THERMAL-DESTRUCTION OF ESCHERICHIA-COLI O157-H7 IN BEEF AND CHICKEN -DETERMINATION OF D-VALUE AND Z-VALUE

Thermal inactivation of a four-strain mixture of E. coil 0157:H7 was d etermined in 90% lean ground beef, and lean ground chicken. Inoculated meat was packaged in bags which were completely immersed in a circula ting water bath and held at 55, 57.5, 60, 62.5, and 65 degrees C for p redetermined lengths of time. D-values, determined by linear regressio n, in beef were 21.13, 4.95, 3.17, 0.93 and 0.39 min, respectively (z = 6.0 degrees C). Using a survival model for non-linear survival curve s, D-values in beef ranged from 20.45 min (D-1; and there was no D-2) at 55 degrees C to 0.16 min (D-1) and 1.45 min (D-2) at 65 degrees C. When E. coil O157:H7 four-strain cocktail was heated in chicken, D-val ues calculated by both approaches were consistently less at all temper atures. The heat resistance of E. coil 0157:H7 was not altered after r efrigerated or frozen storage of inoculated beef for 48 h. The results of this study will be beneficial to the food industry in designing HA CCP plans to effectively eliminate E. coil 0157:H7 in the meat product s used in this study. (C) 1997 Elsevier Science B.V.