Antibacterial effects of 16 formulations and irradiation against Clostridium sporogenes in a sausage model

• The anti-Clostridial effects of 16 formulations and irradiation were conducted.
• Nisin, nitrite, essential oils (EOs) and organic acid salts (OAS) were used in meat model.
• Nitrite was the most important factor in reducing C. sporogenes.
• Nisin, EOs and OAS also contributed to improve the anti-Clostridial effects.
• Irradiation in combined with formulations are less effective than formulations alone.

The anti-Clostridial effects of 16 formulations consisting of nisin (12.5–25 ppm), nitrite (100–200 ppm), mixed essential oils (EOs) of Chinese cinnamon plus Cinnamon bark (0.025–0.05%) and mixed of potassium lactate plus sodium acetate (1.55–3.1%) against Clostridium sporogenes in a sausage model were evaluated. Further, the anti-Clostridial effects of combined treatments using these formulations with irradiation at 1.5 kGy were also conducted to see if there is any synergistic effect. The antimicrobial effects were evaluated at day 1, 4 and 7 during storage of sausage at 4 °C. Eight formulations that contained low nitrite concentration (100 ppm) and contained either low or high concentrations of other agents could reduce C. sporogenes by 0.69–1.39 log CFU/g meat during 7 days of storage. Eight formulations that contained high nitrite concentration (200 ppm) and contained either low or high concentration of other agents could reduce C. sporogenes by 0.93–1.93 log CFU/g meat during storage. The combined irradiation (1.5 kGy) and formulations are less anti-Clostridial effects than formulations alone, except for the formulations 10, 13 and 16 at day 1 as compared to their equivalents alone. The anti-Clostridial effects of the combined treatments were significantly decreased at day 4 and day 7 while formulations alone maintained well their activity during storage. It is possible that irradiation treatment caused a stress on vegetative cells of C. sporogenes and therefore, there might have the endospores formation which are difficult to eliminate them.