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

Abstract

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: 0ppm, 100ppm and 200ppm) in addition to EO at concentrations of 0.0%, 0.78%, 1.56% and 3.125% stored at 25°C for 30days. 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 EO, 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 EO treatment. A synergistic effect between NaNO2 and EO was observed. In mortadella-type sausages formulated with 100ppm of NaNO2 and EO 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 EO 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.