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

The effect of combinations of 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, or equimolar with nitrite level) and polyphosphate (Curaphos 700; 0, 0.3% w/v), on the growth of Clostridium botulinum types A and B was studied in an experimental pork slurry system, without heating and after two heat treatments (80°C for 7 min and 80°C for 7 min plus 70°C for 1 hr) followed by storage at: 15, 17.5, 20 or 35°C for up to 6 months.
Statistical analyses showed that increasing salt or nitrite levels, adding isoascorbate or nitrate, using the highest heat treatment or decreasing the storage temperature all significantly reduced toxin production by Cl. botulinum . The addition of 0.3% polyphosphate (Curaphos 700) significantly increased toxin production. There were many significant two-factor interactions; the effect of increasing nitrite was relatively less if isoascorbate was present, at 4.5% salt, or at low storage temperature. The presence of isoascorbate also counteracted the increase in toxin production attributed to the presence of polyphosphate.