Influence of reduced levels or suppression of sodium nitrite on the outgrowth and toxinogenesis of psychrotrophic Clostridium botulinum Group II type B in cooked ham.

Outgrowth and toxinogenesis of Clostridium botulinum Group II (non-proteolytic) type B were studied in cooked ham prepared with different NaNO2 (ranging from 0 to 80 mg/kg) and sodium chloride (NaCl, ranging from 12 to 19 g/kg) incorporation rates. Cured ground pork batters were inoculated with a cocktail of 3 strains of C. botulinum Group II type B at 3.5 log10 CFU/g, portioned and samples of 50 g were vacuum packed then cooked and cooled based on thermal processing employed by the meat processing industry. These cooked ham model samples were stored under reasonably foreseeable conditions of use and storage i.e. for 14 days at 4 °C, followed by a cold chain break for 1 h at 20 °C then up to 33 days at 8 °C. Storage times and temperatures were used to mimic those commonly encountered along the supply chain. Enumeration of C. botulinum and detection of the botulinum neurotoxin type B (BoNT/B) were performed in triplicate at different storage times. Under these experimental conditions, incorporation rates of NaNO2 ≥ 30 mg/kg prevented the outgrowth and toxinogenesis of C. botulinum Group II type B in the cooked ham model, regardless of the NaCl concentrations tested. In contrast, total removal of nitrite allowed outgrowth and toxin production during storage of the processed meat product. Results showed that the maximum ingoing amount of nitrite (i.e. 150 mg/kg) that may be added according to the EU legislation (Regulation (EC) No 1333/2008) can be reduced in cooked ham while still ensuring control of C. botulinum Group II type B. According to the multiple factors that could affect C. botulinum behavior in processing meat products, outgrowth and toxin production of C. botulinum should be evaluated on a case by case basis, depending on the recipe, manufacturing process, food matrix and storage conditions.