Antimicrobial Intervention and Process Validation in Beef Jerky Processing
University of Georgia
Drs. Mark A. Harrison, Rakesh K. Singh, Judy A. Harrison, and Nepal Singh
To evaluate the use of a marination step, chemical pretreatment, and drying procedures using either a dehydrator or smokehouse as antimicrobial interventions and process validation in beef jerky processing.
Beef jerky strips were made using either a horizontal-flow dehydrator or a commercial-type smokehouse (set at 33% relative humidity) in combination with either acidified calcium sulfate (1:2 and 1:3 water:calcium sulfate ratios) or chlorine dioxide (500 and 1200 ppm) pretreatments to determine the effectiveness of the treatments in the inactivation of Salmonella, E. coli O157:H7, and Listeria monocytogenes on whole strip beef jerky. Inoculated strips were marinated overnight in a marinade containing water, salt, sugar, nitrite, garlic powder, sodium erythrobate, MSG, Vinegar, Worchestershire sauce, and thyme before drying.
Statistical analysis showed E. coli O157:H7 was reduced by at least 5 logs cfu/strip for all the treatments except for jerky pretreated with the lower concentration of chlorine dioxide and dried in the dehydrator. For L. monocytogenes, 5 log reductions were noted for all the treatments regardless of the drying method. Salmonella was reduced by more than 6.5 logs on jerky strips that were pretreated with the higher concentration of acidified calcium sulfate and dried in the dehydrator and jerky pretreated with the 1200 ppm concentration of chlorine dioxide ands dried in the smokehouse. Populations were reduced almost as well on jerky pretreated with calcium sulfate, both concentrations, and dried in the smokehouse.
There was no statistical difference in the effectiveness of the pretreatments in contributing to the reduction of E. coli and L. monocytogenes, although it is possible to rank them with the higher concentration of acidified calcium sulfate being more effective and the lower concentration of chlorine dioxide being least effective. For Salmonella, both concentrations of the acidified calcium sulfate were the most effective in reducing the populations while the lower concentrations of chlorine dioxide were least effective.
This study is important in that it compared the effectiveness between a smokehouse and dehydrator. Previous studies have used either a smokehouse or dehydrator and did not compare the two. Humidity has been identified as an important processing factor in the manufacture of jerky products. While the humidity can be measured and controlled in a smokehouse, the humidity in a dehydrator in not easily controlled and is greatly affected by the relative humidity in the surrounding atmosphere. While effective treatments may be attained using a dehydrator coupled with an antimicrobial pretreatment, processing jerky in the smokehouse with similar temperature conditions was more effective. In general, the acidified calcium sulfate was a more effective pretreatment than chlorine dioxide. Small processors using dehydrators with little control over maintaining consistent relative humidity conditions within the drying chamber may find the use of antimicrobial treatments beneficial in achieving the desired level of pathogen reduction. This research should help minimize their operating cost while helping them to ensure food safety and public health protection. Plants will, however, need to validate that their methodology achieves these parameters.
The full report on this research can be found on the Fiscal Year 2004 table under the column Food Safety Technologies - Additional Information.