Antimicrobial activity of Satureja montana L. essential oil against Clostridium perfringens type A inoculated in mortadella-type sausages formulated with different levels of sodium nitrite

This research evaluated the antimicrobial effect of the winter savory (Satureja montana L) essential oil (EO) against Clostridium perfringens type A (ATCC 3624) inoculated in mortadella-type sausages formulated with different levels of sodium nitrite (NaNO2: 0 ppm, 100 ppm and 200 ppm) in addition to ED at concentrations of 0.0%, 0.78%, 1.56% and 3.125% stored at 25 degrees C for 30 days. The EO extracted by hydrodistillation and analyzed by gas chromatography-mass spectrometry (CG-MS) was tested in vitro using an agar well diffusion method for determination of minimum inhibitory concentration (MIC) on C. perfringens. According to compositional analysis of the winter savory ED, 26 chemical compounds were identified, and the major constituents were thymol (28.99%), p-cymene (12.00%), linalool (11.00%) and carvacrol (10.71%). The results obtained showed that EO applied at a concentration of 1.56%, which was defined as the MIC, exhibited antimicrobial activity against C. perfringens in the in vitro assays, and the transmission electron microscopy (TEM) revealed structural damage and cell lysis of C. perfringens caused by ED treatment. A synergistic effect between NaNO2 and ED was observed. In mortadella-type sausages formulated with 100 ppm of NaNO2 and ED at all concentrations tested, the population of target microorganisms was reduced (p <= 0.05) compared to control samples during all storage period. This data suggests the potential combined use of savory ED and minimal amounts of the synthetic additive, NaNO2 to control C. perfringens in mortadella, which goes according to current market trends, where consumers are requesting natural products. (C) 2010 Elsevier B.V. All rights reserved.