Evaluation of Two Thermal Processing Schedules at Low Relative Humidity for Elimination of Escherichia coli O157:H7 and Salmonella Serovars in Chopped and Formed Beef Jerky

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 degrees C followed by 46 min at 77.8 degrees C into the LS schedule. Additional drying at 77.8 degrees 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 degrees C, 60 min at 57 degrees C, 45 min at 60 degrees C, 45 min at 63 degrees C. 90 min at 68 degrees C, and finishing with 30 min at 77 degrees C. After processing for an additional 90 min at 77 degrees 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.