Atividade antimicrobiana de óleos essenciais sobre Clostridium botulinum inoculado em mortadelas

Abstract

The objective of this work to investigate the antibacterial activity in vitro and in situ of different essential oils and their combinations on C. botulinum type D, and its effects on physic-chemical characteristics of mortadella. To determine the minimum bactericidal concentration (MBC), both from isolated essential oils and combining was used dilution technique in broth with subsequent plating on agar base isolation of C. botulinum. The mortadellas were prepared with combinations of essential oils that presented lower minimum bactericidal concentrations and different levels of sodium nitrite. Samples for microbiological analysis were stored at 25 ⁰C for 20 days, inoculated with 10 5 CFU/g of C. botulinum and samples for physic-chemical analysis were stored at 4 °C for 20 days without inoculum. It was observed that the cinnamon essential oil was the most effective against C. botulinum, followed by oregano, thyme and clove bud with MBC of 0,5%, 1,5%, 2% and 7%, respectively. However, the oils cardamom, sage, basilicon, sicilian lemon, rosemary, ginger and nutmeg, showed no MBC in any of the tested concentrations on C. botulinum type D. For the combinations, all concentrations showed bactericidal effect. In the mortadella treatments with combinations of essential oils and different levels of nitrite have not been completely effective in inhibiting the vegetative cells of C. botulinum, favoring the growth and sporulation, except the treatment 4 that completely inhibits the sporulation. In relation to the physic chemical characteristics of the product, the treatments did not differ among themselves as to lipid oxidation, aw, pH and color, presenting only ef fect of storage time. However, the analysis of sodium nitrite was different (p≤0,05) among treatments resulted in higher reduction in residual nitrite in the mortadella containing only 75 ppm of sodium nitrite, no added of essential oil.