The effect of sodium chloride, potassium nitrate and sodium nitrite on the recovery of heated bacterial spores *

Summary The ability of aerobic and anaerobic spores, after various degrees of heating, to produce macrocolonies in media containing different concentrations of sodium chloride, potassium nitrate and sodium nitrite has been examined. The effect of different heat treatments, roughly from F0= 0.0015 to F0= 1.5, on the inhibitory levels of these curing ingredients, showed that the more severe treatments were capable of rendering surviving spores considerably more sensitive to subsequent inhibition by concentrations of the order found in cured meats. To produce this effect, less heating was needed with two Bacillus strains than with three of Clostridium. Sodium chloride and potassium nitrate had quantitatively similar effects. The inhibitory effect of sodium nitrite increased roughly ten‐fold from pH 7 to pH 6.