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An investigation of L. monocytogenes in the South African ready-to-eat prepared-fruit industry
Thesis (MScFoodSc)--Stellenbosch University, 2021.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2021
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| _version_ | 1867614110302076928 |
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| access_status_str | Open Access |
| author | Esterhuysen, Michael Keaton |
| author2 | Gouws, Pieter Andries |
| author_browse | Esterhuysen, Michael Keaton Gouws, Pieter Andries |
| author_facet | Gouws, Pieter Andries Esterhuysen, Michael Keaton |
| author_sort | Esterhuysen, Michael Keaton |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MScFoodSc)--Stellenbosch University, 2021. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/123723 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:46:49.940Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2021 |
| publishDateRange | 2021 |
| publishDateSort | 2021 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/123723 An investigation of L. monocytogenes in the South African ready-to-eat prepared-fruit industry Esterhuysen, Michael Keaton Gouws, Pieter Andries Stellenbosch University. Faculty of AgriSciences. Dept. of Food Science. Fruit industry and trade -- South Africa -- Quality control Listeria monocytogenes -- Mortality -- Effect of temperature on Foodborne diseases -- Pathogenesis -- Prevention Fruit -- Postharvest diseases and injuries Food industry and trade -- Management -- South Africa Ready to eat meals (RTE) UCTD Thesis (MScFoodSc)--Stellenbosch University, 2021. ENGLISH ABSTRACT: Listeria monocytogenes is a foodborne pathogen responsible for numerous incidences of foodborne- illness and deaths annually. It is a robust environmental pathogen and can survive a wide range of conditions, both within the natural and food processing environment. L. monocytogenes abundance in soil and nature make it difficult to control in the agricultural setting and thus require adequate management in factories and retailers. Its management within the food industry, especially the ready- to-eat sector is of importance, as these products pose the greatest risk to consumer health, due to the limited measures that can be taken to eliminate this bacterium prior to consumption. This is especially true for prepared-fruit products, which cannot be heat treated due to the negative effects this has on sensory and quality attributes of the final product. Furthermore, fruit is susceptible to contamination pre-harvest due to contamination from soil and irrigation water, where L. monocytogenes thrives as a facultative anaerobic, Gram-positive saprotroph. This requires prepared-fruit producers to prioritise the use of sanitation and disinfection measures, as well as adequately controlling temperatures throughout the supply chain to limit the growth and survival of the organism. This must be complemented with proper monitoring procedures to tailor measures to eradicate potential niches within the food processing environment where this organism can survive as well as ensuring that final products are not contaminated and pose a risk to the consumer. Better understanding of this organism in South Africa is important in the wake of the largest ever recorded listeriosis outbreak which occurred in 2017/2018, especially in the prepared-fruit industry which has limited understanding of their role in controlling L. monocytogenes. This study identified climatic and environmental factors within the agricultural environment that may contribute to the contamination of raw materials used in the production of prepared-fruit products, as well as identified raw materials and areas within the prepared-fruit factory that harboured L. monocytogenes through environmental sampling and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) lineage typing. Findings from melon farms in Limpopo and the Eastern Cape indicated that cooler and wetter temperatures contributed to the presence of Listeria species in the agricultural environment. Samples from the in-house Listeria monitoring program at a prepared-fruit factory in Gauteng indicated the presence of L. monocytogenes (n=49) lineage I and II on raw materials, in the environment and in final products. Sanitisers used for the management of this pathogen were also assessed by interpreting the susceptibility of isolates collected via the Kirby-Bauer disk diffusion method. Chlorine, peracetic acid and a quaternary free sanitiser (QFS) were used, with a repeated measures analysis of variance (ANOVA). This indicated that the source and lineage of L. monocytogenes isolates did not result in significant differences to resistance, furthermore it was found that QFS was the only sanitiser of the three to show efficacy against all isolates collected from the food processing environment. QFS should therefore be used to effectively manage L. monocytogenes. Assessment of common chromogenic media used for the detection of L. monocytogenes in environmental swabbing and final product sampling compared three media in their ability to detect and select for L. monocytogenes. These media were RAPID’L.mono™ (RLM) (Bio-Rad), Brilliance Listeria Agar (BLA) (Oxoid) and Harlequin™ Listeria Chromogenic agar (HAR) (Neogen) with comparison based on the bacterium, source, and lineage of L. monocytogenes, finding that all agars were comparable in their ability to detect L. monocytogenes, however both BLA and RLM supported the growth of contaminating bacteria. This work contributed to better understanding L. monocytogenes in the prepared-fruit industry and elucidated better control and monitoring measures that can be used by industry to ensure food safety. AFRIKAANSE OPSOMMING: Listeria monocytogenes is ‘n voedselverwante patogeen wat jaarliks verantwoordelik is vir talle gevalle van voedselverwante siektes en sterftes. Dit is ‘n robuurste omgewinspatogeen en kan ‘n wye verskeidenheid toestande oorleef, beide in ‘n natuurlike en ‘n voedselverwerkingsomgewing. Omdat L. monocytogenes algemeen in die grond en die natuur voorkom, is dit moeilik om in ‘n landbou- omgewing te beheer en voldoende bestuur in fabrieke en kleinhandelaars is dus noodsaaklik. Die bestuur daarvan binne die voedselbedryf is belangrik, veral in die reg-om-te-eet sektor, aangesien hierdie produkte die grootste risiko inhou vir verbruikersgesondheid omdat daar beperkte maatreëls ingestel kan word om hierdie bakterium voor inname uit te skakel. Dit is veral van toepassing op die voorbereide-vrugte produkte wat nie hitte behandeling kan ondergaan nie as gevolg van die negatiewe effek wat dit op die sensoriese en kwaliteitseienskappe van die finale produk sal hê. Verder is vrugte voor oes vatbaar vir kontaminasie vanuit die grond en besproeiingswater waar L. monocytogenes floreer as ‘n fakultatiewe anaërobiese, Gram-positiewe saprotroof. Dit vereis dat voorbereide-vrugte produsente die gebruik van sanitering en ontsmettingsmaatreëls moet prioritiseer, asook die voldoende beheer van temperatuur regdeur die voorsieningsketting om die groei en oorlewing van die organisme te beperk. Dit moet aangevul word met behoorlike moniteringsprosedures om maatreëls aan te pas om potensiële nisse binne die voedselprosesseringsomgewing, waar hierdie organisme kan oorleef, uit te roei asook om te verseker dat die finale produkte nie gekontamineer word en ‘n risiko vir die verbruiker inhou nie. Beter begrip van hierdie organisme in Suid-Afrika is belangrik na aanleiding van die grootste aangetekende listeriose-uitbraak ooit wat in 2017/2018 plaasgevind het, veral in die voorbereide-vrugte bedryf wat ‘n beperkte begrip het van hul rol in die beheer van L. monocytogenes. Hierdie studie het klimaats- en omgewingsfaktore binne die landbou-omgewing geïdentifiseer wat kan bydra tot die kontaminering van rou materiale wat gebruik word in die produksie van voorbereide-vrugte produkte, sowel as geïdentifiseerde rou materiale en gebiede binne die voorbereide-vrugte fabriek waar L. monocytogenes voorgekom het, deur omgewing-steekproefneming en PCR-RFLP geslagslyn tipering. Bevindinge van spanspekplase in Limpopo en die Oos-Kaap het aangedui dat koeler en natter temperature bygedra het tot die voorkoms van Listeria species in die landbou-omgewing. Monsters van die interne Listeria moniteringsprogram by ‘n voorbereide-vrugte fabriek in Gauteng het die teenwoordigheid van L. monocytogenes (n=49) geslagslyn I en II aangetoon op rou materiale, in die omgewing en in die finale produkte. Saniteerders wat gebruik is vir die beheer van hierdie patogeen is ook geassesseer deur die vatbaarheid van isolate te interpreteer wat versamel is via die Kirby-Bauer skyf diffusie metode. Chloor, perasynsuur en ‘n kwaternêre-vrye saniteerder (QFS) is gebruik, met ‘n herhaalde variansie-analise (ANOVA), wat aangedui het dat die bron en geslagslyn van L. monocytogenes isolate nie ‘n beduidende verskil tot weerstandbiedendheid tot gevolg gehad het nie; verder is daar gevind dat QFS die enigste van die drie saniteerders was wat effektiwiteit getoon het teen al die isolate wat versamel is uit die voedselprosesseringsomgewing en dus gebruik moet word om L. monocytogenes effektief te beheer. Assessering van algemene chromogeniese media wat gebruik word vir die opsporing van L. monocytogenes in omgewings-deppers en finale produk, het RAPID’L.mono™ (RLM) (Bio-Rad), Brilliance Listeria Agar (BLA) (Oxoid) en Harlequin™ Listeria Chromogeniese agar (HAR) (Neogen) vergelyk met ‘n algemene kontaminerende bakterium, bron en geslagslyn van isolaat en het gevind dat alle agars vergelykbaar was, maar beide BLA en RLM het die groei van die kontaminerende bakterium ondersteun. Hierdie werk het bygedra tot ‘n beter begrip van L. monocytogenes in die voorbereide vrugte bedryf en het lig gewerp op beter beheer- en moniteringsmaatreëls wat deur die industrie gebruik kan word om voedselveiligheid te verseker. Masters 2021-10-26T15:21:49Z 2021-12-22T14:17:52Z 2021-10-26T15:21:49Z 2021-12-22T14:17:52Z 2021-12 Thesis http://hdl.handle.net/10019.1/123723 en_ZA Stellenbosch University xix, 151 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Fruit industry and trade -- South Africa -- Quality control Listeria monocytogenes -- Mortality -- Effect of temperature on Foodborne diseases -- Pathogenesis -- Prevention Fruit -- Postharvest diseases and injuries Food industry and trade -- Management -- South Africa Ready to eat meals (RTE) UCTD Esterhuysen, Michael Keaton An investigation of L. monocytogenes in the South African ready-to-eat prepared-fruit industry |
| title | An investigation of L. monocytogenes in the South African ready-to-eat prepared-fruit industry |
| title_full | An investigation of L. monocytogenes in the South African ready-to-eat prepared-fruit industry |
| title_fullStr | An investigation of L. monocytogenes in the South African ready-to-eat prepared-fruit industry |
| title_full_unstemmed | An investigation of L. monocytogenes in the South African ready-to-eat prepared-fruit industry |
| title_short | An investigation of L. monocytogenes in the South African ready-to-eat prepared-fruit industry |
| title_sort | investigation of l monocytogenes in the south african ready to eat prepared fruit industry |
| topic | Fruit industry and trade -- South Africa -- Quality control Listeria monocytogenes -- Mortality -- Effect of temperature on Foodborne diseases -- Pathogenesis -- Prevention Fruit -- Postharvest diseases and injuries Food industry and trade -- Management -- South Africa Ready to eat meals (RTE) UCTD |
| url | http://hdl.handle.net/10019.1/123723 |
| work_keys_str_mv | AT esterhuysenmichaelkeaton aninvestigationoflmonocytogenesinthesouthafricanreadytoeatpreparedfruitindustry AT esterhuysenmichaelkeaton investigationoflmonocytogenesinthesouthafricanreadytoeatpreparedfruitindustry |