Thermal Properties of Foods

Abstract

We validated the lethality of three time and temperature regimens for commercial processing of whole muscle beef jerky. A total of ca. 8.9 log CFU per strip of multiple-strain cocktails of Escherichia coli O157:H7, Salmonella Typhimurium, or Listeria monocytogenes were separately applied onto the surface of beef strips that were treated as follows: (i) inoculated but not marinated or (ii) inoculated and then marinated. A total of three beef strips for each treatment in each of three trials were separately inoculated with a cocktail of one of the three pathogens and placed on the top, middle, and bottom racks of a loading truck. The strips on the rack were loaded into a commercial smokehouse and cooked and dried for 1.5, 2.5, or 3.5 h at a target temperature of 180 degrees F (82.2 degrees C) with constant (natural hickory) smoking, but without the addition of humidity. Regardless of how the strips were treated or where the strips were placed on the loading rack, drying for 1.5, 2.5, or 3.5 h to a target temperature of 180 degrees F (average of 177.2 +/- 5.6 degrees F [80.7 +/- 3.1 degrees C]), with constant smoke at an initial average relative humidity of 63.1% to a final average relative humidity of 20.9% resulted in a decrease of > or = 7.3 log CFU per strip (> or = 6.9 log CFU/g) for each of the three pathogen cocktails. Of note, marinated strips that were cooked and dried for 2.5 and 3.5 h or nonmarinated strips cooked or dried for 3.5 h also satisfied the U.S. Food Safety and Inspection Service standard of identity (moisture-to-protein ratio < or = 0.8) requirements for jerky.