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<p>In recent years, numerous multistate foodborne outbreaks have been reported that are often associated with low moisture foods (LMFs). The survival of microorganisms in low moisture conditions has become one of the major concerns in the food industry. With the increasing number of recalls, it is necessary to ensure food safety by developing and validating the process parameters. Establishing a thermal process requires a detailed understanding of the inactivation kinetics of the target pathogen with respect to both the process (temperature, time, equipment) and the product conditions (water activity, composition). Along with the most widely used conventional thermal processing, there has been an increase in the demand for natural or minimally processed foods. As a result, many alternative non-thermal processing approaches that provide antimicrobial benefits while retaining the quality attributes of the food product are under investigation. This research focused on studying the inactivation kinetics of foodborne pathogens <em>Salmonella enteritidis</em> PT30 and <em>Cronobacter</em> <em>sakazakii</em> in powdered LMFs using both the thermal and non-thermal (cold plasma) processing technologies. The efficacy of a dielectric barrier discharge cold plasma equipment was tested against pathogens <em>Salmonella</em> <em>enteritidis</em> PT30 and <em>Cronobacter</em> <em>sakazakii</em> in LMFs at 70 kV, resulting in 3.8 log reduction in <em>Cronobacter</em>, and 4.41 log reduction in <em>Salmonella</em> after 5 min of cold plasma treatment in pea protein. The cellular damage to the pathogens was examined by transmission electron microscopy (TEM), and the reactive oxygen (ROS: OH, O) and nitrogen (RNS: N₂, N₂⁺) species were identified using optical emission spectroscopy. The RMSE for the model was found to be between 0.11 and 0.36 with the low standard error of the parameters (δ, n, and log N₀), which illustrated that the Weibull model was a good fit for the experimental inactivation data. </p> <p>In the thermal processing study, the inactivation kinetic parameters of these pathogens were estimated at 70, 80, and 90 °C at 0.11, 0.22, and 0.33 water activity in pea protein powder. The non-isothermal temperature profiles were simulated by building a two dimensional, axisymmetric heat transfer model of the test cell. The inactivation parameters D_ref, z_T, and z_aw were estimated in MATLAB by using a one-step non-linear regression analysis, which was a combination of the primary log-linear model with the secondary modified-Bigelow model. The model was found to be a good fit, showing lower root mean square error (RMSE) and residuals. Further, <em>Enterococcus</em> <em>faecium</em> was observed to have higher D-values at all the processing temperatures and water activity levels as compared to <em>Salmonella enteritidis</em> PT30 and <em>Cronobacter</em> <em>sakazakii</em>, which provides valuable evidence that <em>Enterococcus</em> <em>faecium</em> can be used as a surrogate microorganism for validating the thermal process for pea protein powder.</p>

<p dir="ltr">Healthcare-acquired infections (HAIs) cause a burden in acute care hospitals in the United States. HAIs are caused by <i>Staphylococcus aureus</i>, along with other pathogens found on high-touch and non-high-touch surfaces in hospital environments (e.g., bed rails, blood pressure cuffs, countertops, and floors). To minimize the growth and cross-contamination of pathogens, it is vital to use disinfectants for surface decontamination. In this work, the impact of different application methods and disinfectant active agents was evaluated for use on different healthcare-related surfaces. The first study examined the cross-contamination potential of an auto-scrubber when used to clean and disinfect a 2m² vinyl floor contaminated with <i>S. aureus</i>. Five EPA-registered disinfectants and a cleaner were used with three application methods. Hydrogen peroxide and quaternary ammonium compounds-based disinfectants significantly resulted in less cross-contamination compared to the cleaner. However, there were no significant differences among the application methods used. In the second study, manual floor cleaning and disinfecting on a two-square-meter vinyl floor with three different moping materials were evaluated to assess their ability to prevent cross-contamination. Evidence showed that there were significant differences among the products used, with Hydrogen peroxide and quaternary ammonium compound products being the most effective. The cleaner caused the most cross-contamination, while cotton mops resulted in significant cross-contamination among materials used. Study three investigated the differences among four application methods used with three different wiping cloths (Cotton, microfiber, and nonwoven) on a 2m² Formica board. A spray surface and wipe method was successful in decreasing <i>S. aureus</i> on the surface. A hydrogen peroxide-based product was most effective in reducing bacteria at contamination areas and minimizing cross-contamination. Microfiber cloth picked up significantly more bacteria at contaminated areas. Post disinfection, there was evidence of cross-contamination at sampling areas regardless of product type, wiping cloth, and application methods used, with the cotton cloth causing the most cross-contamination. Viable bacteria were found on the wiping cloths used and on worker's gloves. Together, this work shows that the use of disinfectants is important in hospital environments. The choice of product, wiping material, and application method are principal in the disinfection process as they influence disinfection failure or success.</p>

<p dir="ltr">Agricultural applications often require human experts with domain knowledge to ensure compliance and improve productivity, which can be costly and inefficient. To tackle this problem, automated video systems can be implemented for agricultural tasks thanks to the ubiquity of cameras. In this thesis, we focus on designing and implementing video analytics systems for real applications in agriculture by combining both traditional image processing and recent advancements in computer vision. Existing research and available methods have been heavily focused on obtaining the best performance on large-scale benchmarking datasets, while neglecting the applications to real-world problems. Our goal is to bridge the gap between state-of-art methods and real agricultural applications. More specifically, we design video systems for the two tasks of monitoring turkey behavior for turkey welfare and handwashing action recognition for improved food safety. For monitoring turkeys, we implement a turkey detector, a turkey tracker, and a turkey head tracker by combining object detection and multi-object tracking. Furthermore, we detect turkey activities by incorporating motion information. For recognizing handwashing activities, we combine a hand extraction method for focusing on the hand regions with a neural network to build a hand image classifier. In addition, we apply a two-stream network with RGB and hand streams to further improve performance and robustness.</p><p dir="ltr">Besides designing a robust hand classifier, we explore how dataset attributes and distribution shifts can impact system performance. In particular, distribution shifts caused by changes in hand poses and shadow can cause a classifier’s performance to degrade sharply or breakdown beyond a certain point. To better explore the impact of hand poses and shadow and to mitigate the induced breakdown points, we generate synthetic data with desired variations to introduce controlled distribution shift. Experimental results show that the breakdown points are heavily impacted by pose and shadow conditions. In addition, we demonstrate mitigation strategies to significant performance degradation by using selective additional training data and adding synthetic shadow to images. By incorporating domain knowledge and understanding the applications, we can effectively design video analytics systems and apply advanced techniques in agricultural scenarios.</p>

Master of Science / Department of Agricultural Economics / John A. Fox / The concept of animal cloning was first introduced to the public’s attention in 1996 with the birth of “Dolly the Sheep,” the first mammal to be cloned. Now, after more than a decade the technology has reached a point of feasibility on a commercial scale. With the publication of the U.S. Food and Drug Administration risk assessment on animal cloning in 2008, a report that concluded that the technology was safe and posed no risk to consumers, the issue has received renewed attention. In this thesis I use survey data to examine attitudes to the use of cloning in animal food production among samples of college students in the U.S., Ireland, France, Honduras, and China. Stated likelihood of consuming meat products from cloned animals is correlated with individual characteristics including socio-demographic variables (gender, and farming background) and attitudinal variables measuring concern about various food technologies. In addition, using ordered logit modeling, we examine how respondents might change their probability of consuming cloned products after being provided with information about scientific assessments about the safety of cloning and possible price reductions for cloned products. The analysis shows that: a) respondents in the U.S. and Honduras were more likely than those in other countries to indicate that they would consume cloned products, b) on average, respondents in all countries increased their stated likelihood of consuming cloned products when informed that the U.S. Food and Drug Administration and the European Food Safety Authority had assessed cloned foods as safe for human consumption, and c) individuals who were opposed to cloning on moral grounds were significantly less likely to consume cloned product and furthermore were less likely to respond positively to information about the safety of cloning.

Thesis (M. Tech. Environmental health) -- Central University of technology, Free State, 2011 / Millions of people in South Africa eat out every day, utilising the food service sector. Although the lack of an effective reporting system makes it difficult to know how many of these people suffer from food-borne illness, statistics from the developed countries show that this number may be significant. There is, therefore, the need to ensure that the food service sector, which encompasses fast food outlets, hotels and similar accommodation outlets offering food and beverage services, restaurants, caterers, etc., implement effective food safety management systems. Internationally, the trend has been that food safety management systems should be based on the internationally accepted Hazard Analysis Critical Control Point (HACCP) principles. In South Africa, the implementation of HACCP as a food safety management system has been driven by international trade requirements where foods are exported to countries such as the European Union or the United States of America. A national regulation requiring HACCP implementation was promulgated in 2003, but compliance is not yet required for the food service sector. Currently, neither of the above mentioned factors put adequate pressure on the food service sector to implement formal food safety management systems. However, increasing international tourism and the hosting of international sporting events has brought this sector under scrutiny. Food handlers have been implicated in many outbreaks of food-borne illness and much research has been done to investigate causal factors in this regard. Food handler training has been proposed as a strategy to improve food safety practices. However, research has shown that the traditional provision of food safety and food hygiene knowledge does not equate to improved food safety behaviours. Some authors postulate that the organisational context, created largely by the management of an organisation, is of greater significance than training. Less research is available on these management factors – defined as the situational factors when discussing organisational culture, or defined as enabling and reinforcing factors when discussing food handler behaviour. This study commenced with the hypothesis that food handlers are not able to implement the correct food safety behaviours in the absence of sufficient management support. This support would require appropriate policies regarding food safety, the provision of training and infrastructure and enforcing the correct behaviours by line management, as a minimum. The aim of this study was to investigate and assess the role of line management in relation to food safety at a prominent South African entertainment facility. In order to achieve this, the following objectives were defined for the study: to conduct a qualitative assessment of the role of management in food safety, to assess the role of management in the provision of food safety training and to assess the role of management in the provision of a basic hygiene infrastructure at the study site in order to allow food handlers to carry out the correct behaviours. The objective of conducting a qualitative study of management practices, policies and resource provision with respect to food safety revealed that there was no formal evidence of management commitment to food safety other than the recent provision of food handler training. The findings also indicated a lack of a formal management system for food safety at the study site. In the exploratory survey of food safety training and knowledge, results showed that only 60 % of staff in the survey had received training. This indicates that at the time of the survey, the study site did not fully comply with the minimum legal requirements for food handler training. The results of the employee survey further indicated that employees were aware of the importance of hand washing although it was not possible to determine whether this knowledge was as a result of the training intervention or prior knowledge. Many of the supervisors were not yet trained in food safety and the impact of the food safety training intervention on related behaviours at the site will require further in-depth assessment. Upon investigating the food hygiene infrastructure provided at the study site to allow food handlers to carry out the correct behaviours, findings indicated that although the personnel hygiene programme addressed most of best practice requirements in design, the implementation of the hand washing requirements was not aligned with accepted norms due to the lack of sufficient hand wash basins. The provision of facilities such as sufficient and conveniently located hand wash basins is a management function and findings suggest that, as a priority, management should ensure that they are not contributing to the lack of implementation of the correct food safety behaviours of food handlers as a result of failing to provide the necessary resources. The results of this study should be of value in the food service sector, specifically hotel kitchens, as a guideline to ensure that management plays an effective role in facilitating food safety management systems. A robust food safety and food hygiene training programme for all levels of the organisation is essential in ensuring adequate knowledge of food safety hazards and correct practices. Training should be supported by daily supervision of food safety controls, management commitment and a work environment that supports the implementation of the correct behaviours. Literature has shown that undesirable practices are often deeply rooted in kitchen culture. It has further been commented that culture changes require a top-down approach which usually involves working with the leadership of the organisation. Important policies and procedures generally originate from the management tiers and will always require the concurrence of management in providing resources, altering priorities or otherwise changing how things are done in the organisation. The results of this study are invaluable in highlighting areas in an organisation that could be targeted to change the kitchen culture. Such changes are primarily the responsibility of management. Ultimately, this study endeavours to contribute to the body of knowledge pointing to the role of social-behavioural aspects in ensuring food safety and thereby consumer well-being.

Thesis (M. Tech. Environmental health) -- Central University of technology, Free State, 2011 / The threat to the world food supply and the concern for public health as a result of food-borne diseases has been established as a constant global problem. The safety of food, in particular, is of significance to consumers and producers alike. Regarding the diseases related to food-borne pathogens, the disease syndromes affecting the entire human body has become inestimable. The focus of the study was to establish the effect of sanitisers, detergents and household storage temperatures on the growth profiles and toxicity of typical food related organisms. The endotoxin, LPS of these Gram-negative organisms in communal growth as compared to pure culture was the focus of the investigation. Pure and communal samples were grown in the presence of the extrinsic stresses including storage temperature. The change in toxicity was measured using the Limulus amoebocyte lysate test and the possible change in the immune response was determined using the porcine-IL-6 test. The first obvious finding was that the overall sensitivity of organisms was similar for the same sanitiser and the same detergent. The sensitivity of the community varied slightly but in principle followed the same pattern as the individual organisms. The LD50 for all growth samples were as follows: 32 X 104 PPM for sanitiser 1 and sanitiser 2, and 16X 104 PPM for detergent 1 and detergent 2. Growth in community was found not to be the arithmetic sum of the individual growth patterns. The detergents had a marked effect on the growth of all samples throughout the growth cycle. The sub-optimum household storage temperatures inhibited the growth throughout the cycle but growth did not cease entirely. This finding may have revealed that the acceptable refrigeration temperatures still allows for pathogen growth and thus for biofilm formation. Furthermore, the response of the community to the extrinsic stresses appears to be entirely different to the pure culture and therefore needs further exploration to address the problem. Regarding the quantification by LAL, it was found that the enumeration of the food-borne pathogens isolated from households might not be indicative of acclimatisation obtained over short periods of time and the causal stress turning these organisms into more or less toxic pathogens. The sanitisers and detergents induced competition in colonial fashion and the growth varied between feast and famine. The extrinsic stresses had a more observable effect on the older biofilm as this was shown by a decrease in toxicity. The toxicity as quantified by porcine-IL-6 yielded a mixture of stimulation levels for the cytokine. The toxicity change indicated by the test showed a variation between lowering and noticeable elevation for pure cultures. A marked elevation in toxicity was detected in community at storage temperature 4°C. The study would suggest that porcine IL-6 is not an accurate biomarker for pyrogenicity since its sensitivity is questionable and its inability to indicate toxicity if there is a possible change in the LPS structure. It should be said that further elucidation is needed to support this finding. Having said all that, it is no surprise that the validation for the two tests favours the LAL procedure. The large room for pre-test stimulation in pigs’ blood also tends to cast a shadow on the IL-6 findings. The findings of the study contribute to the body of knowledge covering the effects and quantitative analysis of toxins in food. This should add to safety assurance by sensitizing the industry regarding the most suitable analytical methodologies to apply.

La sicurezza e la qualità degli alimenti sono tutt’ora un problema critico per i paesi in via di sviluppo. Le diete a basso contenuto di acido folico, per esempio, possono causare gravi problemi di salute, soprattutto nei bambini. Gravi disturbi legati al tubo neurale (DTN) nei neonati possono derivare infatti da madri che hanno insufficiente apporto di acido folico (400-600 g / giorno) durante il periodo di gravidanza. Inoltre, se non adeguatamente protetti o trattati, I prodotti alimentari possono essere vettori di funghi e batteri patogeni rappresentando una fonte potenziale di malattie per l’uomo e una perdita economica per le industrie agro-alimentari. Nella seguente tesi si è quindi quindi studiato il ruolo di batteri lattici selezionati (LAB) in grado di aumentare il valore nutrizionale del latte attraverso la produzione di acido folico durante il processo di fermentazione. Inoltre, ci si è concentrati sul loro uso come "bio-conservanti" contro funghi e batteri, attraverso la sintesi di composti antimicrobici (batteriocine) in grado di inibire la crescita di funghi filamentosi e/o batteri patogeni. / The safety and quality of food are still a critical issue in developing countries. Diets with a low content of folic acid, for example, may cause serious health problems, especially in children. Severe disorders related to neural tube (NTD) in infants may arise from mothers having inadequate intakes of folic acid (400-600 g/dia) during the mother pregnancy period. Moreover foods, when not properly protected or treated, can be vectors of pathogenic fungi and bacteria thereby representing a potential source of human diseases and an economical loss for the food industry. In the following thesis we have therefore investigated the role of selected lactic acid bacteria (LAB) in increasing the nutritional value of milk through the production of folic acid during the fermentation process. In addition, we focused on their use as “bio-preservatives” against fungal and bacterial spoilage, through the synthesis of antimicrobial compounds (bacteriocins) able to inhibit the growth of filamentous fungi and /or pathogenic bacteria.