INFLUENCE OF SODIUM-CHLORIDE ON THERMAL INACTIVATION AND RECOVERY OF NONPROTEOLYTIC CLOSTRIDIUM-BOTULINUM TYPE-B STRAIN KAP B5 SPORES - A RESEARCH NOTE

Demand for minimally processed refrigerated foods with reduced salt le vels has stimulated renewed interest in the potential for survival and growth of psychrotrophic, nonproteolytic Clostridium botulinum type B spores. As part of a project to better define food-processing require ments, the heat resistance (75 to 90 degrees C) of nonproteolytic C. b otulinum type B spores was assessed in turkey containing 1 to 3% (wt/v ol) salt (sodium chloride). Heated spores were recovered both on reinf orced clostridial medium (RCM) with lysozyme and on RCM having the sam e salt levels as the heating menstruum. When the recovery medium conta ined no salt, D-values in turkey slurry containing 1% salt were 42.1, 17.1, 7.8, and 1.1 min at 75, 80, 85, and 90 degrees C, respectively. Increasing levels (2 and 3%, wt/vol) of salt in the turkey slurry redu ced the heat resistance as evidenced by reduced spore D-values. Also, apparent or measured heat resistance was decreased with increasing sal t concentration in the heating menstruum and the recovery medium. The z-values in turkey slurry for all treatments were similar, ranging fro m 8.47 to 10.08 degrees C. These data will assist food processors to d esign thermal processes that ensure safety against nonproteolytic C. b otulinum type B spores in cook/chill foods while minimizing quality lo sses.