Evaluation of the listericidal effect of oregano essential oil and nisin in fresh pork sausages

MONIKA FRANCISCA KRUGER; KATIA GIANNI DE CARVALHO LIMA; JANINE SILVA; PAULO COSTA SOBRINHO; MARIA TERESA DESTRO; MARISA LANDGRAF; BERNADETTE DORA GOMBOSSY DE MELO FRANCO

Calgary, Alberta, Canada

Conferencia; IAFP 93th Annual Meeting; 2006

Listeria monocytogenes is an important foodborne pathogen that can cause infections in humans with mortality up to 30%. In Brazil, 80% of fresh pork sausages were shown to be L. monocytogenes positive. Herbs essential oils and bacteriocins were shown to be effective antimicrobial agents, with a potential application in food systems. In a previous in vitro study, we demonstrated that the combination of 0.5% oregano essential oil and 200 ppm nisin was able to inhibit the growth of L. monocytogenes in agar plates, presenting a synergistic effect, i.e, the oil enhanced the activity of the bacteriocin. In this study, we evaluated the antilisterial effect of 0.5% oregano essential oil and 200 ppm of nisin in fresh pork sausages. Results indicated that oregano essential oil, used alone, was not effective. Nisin alone caused a 2-log reduction immediately after contact, but during storage the surviving cells presented the same multiplication rate as in the control, keeping the counts 2-log lower up to 9 days. When used in combination, the two antimicrobials caused a 4-log count reduction immediately after addition and, when compared to the control, the multiplication rate of the surviving cells during storage under refrigeration up to 10 days was significantly lower. However, samples containing these antimicrobials in the tested concentrations failed the sensorial acceptance tests. These results indicate that the combination of these antimicrobials can be an additional hurdle for the control of L. monocytogenes in fresh pork sausages, but the final sensorial attributes of the product may hamper their application.