SURVIVAL OF ESCHERICHIA-COLI O157-H7 DURING THE MANUFACTURE OF PEPPERONI

This study investigated the growth and survival of Escherichia coli O1 57:H7 during the manufacture of pepperoni to determine whether a 5-log (10)-unit decline in numbers, as recommended by the U.S. Food Safety a nd Inspection Service (FSIS), could be achieved. A range of pepperoni formulations with variations in salt (2.5 to 4.8%) and sodium nitrite (100 to 400 ppm) levels, and with pH (4.4 to 5.6) adjusted by manipula tion of dextrose concentrations were prepared, The batters produced we re inoculated with E. coli O157:H7 380-94 at a level of approximately 6.70 log(10) CFU/g; changes in pathogen numbers, pH, titratable acidit y, and sodium nitrite concentrations were monitored during fermentatio n and drying. With the standard commercial formulation (i.e., 2.5% sal t, 100 ppm sodium nitrite, pH 4.8) E. coli O157:H7 numbers declined by approximately 0.41 log(10) CFU/g during fermentation and a further 0. 43 log(10) CFU/g during subsequent drying (7 days). A regression equat ion was fitted to the data which showed significantly (P < 0.001) grea ter reductions in pathogen numbers in samples with increased salt and sodium nitrite contents and lowered pH. However declines were in all c ases less than the target reduction of 5 log(10) CFU/g.