Atividade antimicrobiana de óleos essenciais de orégano (Origanum vulgare), pimenta rosa (Schinus terebinthifolia) e melaleuca (Melaleuca alternifólia) frente aos patógenos de origem alimentar

Abstract

In recent years, the use of synthetic additives to prevent food spoilage by microorganisms has been a worrying factor for the food industry, given their negative impact on consumer health. In order to overcome this impasse, essential oils have emerged as an alternative, containing compounds and active principles that inhibit the development of microorganisms. The aim of this study was to evaluate the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the commercially obtained essential oils of Tea tree (Melaleuca alternifolia), Oregano (Origanum vulgare) and Pink pepper (Schinus terebinthifolia). For the study, bacterial isolates at a concentration of 3.5 x 107 CFU/ml (0.5 on the Mc Farland scale) of Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922) obtained commercially from the American Type Culture Collection were used. The incubated plates were visually analyzed to determine the minimum inhibitory concentration (MIC). In the wells where inhibition of bacterial growth was observed, 20 μL of the suspensions were collected and sown on Mueller-Hinton agar plates in an oven at 37ºC for 24 hours to analyze bacterial growth and determine the minimum bactericidal concentration (MBC). The mean MIC values for oregano, pink pepper and tea tree essential oils were 2500 μg/ml, 650 μg/ml and 500 μg/ml for the E. coli strains, respectively, while the minimum inhibitory concentration of the treatments was 500 μg/ml for the S. aureus bacterial group. As far as CBM is concerned, the average concentrations for the essential oils of oregano, pink pepper and tea tree were 2500 μg/ml, 625 μg/ml and 5000 μg/ml for the E. coli strains and 1250 μg/ml, 2500 μg/ml and 625 μg/ml for the gram-positive bacteria S. aureus, respectively.