Pathogen inactivation on beef jerky in a commercial-type dehydrator under various moisture conditions
Reimer, Nancy A.
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A small commercial-type dehydrator was modified to add steam during the processing of whole muscle beef jerky. The incoming air’s relative humidity was decreased to15 %- 20% by using a home dehumidifier. Two processing temperatures 62.5°C and 71°C were used to compare the addition of steam for thirty minutes during processing to adding a pan of water for the duration of processing and to a control of adding no moisture. Although steam caused the relative humidity to reach 100%, when the dehydrator's fan was turned on, the relative humidity fell to approximately 30-35%. Effects on the inoculated five strain mixture each of Escherichia coli O157:H7 or Salmonella serovars were examined by direct plating enumeration and enrichment. No significant difference was found between the treatments when organisms were recovered on nonselective media (P> 0.05). A five log reduction was not realized at either temperature. Pathogenic bacteria could be recovered either on direct plating or enrichment after 8 or 6 hours, and water activities were approximately 0.7 and below. Dehydrators used for beef jerky processing should be designed to produce a high relative humidity during heating and prevent condensation from dripping on the product before the drying stage.