|Title of Research:
New Interventions and Validation for the Control of Pathogens in the
Processing of Jerky
Montana State University, Bozeman, MT
Drs. Jane Boles, K.I. Neary, and K. Clawson
- Determine the survivability of E. coli O157:H7, Salmonella spp. and
Listeria monocytogenes on whole muscle jerky dried without humidity and stored in a vacuum package.
- Determine the survivability of E. coli O157:H7, Salmonella spp., and
Listeria monocytogenes on whole muscle jerky dried with smokehouse dampers closed for the first hour of processing.
- Determine the survivability of Listeria monocytogenes inoculated post-processing on jerky treated with a sodium lactate or hot water dip.
Drying procedures currently used by most small processors
will reduce the number of pathogens on the jerky; however, drying
does not reduce the number enough to meet the 5-log reduction USDA
desires. Closing of the smokehouse dampers for the first hour of
processing resulted in a small significant decrease in E. coli
and Salmonella survival. Salmonella was more susceptible to
the increased moisture during the first hour of drying than were
Listeria and E. coli. Use of sodium lactate dip (2%)
is not as effective as a 20 second hot water dip or no treatment in
decreasing post-processing inoculated Listeria monocytogenes
on jerky. Drying and storing in a vacuum package does result in a
reduction of pathogens but not to below the detectable limit. The
cause of the reduction of pathogens in storage is not clear. Some
will be due to the lowered water activity but some may be due to
pathogens being injured during drying and not being able to adapt to
the vacuum packaged atmosphere. As long as the water activity of
jerky is below 0.70, pathogens will not survive vacuum packaged
storage at ambient temperature beyond 6 weeks.
This study reinforced the importance of maintaining humidity and
controlling the moisture loss from the product in order to achieve
an adequate lethality of the three pathogens especially during the
initial part of drying. It was demonstrated that closing the oven
damper for the first hour of the drying step reduces the amount of
Salmonella spp. and E. coli O157:H7 for all
successive times of drying except for 12 hours of drying. The
results of this study provide reinforcing information on the
importance of maintaining humidity during the processing of jerky to
control the three pathogens, E. coli O157:H7,
Salmonella spp., and Listeria monocytogenes. Something
as simple as adjusting the oven damper during processing shows that
control of humidity can be easy to achieve and cost effective and
thus should be of particular value to small and very small plants
that make jerky. Plants will, however, need to validate that their
methodology achieves these parameters. This research should decrease
their operating cost while helping them to ensure food safety and
public health protection.
The full report on this research can be found on the Fiscal Year 2004 table under the column Food Safety Technologies - Additional Information.