Antimicrobial Activity of Essential Oils on Clostridium perfringens Type A Inoculated in Mortadella

Abstract

The antimicrobial activity of essential oils on Clostridium perfringens type A and the influence of such oils on mortadella quality were assessed. The anticlostridial effects of several essential oils and their combinations were identified and some essential oils and their combinations were selected for further study in mortadellas supplemented with 75 ppm sodium nitrite and inoculated with C. perfringens. The growth of C. perfringens in mortadella was not inhibited by nitrite (control treatments of 75 and 150 ppm), but the essential oils presented a significant inhibitory effect. The essential oil of Origanum vulgare presented the highest anticlostridial activity. Moreover, higher concentrations of residual nitrite were found in mortadellas containing essential oils than in controls. PRACTICAL APPLICATIONSClostridium perfringens is an anaerobic bacteria, gram-positive and with the ability to form spores that are highly resistant to environmental conditions and causes two important human illnesses: a relatively mild, classic type A diarrhea and the more serious type C human necrotic enteritis. Approximately 75% of cases of illness due to C. perfringens are attributed to meat, meat products and poultry. Nitrite and nitrate salts are added to cooked meat products to control the growth of sporulated bacteria, however, such salts can react with amines to form N-nitrous compounds, particularly nitrosamines, which are mutagenic, neurotoxic, nephrotoxic and carcinogenic. The natural compounds with antimicrobial activity can be used to reduce them. As high concentration of essential oils may negatively affect the flavor of foods, several combinations of essential oils should be minimized to the concentration required. The growth of C. perfringens in mortadella was not inhibited by nitrite, but the essential oils presented a significant anticlostridial activity shown to be possible to use.

Preservative of Essential Oil Blends: Control of Clostridium perfringens Type a in Mortadella

“…Observing the PCA (Figure 1A) of the essential oils combinations, oregano and clove oils are highlighted with the greatest contribution to the bactericidal effect of the different tested combinations. These results were similar to those obtained by Dias and coauthors [13], who found that blends containing the highest ratios of oregano essential oil were more effective against C. perfringens type A. The phenolic constituents present in essential oils alter the permeability and break the cell membrane leading to the inhibition of functional properties and leakage of the internal content, leading to cell death [25].…”

“…Inoculum maintenance was done according to Dias and coauthors [13]. Inoculum standardization (10 7 CFU/mL) was performed with a growth curve (OD 600 nm) and counting on BHI agar plates, with overlay, supplemented with 0.5% glucose and incubated at 37 °C for 24 h.…”

“…Although several studies have shown that EOs retain their antimicrobial activity when added to food matrices, evaluations typically involve only one EO and their concentrations are generally high [10][11][12]. An alternative to this problem is the study of the antimicrobial activity of several EOs in combinations with each other and / or with other conservation technologies [13]. Some recent studies have been reported in this regard.…”

Essential oil combinations against Clostridium perfringens and Clostridium septicum ‐ the causative agents of gas gangrene

“…This study also demonstrated T. vulgaris to be bactericidal but at a much lower concentration (0Á50 mg ml −1 ). In another study, a handful of essential oils were tested against C. perfringens (Dias et al 2015). The authors of that study found that C. limon, C. paradisi, O. basilicum, R. officinalis and Z. officinale showed no antibacterial activity (MIC) or cidal activity (MBC).…”

“…These two compounds showed an MIC value of 0Á38 mg ml −1 individually against C. perfringens with an MBC value of 0Á75 mg ml −1 each. Dias et al (2015) also tested four essential oils (C. citratus, O. vulgare, S. aromaticum and T. vulgaris) against C. perfringens in various ratios of a combination of three essential oils. That study demonstrated that no synergy was found in any of the combinations tested which somewhat supports the data seen in this current study when two oils were combined.…”