CONTROL OF ENTEROTOXIC BACILLUS-CEREUS ON POULTRY OR RED MEATS AND INBEEF GRAVY BY GAMMA-IRRADIATION

The gamma-radiation resistance of five enterotoxic and one emetic isol ate of Bacillus cereus vegetative cells and endospores was tested in m echanically deboned chicken meat (MDCM), ground turkey breast, ground beef round, ground pork loin and beef gravy. The D-10 values for B. ce reus ATCC 33018 were 0.184, 0.431 and 2.56 kGy for logarithmic-phase c ells, stationary-phase cells, and endospores at 5 degrees C on MDCM, r espectively. Neither the presence nor absence of air during irradiatio n significantly affected radiation resistance of vegetative cells or e ndospores of B. cereus ATCC 33018 when present on MDCM. Irradiation te mperature (-20 to +20 degrees C) did affect the radiation resistance o f stationary-phase vegetative cells and to a limited extent that of sp ores on MDCM. Impedance studies indicated that surviving vegetative ce lls were severely injured by radiation. A dose of 7.5 kGy at 5 degrees C was required to eliminate a challenge of 4.6 x 10(3) B. cereus ATCC 33018 from temperature-abused MDCM (24 h at 30 degrees C). The radiat ion resistance of a mixture of endospores of six strains to gamma radi ation was 2.78 kGy in ground beef round, ground pork loin and beef gra vy, but 1.91 kGy in turkey and MDCM. The results indicate that irradia tion of meat or poultry can provide significant protection from vegeta tive cells but not from endospores of B. cereus.