Validation of pepperoni processes for control of Escherichia coli O157:H7

The outbreak of Escherichia coli O157:H7 linked with dry-cured salami in late 1994 prompted regulatory action that required manufacturers of fermented products to demonstrate a 5-log unit reduction in counts of this pathogen during processing. Therefore, pepperoni batter (75% pork:25% beef with a fat content of ca. 32%) was inoculated with a pediococcal starter culture and a five-strain mixture of E. coli O157:H7 (greater than or equal to 2 X 10(7) CFU/g) and stuffed into 55-mm diameter fibrous casings 47 cm in length. The viability of the pathogen was monitored before stuffing, after fermentation, after thermal processing, and/or after drying. Chubs were fermented at 96 degrees F (36 degrees C) and 85% relative humidity (RH) to pH less than or equal to 5.0 and then dried at 55 degrees F (13 degrees C) and 65% RH to a moisture/protein ratio of less than or equal to 1.6:1 (modified method 6 process). Counts of the pathogen decreased about 1.2 log units after fermentation and drying. In subsequent experiments, heating chubs after fermentation to internal temperatures of 145 degrees F (63 degrees C) instantaneous or 128 degrees F (53 degrees C) for 60 min resulted in a greater than or equal to 5-log unit decrease in numbers of strain O157:H7 without visibly affecting the texture or appearance of the product. These data revealed that a traditional nonthermal, process for pepperoni was only sufficient to eliminate relatively low levels (ca. 2 log CFU/g) of E. coli O157:H7, whereas heating to internal temperatures of 145 degrees F (63 degrees C) instantaneous or 128 degrees F (53 degrees C) for 60 min delivered a 5 to 6 log unit reduction in counts of the pathogen in pepperoni.