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ABSTRACT The aim of this work was to determine the bacteriological status of selected RTE foods, associated preparation surfaces and cleaning tools sampled from four retail delicatessens in Johannesburg. An initial pilot study of four RTE foods such as filled baguettes, assorted salads, sliced processed meats and hot meals was conducted in order to set the parameters for the remainder of the study. Results showed that filled baguettes and assorted salads contained the highest bacterial counts and incidences of potential foodborne pathogens. Bacterial counts were obtained from the associated preparation surfaces, whilst cleaning tools were associated with coliform and Escherichia coli, suggesting they may harbour potential foodborne pathogens. For the main study, 60% filled baguettes and assorted salads complied with the microbiological guidelines recommended by the retailer, however fruit salads had the lowest bacterial counts overall. Furthermore, of the food contact surfaces plastic chopping boards were identified as the greatest reservoir for RTE food contamination. Bacteriological analysis in conjunction with scanning electron microscopy showed potential foodborne pathogens associated with cleaning tools. Low numbers of aerobic bacteria and Staphylococcus aureus were associated with disposable plastic gloves, suggesting that good glove practices are used by the food handlers.

The Food Safety Modernization Act (FSMA), specifically the Produce Safety Rule (PSR), requires growers to clean and sanitize food-contact surfaces to protect against produce contamination. The ATP monitoring device is a potential sanitation tool to monitor the efficacy of an on-farm cleaning and sanitation program that could help growers meet regulatory expectations mandated by PSR. The ATP device uses bioluminescence to detect all ATP (found in bacteria and produce matter cells) from a swabbed surface. Little work has been done to test the efficacy of these tools under postharvest conditions. The present study evaluated ATP measurement for postharvest surface cleanliness evaluation. Concentrations of leafy greens (spinach, romaine, red cabbage) (with/without L. innocua) were used as organic matter inocula onto stainless steel, HDPE plastic, and bamboo wood coupons to represent postharvest surfaces. The ATP levels on the coupons were measured using swabs and ATP monitoring device. Results showed that the concentration of L. innocua and leafy greens on a surface had a highly significant effect on the ATP device reading (PL. innocua at 4.5 log CFU/coupon where the ATP device could no longer detect ATP from L. innocua. The type of leafy green on a food-contact surface did not affect the ATP reading (P=0.88). Leafy greens with L. innocua had a higher ATP reading when compared to saline and L. innocua, demonstrating the presence of leafy green matter contributes to ATP reading when combined with L. innocua. The different food-contact surfaces had different ATP readings (P=0.03) and the ATP device did not detect bacterial or leafy green ATP from bamboo wood surfaces (P=0.16). Based upon our results, ATP measurement is an appropriate tool to measure produce or bacterial contamination on stainless steel or HDPE plastic surfaces, however it is not recommended for wood surfaces.

Current trends indicate that American consumers are increasingly selecting products that they believe to be environmentally friendly or "natural." In the kitchen, this trend has been expressed through greater desire for using alternative or "green" sanitizers instead of bleach or other common chemical sanitizers. The purpose of this work was to evaluate the effectiveness of one suggested alternative, tea tree oil, as a food contact surface sanitizer. Three foodborne bacterial pathogens (Listeria monocytogenes N3-031 serotype 1/2a, Escherichia coli O157:H7 strain E009, and Salmonella Typhimurium ATCC 14028) were applied separately onto three different food contact surfaces (high density polyethylene, glass, and Formica® laminate). Tea tree oil (TTO), borax, and vinegar (5% acetic acid) were applied individually as well as in combination for a total of seven treatment solutions. In addition, household bleach (6.15% sodium hypochlorite), sterile reverse osmosis (RO) water, and no applied treatment were used as controls. Treatments were tested using an adaptation of the Environmental Protection Agency DIS/TSS-10 test method, whereby each contaminated surface was treated with 100 µl of test solution and held for 1 min followed by submersion in neutralizing buffer and microbiological plating. Samples (0.1 ml) were plated onto TSA and incubated at 35°C for 48 h prior to colony counting. Bleach reduced microbial populations significantly with greater than 5-log reduction reported for all surfaces (Formica® laminate, glass, and HDPE), against E. coli O157:H7, L. monocytogenes, and S. Typhimurium. TTO produced reductions between four and five logs for E. coli O157:H7, L. monocytogenes, and S. Typhimurium and was not statistically different from the vinegar treatment (P>0.05). All combination recipes, including the borax treatment, failed to produce reductions in microbial populations at levels considered to be appropriate for food contact surface sanitizers. Surface type did not play a significant role in the effectiveness of the treatment (P>0.05). Although TTO and vinegar did reduce pathogen populations on surfaces, reductions were not sufficient enough to be considered an equally effective alternative to household bleach. / Master of Science in Life Sciences

The purpose of this research was to determine if bacteriophage (phage) could be used to treat and reduce the incidence of Listeria in food manufacturing facilities, and thereby reduce the risk of food products being cross-contaminated with Listeria monocytogenes. Listeria incidence in food manufacturing ready-to-eat environments was surveyed at 31 ready-to-eat (RTE) food plants. A total 4,829 samples were collected from all locations. Nine (29%) facilities had zero samples positive for Listeria spp., whereas 22 (71%) had one or more samples positive. The total incidence of Listeria spp. in all RTE food plants was 4.5%. The effectiveness of phage against Listeria was determined when applied to stainless steel, polyurethane thermoplastic, and epoxy. Each material was inoculated with a cocktail containing L. monocytogenes and L. innocua (4 to 5-log10 CFU/cm2) and treated with two different concentrations of phage (2x10^7 and 1x10^8 PFU/cm2). Treated samples were held at 4 or 20°C for 1 and 3h. After treatment with phage, Listeria reductions ranged from 1.27–3.33 log10 CFU/cm2 on stainless steel, 1.17–2.76 log10 CFU/cm2 on polyurethane thermoplastic, and 1.19–1.76 log10 CFU/cm2 on epoxy. Listeria reduction occurred on all materials tested, under all conditions. Higher phage concentration, longer time, and higher environmental temperatures led to significantly (P<0.05) greater reduction of Listeria on stainless-steel and polyurethane thermoplastic. The effectiveness of a phage against Listeria spp. was evaluated in two food manufacturing facilities, operating at either 4°C or 20°C. First, a moderate application of a 2x10^7 PFU/mL phage was applied once per day over three days and samples were collected and analyzed for Listeria at 0, 24, 48 and 72 h. This phage treatment led to a decrease in the incidence of Listeria by 67%. A second application method was studied with phage being applied in the food manufacturing environment in an intensified manner (3 times in 18 hours) at a higher concentration of phage (1x10^8 pfu/mL). This intensified application led to a 32% overall reduction in the incidence of Listeria in the production environment. Applications of Listeria specific phage can be an additional intervention strategy for controlling pathogenic Listeria organisms in food production facilities. / Doctor of Philosophy / Listeriosis is a serious illness caused by the bacterium Listeria monocytogenes. Annually in the United States it is estimated that 95.7% of all listeriosis illnesses are caused by the consumption of contaminated food, and it is generally recognized that L. monocytogenes is caused by cross contamination of ready-to-eat foods from an environmental source. The purpose of this research was to determine if food manufacturing facilities could use bacteriophage (phage) to treat and reduce the incidence of Listeria in food manufacturing plant, and thereby reduce the risk of food products being cross-contaminated with L. monocytogenes. The incident rate of Listeria was surveyed by collecting 4,829 samples from 31 ready-to-eat (RTE) food plants across the United States. Nine (29%) facilities had zero samples positive for Listeria spp., whereas 22 (71%) plants had one or more samples positive. The total incidence of Listeria spp. in all RTE food plant samples was 4.5%. Second, research was completed to determine if phage at different levels reduced Listeria on three common food manufacturing plant materials (stainless steel, polyurethane belting and epoxy flooring). After Listeria was attached to each material (4 to 5-log10 CFU/cm2), they were treated with two different levels of phage (2x10^7 and 1x10^8 PFU/cm2) at two temperatures (4 or 20°C) for 1 and 3 hours. After treatment with phage, Listeria reduction of 93.2 to 99.9% occurred on all materials tested, under all conditions. Finally, two different methods of applying phage (moderate and intensified) in a food manufacturing plant was studied. The moderate application was a single treatment with lower concentration of phage (2x10^7 PFU/mL) once per day for three days, while the intensified treatment was the application of high phage concentrations (1x10^8 pfu/mL) three different times, all in a single day. Both application methods reduced the incidence of Listeria in the food manufacturing plant. The total reduction across all trials was 67% using the moderate application method and 32% using the intensified application of phage.

Master of Science / Food Science Institute / Daniel Y.C. Fung / James L. Marsden / Listeria monocytogenes is known to be an environmental contaminant in food processing facilities. Floor drains in processing environments harbor Listeria spp. due to continuous presence of humidity and organic substrates. The cleaning and washing activities undertaken may translocate the bacterial cells from the drain to the surrounding environment, thus contaminating food products being produced. This study validates the effectiveness of Johnson Diversey ‘Eliminex’ Foaming Drain Cleaner and Johnson Diversey ‘Final Step’ 512 sanitizer for inhibition of Listeria monocytogenes in drain surfaces and evaluates the potential for translocation of L. monocytogenes from drains to food contact surfaces in the surrounding environment using Listeria innocua as a surrogate. A 7x 7 x 8 feet flexi glass chamber was built in which a 10 inch diameter drain mounted on an aluminum cabinet was placed. The drain was inoculated with the surrogate organism, L. innocua, at specific time intervals and then treated with the given chemicals. Sponge samples were taken and bacterial populations were recovered on Tryptic Soy Agar (TSA), Modified Oxford Medium (MOX) and Thin Agar Layer MOX (TALMOX). Stainless steel coupons (6.4 x 1.9 x 0.1 cm) were hung at 3 different heights 1, 3 and 5 feet inside the chamber and cell translocation from the drain on to the stainless steel coupons was studied. Reductions up to 4 Log CFU/area or ml were seen at the drain surface, drain crate, drain pipe and wash water for both free cells and cells entrapped in biofilms Treatment had a significant effect (p<0.05) on the reduction of bacterial cells. The wash water showed the greatest reduction from 8 Log CFU/ml to est. 0.23 Log CFU/ml. The given cleaner and sanitizer were found to be effective for reducing Listeria spp. on drain surfaces. Results for the second part indicated translocation at all three heights with percentage translocation ranging between 2-17%. Significantly higher translocation (p<0.05) was seen at 1 foot, followed by 3 feet and 5 feet indicating the closer the height to the drain, the greater the number of bacterial cells that are able to transfer from the drain to the surrounding environment.

Doctor of Philosophy / Food Science / Daniel Y.C. Fung / James L. Marsden / The ubiquitous nature and continued presence in food processing environments makes Listeria monocytogenes a significant threat in ready-to-eat (RTE) food products. This study was performed in two phases; Phase 1 studied lauric arginate (LAE) as an antimicrobial on food contact surfaces and shredded mozzarella cheese, and use of glucose oxidase (GOX), sodium lactate (SL), and acidified calcium sulfate (ACS) as preservatives in mozzarella cheese; Phase 2 evaluated efficacy of Photohydroionization (PHI) technology to control L. monocytogenes on food contact surfaces, sliced American cheese, and ready-to-eat turkey. Stainless steel coupons, mozzarella cheese, American cheese, and turkey were surface inoculated with a three- or five-strain cocktail of L. monocytogenes. Coupons were treated with 100 and 200 ppm solution of lauric arginate for 5 and 15 min. Mozzarella cheese was treated with different combinations of treatments comprising LAE, GOX, SL, ACS, dextrose, and anticaking agents (free flow 1031 and cellulose). Results indicated up to 2.5 log CFU/coupon reductions and it was concluded that LAE was effective in controlling low levels of contamination of L. monocytogenes on food contact surfaces. In mozzarella cheese, results indicated that lauric arginate provided no additional antimicrobial effect (P > 0.05) as compared to GOX + dextrose. The antimicrobial blends with GOX, SL, and ACS were different (P < 0.05) from the controls but showed no differences (P > 0.05) in their effect in controlling bacterial populations. Results from treatment with PHI unit showed significant (P < 0.05) reduction in bacterial populations. L. monocytogenes populations reduced by 4.37 log CFU/coupon on stainless steel surfaces after 15 min of treatment; 2.16 and 2.52 log CFU/sample reduction on American cheese and ready-to-eat turkey, respectively, after short treatment time of 5 min. Lipid oxidation analyses performed on cheese and turkey samples indicated that the PHI treatment did not affect (P > 0.05) TBAR values. These studies suggest that LAE and GOX as antimicrobials and PHI treatment can be used as intervention strategies in an integrated process to ensure safe production of food. Further research is needed to evaluate applicability of SL and ACS in mozzarella cheese.

No description available.

Dans un contexte de forte évolution des réglementations relatives à l'alimentarité des matériaux, l'industrie cristallière est tout particulièrement concernée vis à vis du plomb à travers son catalogue des arts de la table. Aussi il lui est nécessaire d'avoir une connaissance approfondie des procédés actuellement mis en œuvre pour limiter le relargage du plomb et d'étudier des solutions alternatives. Dans une première approche, la substitution du plomb peut alors être envisagée. La revue bibliographique menée sur la question montre alors les limites d’une telle démarche à commencer par la perte de l’appellation cristal. L’autre solution consiste à la réalisation d’opérations de modification des objets en cristal par traitement ou revêtement de surface. Les deux pistes sont alors étudiées et un procédé pour chacune d’entre elles est proposé. Différents aspects sont regardés permettant de qualifier, évaluer et éventuellement comparer ces protocoles. Enfin, en fonction de leurs aptitudes et performances respectives, ces solutions sont mises en œuvre sur différents types de supports de tailles, formes et couleurs différentes. / In a strong evolution context of release limits in the qualification standards of food contact suitability, especially for lead, it became necessary for the lead crystal glass makers to better understand the processes currently implemented in the manufactories, then to study and to develop new solutions to reduce lead leaching of lead crystal glass items from their tableware catalogs. In a first approach, lead substitution can be considered. The literature review conducted on the question then shows the limits of such approach starting with the loss of lead crystal glass appellation. The other solution consists in modifying lead crystal glass objects by surface treatment or coating. The two tracks are studied and a method for each of them is proposed. Different aspects are looked to qualify, to evaluate and to possibly compare these protocols. Finally, according to their respective capabilities and performances, these solutions are tested on different sized, shaped and colored items.

Les emballages alimentaires existent depuis la nuit des temps, depuis que l'homme transporte des aliments solides ou liquides. Comme tous les matériaux destinés à entrer au contact des aliments, le bois peut être une source de contaminations chimiques et/ou biologiques, il est donc soumis au règlement (CE) 1935/2004 du parlement européen. Cependant en France, la réglementation spécifique « bois » date de novembre 1945. Elle définit les espèces autorisées pour le contact alimentaire. Il existe également une note d'information « bois » de l'agence sanitaires française « DGCCRF » qui détaillent quelques phénomènes de migration entre le bois et l'aliment mais elles sont très peu développées. L'objectif de cette thèse est d'étudier les différents facteurs qui influencent la migration des composés organiques du bois après un contact alimentaire afin de développer une méthodologie d'analyse simple applicable par les industriels de l'emballage. A l'échelle locale, ce projet innovant apporte une réponse auprès des autorités sanitaires françaises et auprès de la filière française emballages bois et palettes. Et fournira des éléments nécessaires pour la mise à jour de la fiche « matériau bois n°2012-93 » et permettront aux industries agroalimentaires d'avoir à disposition une méthode d'analyse de référence. / Food packaging has existed for millennia; ever since man wished to transport solid or liquid foods that were gathered previously. As in the case most materials, wood could be a source of contamination by chemical or biological products. To date, there are no studies available that assess the migration potential of wood components in to food. Food in contact with materials, like wood, is subject to the European Regulation (EC) 1935/2004. In contrast to other materials, there is no specific directive for wooden food contact packaging. In France, the only specific regulation concerning "wood" dates from November 1945 and is very underdeveloped. This thesis aims to study various factors that influence the migration of organic compounds from wood to food when in direct or indirect contact with one another. The final outcome will be a simple methodology that can be applied to industrial packaging. At the national level, this innovative project is in response to the needs of both the French health authorities and the French wood packaging industry. And provide the information necessary to update the information contained in "wood material No. 2012-93” which will, in turn, give the food industry an analytical method and a point of reference.