Effect of essential oils on selected pathogenic bacteria isolated from meat processing

[S. L. Vidaković Knežević]

169 str.

Veterinarska medicina - Bezbednost hrane / Veterinary Medicine - Food Safety

Hranom prenosive bolesti, prouzrokovane bakterijama Salmonella Enteritidis, Salmonella Typhimurium, Listeria monocytogenes i Yersinia enterocolitica, predstavljaju veliki problem za javno zdravlje širom sveta. U ovoj doktorskoj disertaciji izabrani izolati bakterija prenosivih hranom, izolovani u procesu proizvodnje mesa, potvrđeni su MALDI-TOF masenom spektrometrijom, dok je sastav 18 etarskih ulja utvrđen upotrebom gasne hromatografije sa masenom spektrometrijom (GC-MS). Utvrđeno je antibakterijsko dejstvo 18 etarskih ulja i njihove minimalne inhibitorne i minimalne baktericidne koncentracije protiv 16 izolata patogenih bakterija prenosivih hranom. Svi ispitivani izolati formirali su biofilmove na polistirenskim i površinama od nerđajućeg čelika, koje se često nalaze u pogonima industrije mesa. Dokazano je da stepen formiranja biofilmova zavisi od dostupnosti hranljivih materija i temperature. Primenom odabranih etarskih ulja na formirane biofilmove uočena je redukcija istih za 30,93% do 90,28%. Upotrebom SEM zapažaju se mikromorfološke promene na izolatima bakterija tretiranih etarskim uljima origana i timijana u vidu narušenog integriteta ćelija i lize. Etarska ulja origana i timijana u koncentracijama MIC i 2MIC na modelu usitnjenog mesa svinja znatno (p < 0,05) su redukovala broj S. Enteritidis, L. monocytogenes i Y. enterocolitica tokom skladištenja. Međutim, delovanje ovih etarskih ulja nije zapaženo protiv S. Typhimurium. Etarska ulja origana i timijana povoljno su uticala i na senzorska svojstva usitnjenog mesa svinja u vidu duže prihvatljivosti boje i manjeg intenziteta mirisa koji ukazuje na kvar tokom skladištenja na temepraturi od 4 ± 1 °C u aerobnim uslovima. Dobijeni rezultati ukazuju da odabrana etarska ulja mogu efektivno da se koriste u industriji mesa kao prirodna alternativa sintetskim aditivima i dezinfekcionim sredstvima.

Foodborne illnesses, caused by Salmonella Enteritidis, Salmonella Typhimurium, Listeria monocytogenes and Yersinia enterocolitica, are a major public health problem worldwide. In this doctoral dissertation, the selected foodborne pathogens isolated from meat processing, were confirmed by MALDI-TOF MS, while the composition of 18 essential oils was determined using gas chromatography-mass spectrometry (GC-MS). The antibacterial activity of 18 essential oils was evaluated against 16 bacterial strains, followed by determination of minimum inhibitory (MIC) and bactericidal (MBC) concentrations. All of the isolates formed biofilm on two common surfaces found in the meat industry, polystyrene and stainless steel. Formation of biofilm was found to be dependent on the availability of nutrients and the temperature. After treatment with selected essential oils, the reduction in biofilm biomass was in the range between 30.93% and 90.28%. Micromorphological changes on the isolates of the bacteria treated by oregano and thyme essential oils were observed in the form of impaired cell integrity and cell lyses using SEM. Oregano and thyme essential oils (MIC and 2MIC) significantly (p < 0.05) reduced the population of S. Enteritidis, L. monocytogenes, and Y. enterocolitica in minced pork meat during the storage. On the other hand, the effect of oregano and thyme essential oils was not observed against S. Typhimurium in same conditions. Sensory evaluation of oregano and thyme essential oils on minced pork as a food model was conducted and panelist considered that they improved sensory properties, such as color and off-odor, during storage at 4 ± 1 °C under aerobic conditions. The obtained results indicate that the selected essential oils can be effectively used in the meat industry as a natural alternative to synthetic additives and disinfectants.

Salmonella Enteritidis, Salmonella Typhimurium, Listeria monocytogenes, Yersinia enterocolitica, etarska ulja, antibakterijska aktivnost, biofilm, usitnjeno meso svinja, mikrobiološki status, senzorska svojstva

Salmonella Enteritidis, Salmonella Typhimurium, Listeria monocytogenes, Yersinia enterocolitica, essential oils, antibacterial activity, biofilm, minced pork, microbiological status, sensory properties

637.5.07:614.31(043.3)

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