Place

Utah State University, Logan, UT

Purpose

To evaluate the effects of high humidity (>90%) or wet marinade pasteurization on beef jerky’s characteristics (water activity [Aw], moisture/protein ratio, total aerobic plate count [TAC]) and sensory properties.

Summary

The USDA Food Safety and Inspection Service in March 2004 issued a compliance guideline for beef jerky processors, requiring manufacturers who use time–temperature guidelines for pathogen destruction to take into account the humidity of the oven, especially in high-altitude areas of the country where relative humidity is low. This study compared traditional oven-drying practices to high humidity or wet marinade methods for the water activity, moisture/protein ratio, microbial load and the sensory properties (flavor, texture, appearance).

The study followed the USDA guidelines when conducting four test methods: one oven heating method and three marinade-heating methods. This study demonstrated jerky pasteurized by the nonmarinade method A (oven heating method - 76.6 ºC dry bulb, 54.4 ºC oven wet bulb temperature for 1 hour) had generally lower TACs than jerky from the three marinade pasteurization methods and the highest sensory scores for spice intensity and interior cured color (redness).

Jerky pasteurized before oven drying by method B (long time/low temperature - 54 ºC for 121 minutes in marinade) had higher TACs than other methods. Method C (intermediate time/temperature - 60 º C for 12 minutes in marinade) and method D (short time/high temperature - 70º C for 1 second in marinade) had approximately 2-log reduction in TAC but the jerky was less spicy and somewhat darker than jerky from method A. Extruded jerky (1.5-cm thickness) was similar to intact jerky for spice flavor intensity and interior redness, but required longer drying time to reach the target Aw of 0.85. In addition, the long time/low temperature combinations listed in Appendix A of the USDA time–temperature tables for heat inactivation of pathogens may not adequately control spoilage organisms. Based on this study, it is recommended that processors confirm the efficacy of long time/low temperature marinade heating processes with their own products.

Benefits

Jerky pasteurized before oven drying by method B (long time/low temperature - 54 ºC for 121 minutes in marinade) had higher TACs than other methods. Method C (intermediate time/temperature - 60 º C for 12 minutes in marinade) and method D (short time/high temperature - 70º C for 1 second in marinade) had approximately 2-log reduction in TAC but the jerky was less spicy and somewhat darker than jerky from method A. Extruded jerky (1.5-cm thickness) was similar to intact jerky for spice flavor intensity and interior redness, but required longer drying time to reach the target Aw of 0.85. In addition, the long time/low temperature combinations listed in Appendix A of the USDA time–temperature tables for heat inactivation of pathogens may not adequately control spoilage organisms. Based on this study, it is recommended that processors confirm the efficacy of long time/low temperature marinade heating processes with their own products.