Factors controlling the growth of Clostridium botulinum types A and B in pasteurized, cured meats

A pork slurry system was used to study the combined effect of the following factors on growth of Clostridium botulinum: sodium chloride (2.5, 3.5, 4.5% w/v on water), sodium nitrite (100, 200, 300 μg/g), sodium nitrate (0, 500 μg/g), sodium isoascorbate (0, 1000 μg/g) a polyphosphate (Curaphos 700; 0, 0.3% w/v) and heat treatment (80°C/7 min, 80°C/7 min + 70°C/1 hr) with storage at 15, 17.5, 20 and 35°C for up to 6 months. Increasing nitrite, salt or heat treatment, adding isoascorbate, polyphosphate or nitrate, or reducing storage temperature significantly reduced toxin production. There were many two-factor interactions and the relative effect of increasing nitrite became less in the presence of isoascorbate or high salt levels. Increasing salt or heat treatment, adding nitrate or decreasing storage temperature had less effect if isoascorbate was present. The addition of polyphosphate enhanced the effect of adding isoascorbate.