Foodborne outbreaks have been linked to jerky produced under insufficient thermal processing schedules. Reduction of Escherichia coli O157:H7 and Salmonella serovars during thermal processing of chopped and formed beef jerky was evaluated under two processing schedules representative of those used by large-scale (LS) and small-scale (SS) jerky production facilities. Fresh chopped and formed all-beef jerky batter was inoculated with 5.8 to 7.3 log CFU of E. coli O157:H7 or Salmonella per g, extruded into strips, and thermally processed by LS or SS schedules. A $5.0-log CFU/g reduction of both pathogens occurred with <10% relative humidity and a cumulative process of 44 min at 55.6°C followed by 46 min at 77.8°C into the LS schedule. Additional drying at 77.8°C for 3.5 h was needed to achieve a water activity of 0.67 and a moisture-to-protein ratio (MPR) of 0.77. For the SS process, a $5.0-log CFU/g reduction of both pathogens occurred with 15 to 20% relative humidity and a cumulative process of 45 min at 52°C, 60 min at 57°C, 45 min at 60°C, 45 min at 63°C, 90 min at 68°C, and finishing with 30 min at 77°C. After processing for an additional 90 min at 77°C, water activity was 0.60 while the MPR was 0.82. The LS and SS processes for producing chopped and formed jerky provided $5.0 log lethality to control E. coli O157:H7 and Salmonella. However, both processes would require additional drying to achieve an MPR of 0.75 to be labeled as jerky.
† Contribution 09-133-J from the Kansas Agricultural Experiment Station.