuelve en forma periódica problemas de optimización, usando datos que vienen directamente de la planta y un modelo el cual es actualizado continuamente. La aplicación mas frecuente de la optimización en-línea corresponde a la categoría de procesos continuos. Esto se debe principalmente a que los modelos de estado estacionario son mas simples y fáciles de desarrollar y validar, además de que los procesos continuos tienen normalmente asociado elevada producción y por ende, pequeñas mejoras en la eficiencia del proceso se traducen en importantes ganancias. Sin embargo, aunque el uso de modelos al estado estacionario simplifica enormemente las tareas de modelización, hace emerger ciertos aspectos ligados a la validez de la hipótesis de un estado estacionario.Comenzaron a surgir varias aplicaciones a gran escala de la optimización en-línea, pero, si bien varios vendedores ofrecen productos y servicios en este área, la mayoría de las aplicaciones industriales abordan problemas de control avanzado, dejando a la optimización en un segundo plano. Los industriales han reportado que después de cuatro décadas ha tenido lugar una mejora progresiva en la metodología llevada a cabo en la optimización en-línea, pero que siguen estando presente los puntos débiles originales. Tales aspectos están directamente relacionados con la detección del estado estacionario (o las frecuencias de las perturbaciones) y la optimización en si misma.Los objetivos de la presente tesis están dirigidos a solventar parcialmente tales puntos débiles de la metodología actual. Como resultado, se propone una estrategia alternativa que saca ventaja de las mediciones y busca una mejora continua en lugar de una optimización formal. Se muestra que tal estrategia resulta muy efectiva y puede no solo ser aplicada para la optimización de puntos de consigna, pero también para tomar (en-línea) las decisiones discretas necesarias en procesos que presentan degradación (aspecto normalmente resuelto usando programación matemática).La estructura de la tesis es como sigue. El primer capitulo explica las principales motivaciones y objetivos del trabajo, mientras que el capitulo 2 consiste en una revisión bibliográfica que abarca, hasta cierto punto, los tópicos y funcionalidades mas importantes asociados a la optimización en-línea. Luego, los capítulos 3 y 4 presentan la estrategia propuesta a través de dos metodologías para la optimización en-línea, lo cual es la contribución mas importante de la tesis. El primero, (capitulo 3) se centra en la persecución de un optimo que se mueve por el efecto combinado de perturbaciones externas e internas. Por otro lado, en el capitulo 4 se explica una metodología paralela, concebida para procesos que presentan desempeño decreciente con el tiempo y requieren decisiones discretas en relación a acciones de mantenimiento. Ambos capítulos incluyen una primera parte, mas bien teórica, y una segunda parte dedicada a la validación usando casos de referencia. Luego, el capitulo 5 describe la aplicación de tales metodología sobre dos escenarios industriales, con la intención de complementar los resultados obtenidos sobre los casos académicos. Posteriormente, el capitulo 6 aborda dos problemas asociados a la implementación: la influencia de los parámetros ajustables y la arquitectura del software usada. Finalmente, el capitulo 7 resume las principales conclusiones y observaciones de la tesis. / In general, process control is very effective when the desired operation point has been determined from prior analysis and the control system has sufficient time to respond to disturbances. While process control is required for regulating some process variables, the application of these methods may be not appropriate for all important variables. In some situations, the best operating conditions change because of the combined effect of internal and external disturbances, and a fixed control design may not respond properly to these changes. When certain conditions are met, on-line optimisation becomes a suitable choice for tracking the moving optimum.In order to "pursue" that moving optimum, on-line optimisation solves periodically optimisation problems using data coming directly form the plant and a continuously updated model. The most common use of on-line optimisation corresponds to the continuous processes category. This is mainly owed to that steady state models are simpler and easier to develop and validate, besides that continuous processes have commonly high production rates, thus small relative improvements in the process efficiency originates significant economic earnings. Nevertheless, although the use of steady state models greatly simplifies the modelling task, it raises other issues associated with the validity of the steady state assumption. Large-scale applications of on-line optimisation started to spread, however, even when several vendors offer products and services in the area, most of the application address advanced control issues while on-line optimisation is released to a second plane. Industry practitioners have reported that after four decades there has been a progressive improvement in the on-line optimisation methodology, but the same initial weakness or more generally speaking some common causes of poor performance still remain. These issues are directly related with the steady state detection (or disturbance frequency) and the optimisation itself.The objectives of this thesis work are then directed to overcome at least partially the weak points of the current approach. The result is the proposal of an alternative strategy that takes fully advantage of the on-line measurements and looks for periodical improvement rather than a formal optimisation. It is shown how the proposed approach results very efficient and can be applied not only for set-point on-line optimisation but also for taking the on-line decision required in processes that presents decaying performance (aspect typically solved of-line via mathematical programming). The thesis is structured as follows. The first chapter explains the main motivations and objectives of the work, while chapter 2 consists in a literature review that addresses, to some extension, the most significant issues around the on-line optimisation functionality. After that, chapter 3 and chapter 4 introduce two methodologies that use the proposed strategy for on-line optimisation, which is the main thesis contribution. The first one (in chapter 3) focuses in tracking fast moving optima, which is caused mainly by the combined effect of external and internal disturbances. On the other hand, a parallel methodology is explained in 4, conceived for processes that present decaying performance and that require discrete decision related to maintenance actions. Both chapters include a first part, rather theoretical, and a second part devoted to the validation over typical benchmarks. Then, chapter 5 describes the application of such methodologies over two existing industrial scenarios, in order to complement the results obtained using the benchmarks. After that, chapter 6 addresses two issues related to the implementation aspects: the influence of the adjustable parameters of the proposed procedure and the software architectures used. Finally, chapter 7 draws conclusions and main observations.

Le « corridor méditerranéen » est à la rencontre d'un projet ferroviaire espagnol datant des années 1920 et d'un projet inscrit dans la planification des réseaux transeuropéens de transport depuis les années 1990. La thèse s'intéresse à l'axe littoral qu'il désigne, comprenant des villes, des activités et un ensemble d'infrastructures. Elle part du constat que le corridor méditerranéen doit être inscrit dans un contexte territorial multiple. Il est pérenne par son inscription dans le temps long de la construction et de l'aménagement du territoire espagnol, mais changeant dans la temporalité politique de la planification et de ses phases successives. Enfin, il est multiscalaire par son inscription dans le jeu institutionnel et ses impacts territoriaux. Nous faisons l'hypothèse qu'en Espagne, le corridor méditerranéen interagit avec les enjeux politiques et économiques, au point qu'il ne peut être considéré comme un simple projet de transport (pour l'heure non matérialisé par une infrastructure), mais doit être envisagé dans sa dimension politique. À la croisée de ces enjeux, la thèse prend le parti d'une approche territoriale – à la différence de la majorité des travaux – qui permet d'aborder le corridor méditerranéen sous l'angle de son inscription dans l'espace, en prenant en compte aussi bien les problèmes économiques et politiques qui façonnent le territoire du corridor en amont que les implications du projet sur ce territoire à toutes les échelles en aval. La thèse pose deux questions centrales. Il s'agit d'abord de comprendre comment un objet, au départ un projet d'infrastructures inscrit dans un processus de prise de décision en matière d'aménagement du territoire, devient un facteur puissant de recomposition des jeux d'acteurs et de réinterprétation des paradigmes de l'aménagement des territoires à toutes les échelles. Il s'agit ensuite d'interroger la dialectique entre les différents échelons institutionnels d'une part et entre les différentes échelles territoriales (européenne, nationale, régionale et locale) d'autre part. L'inscription du projet dans les territoires peut se faire à travers différentes formes de territorialisation, matérielles ou immatérielles, de la construction d'équipements ferroviaires à la modification du jeu des acteurs dans un territoire donné autour du projet de corridor. On assiste à un double processus de politisation des intérêts locaux par l'action des associations d'entreprises au niveau régional, et de dépolitisation du débat sur le corridor par le biais de l'européanisation du projet. En s'appuyant sur un ensemble de méthodes fondées principalement sur la pratique d'entretiens, ainsi que sur l'étude des documents de planification et des manifestations du corridor méditerranéen dans le débat public, cette thèse a permis de faire émerger trois résultats principaux. Premièrement, par sa plasticité, le corridor méditerranéen devient un objet politique : il désigne à la fois un projet d'infrastructures aux caractéristiques mouvantes et un catalyseur d'intérêts de nature différente autour d'un objectif commun. Deuxièmement, le corridor méditerranéen, parce qu'il correspond à des représentations territoriales et à des objectifs différents, ne peut s'incarner comme infrastructure car sa matérialité lui ôterait son statut de fédérateur d'intérêts et détruirait l'unité fragile créée autour de sa revendication. Cette impossibilité du corridor méditerranéen est ce qui en fait un excellent médiateur entre les différents acteurs. Troisièmement, le corridor méditerranéen est au centre d'un processus multiple de territorialisation, répondant aux trois sens de ce terme : il apparaît comme un avatar, parmi d'autres, des grandes structures spatiales européennes et espagnoles ; il est un facteur d'émergence de structures territoriales nouvelles par ses impacts sur les territoires locaux ; il permet la recomposition du jeu des acteurs autour d'un projet, dans une réalité spatiale qui lui est propre / The Mediterranean corridor stands at the meeting point of a Spanish railway project in the 1920s and a second project which has formed part of the Trans-European Networks of Transport since the 1990s. The subject is thus this coastal axis, including cities, activities and infrastructure. The bottom line is the idea that the Mediterranean corridor has to be placed in a territorial context that is plural. Indeed, it is both perennial, within the scope of the long-term timeline of the construction and planning of the Spanish territory, and evolving within the political temporality of the planning process and its successive stages. It also has an inherent multiscalar component due to the institutional process and to its impact on the territory. Our hypothesis is that in Spain the corridor involves an interaction with the political and economic questions, so that it cannot be simply considered as a transport project (yet not materialized by infrastructure), and should rather be tackled through its political dimension. Right at the meeting point of these stakes, we have chosen to use a territorial approach, contrary to the majority of works that have been dedicated to this subject. This territorial angle makes it possible to study the Mediterranean corridor through its spatial dimension, taking into account both the economic and political questions that shape the corridor in its territorial aspect and the various implications of the project on this territory at all scales. This thesis develops two main ideas. The first ambition of this work is to understand how this project, which began as a plan for infrastructure as part of a decision-making process regarding spatial planning, then became a powerful factor in the rearticulation of the roles of the different stakeholders and the reinterpretation of the paradigms of planning at all scales. We will then be able to investigate the dialectics between the various institutional levels on the one hand and between the various territorial scales (European, national, regional and local) on the other hand. The integration of the project within the territories can be performed through different forms of territorialisation, both material and immaterial, from the construction of railway equipment to the rearticulation of the roles of the stakeholders within a given territory. We therefore witness a double process of politisation of the local interests through the action of business associations at the regional level, and depolitisation of the debate about the corridor as the project reaches a European level. Three key outcomes emerged from this work based on a methodology relying mainly on interviews as well as the study of planning documentation and the manifestations of the Mediterranean corridor in the public debate. The first idea is that, given its plasticity, the corridor becomes indeed a political subject: it is both a project for infrastructure with evolving characteristics and a catalyst gathering different interests around a common objective. Secondly, as it corresponds to different territorial representations and objectives, the Mediterranean corridor cannot be materialized as infrastructure because this materiality would deprive it from its role as a federator of interests and would therefore destroy the fragile unity that was made possible by its claim. This inherent material impossibility of the Mediterranean corridor is at the same time a fundamental component of its position as a mediator between the different stakeholders. Finally, being at the centre of a territorialisation process that is indeed plural, the Mediterranean corridor echoes all three meanings of this concept: it is one of the avatars of the major European and Spanish spatial structures; it is also a factor of the emergence of new territorial structures at a local scale; and it allows a reorganisation of the interactions of the different stakeholders around a project, within its very own spatial manifestation

Since 1987, the Food Safety and Inspection Service (FSIS) has implemented a zero-tolerance policy for Listeria monocytogenes (Lm) in ready-to-eat (RTE) meat and poultry products, which culminated with the implementation of the Listeria rule in 2003. While researchers have extensively examined human listeriosis and its causative agent, Lm, there remained a significant gap in the current literature regarding how, singly or in combination, establishment size, RTE product type, Listeria alternative used, and FSIS district of production predict compliance with the Listeria rule. Therefore, the purpose of this quantitative study was to investigate the relationship between establishment size, RTE product type, Listeria alternative used, FSIS district of production, and compliance with the Listeria rule. The deterrence theory was used to explain the relationships and associations between variables. Archival Lm sampling data collected between 2012 and 2015 by FSIS was used to analyze the relationships. Chi-square tests showed no significant statistical relationship between establishment size, Listeria alternative used, FSIS district, and compliance, but they did show a significant association between compliance, RTE salt-cured products, and fully cooked products. Additionally, logistic regression analysis showed that the odds of an Lm-positive sample was higher for salt-cured products than for fully-cooked products. This study's findings indicate the need for a reevaluation of FSIS Listeria prevention policy, with a focus on salt-cured products. These results can influence positive social change if used in a targeted public health outreach/education program that focuses on the food safety risks associated with salt-cured products.

This dissertation proposes a Dynamic Message Signs (DMS) diversion control system based on principles of existing Advanced Traveler Information Systems and Advanced Traffic Management Systems (ATMS). The objective of the proposed system is to alleviate total corridor traffic delay by choosing optimized diversion rate and alternative road signal-timing plan. The DMS displays adaptive messages at predefined time interval for guiding certain number of drivers to alternative roads. Messages to be displayed on the DMS are chosen by an on-line optimization model that minimizes corridor traffic delay. The expected diversion rate is assumed following a distribution. An optimization model that considers three traffic delay components: mainline travel delay, alternative road signal control delay, and the travel time difference between the mainline and alternative roads is constructed. Signal timing parameters of alternative road intersections and DMS message level are the decision variables; speeds, flow rates, and other corridor traffic data from detectors serve as inputs of the model. Traffic simulation software, CORSIM, served as a developmental environment and test bed for evaluating the proposed system. MATLAB optimization toolboxes have been applied to solve the proposed model. A CORSIM Run-Time-Extension (RTE) has been developed to exchange data between CORSIM and the adopted MATLAB optimization algorithms (Genetic Algorithm, Pattern Search in direct search toolbox, and Sequential Quadratic Programming). Among the three candidate algorithms, the Sequential Quadratic Programming showed the fastest execution speed and yielded the smallest total delays for numerical examples. TRANSYT-7F, the most credible traffic signal optimization software has been used as a benchmark to verify the proposed model. The total corridor delays obtained from CORSIM with the SQP solutions show average reductions of 8.97%, 14.09%, and 13.09% for heavy, moderate and light traffic congestion levels respectively when compared with TRANSYT-7F optimization results. The maximum model execution time at each MATLAB call is fewer than two minutes, which implies that the system is capable of real world implementation with a DMS message and signal update interval of two minutes.

No description available.

Understanding potential cross contamination pathways is essential to reducing the risk of food product contamination. The use of a fluorescing abiotic surrogate (GloGermTM) to visualize the potential spread of bacteria may be beneficial to researchers. To quantify cross contamination during experimental trials in a mock retail deli, a rating method for visualization of fluorescence levels using a trained sensory panel was developed. Panelists feedback led to a pre-defined strategy allowing for characterization of contamination seen in photographs and reduced variability within responses. Following validation, GloGermTM was used to visually represent how bacteria may spread through a deli environment. Six origination sites (slicer blade, meat chub, floor drain, preparation table, employee's glove, employee's hands) were evaluated separately and spread was photographed throughout the mock deli. The trained sensory panel then analyzed the photographs. Five of the six contamination origination sites transferred GloGermTM to surfaces throughout the mock deli. Contamination from the floor drain did not spread to any food contact surfaces. To determine the potential of using a GloGermTM/ bacteria mixture to simultaneously track and sample contamination spread; surfaces were co-inoculated with GloGermTM and bacteria to determine if co-inoculation would affect the recoverability of microorganisms from these surfaces. Three common foodborne bacteria (E. coli O157:H7,Salmonella enterica ser. Enteritidis, Listeria monocytogenes, Listeria innocua) were inoculated on 2 by 2 stainless steel coupons alone and with GloGermTM . There was no significant difference found (p > 0.05) between the recovery of bacteria alone and the mixture for all bacteria. Finally, the use of co-inoculation was further explored by inoculating two contamination origination sites with either bacteria alone (L. monocytogenes and L. innocua) or a GloGermTM/bacteria cocktail. Nine recipient sites were sampled after a series of deli procedures were performed. Generally, no significant differences (p>0.05) were seen between the transfer of bacteria inoculated alone and the transfer of bacteria inoculated with GloGermTM to the selected recipient sites, regardless of contamination source or bacteria. These results suggest there may be potential in using L. innocua in combination with GloGermTM to visually track and sample contamination from a known source throughout a retail deli environment. / Ph. D.