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Presence of Listeria spp. in traditional meat products treated with natural bioactive compounds (Master thesis)

Κουσουτζή, Παρασκευή Μαρίνα/ Kousoutzi, Paraskevi Marina/ Αειφορικά Συστήματα Παραγωγής και Περιβάλλον στη Γεωργία

Listeria monocytogenes is a foodborne pathogenic bacterium that has been associated with several human infection outbreaks and food recalls worldwide. L. monocytogenes is widespread in nature and colonises soil, plants and the intestine of mammals and is therefore transmitted to humans from food for human consumption. The infection it causes in humans is called listeriosis and is a sporadic and rare disease, but with high mortality rates, particularly among people belonging to susceptible groups of the population, such as newborns, the elderly, pregnant women and immunocompromised persons. Due to its psychrotrophic nature and its ability to survive in very low amounts of oxygen, this bacterium poses a risk to both the food industry and the economy, as well as to public health. L. monocytogenes is a pathogen that is very frequently detected in meat products and its presence is observed at all stages of production, from the animal itself to the shops where meat and meat products are sold. The presence of the bacterium in several types of meat and poultry products therefore calls for precautionary measures to be taken and for controls to be in place at the production, processing and handling levels, as well as for consumers to be informed about their contribution to food safety. In this thesis, the presence of Listeria strains and especially Listeria monocytogenes was studied in combination with the addition of natural bioactive substances as preservatives. Specifically, in the laboratory of the department we prepared 100 g sausages, each of which was added a different natural bioactive substance as a preservative. The bioactive ingredients used were: red wine, white wine, olive oil and orange peel zest. The aim of the study was to investigate the activity of the above natural bioactive substances with regard to the growth and multiplication of L. monocytogenes after inoculation in sausages. The results showed significant antimicrobial activity against L. monocytogenes from the samples containing orange peel zest as a preservative since different citrus species are famous for the abundance of bioactive components, nutrients and functional compounds in the peel. In fact, phenolic compounds such as flavonoids are known to exhibit antioxidant, antiatherogenic, anti-inflammatory, anti-cancer, antiviral, antimicrobial and anti-allergic activity.