Dehydrator cookbooks don’t always mention preheating the beef before drying it. Yet the United States Department of Agriculture now recommends pre-heating the beef's internal temperature to 160 degrees Fahrenheit, before dehydrating. This is to destroy harmful bacteria, such as salmonella and E.coli. Since most food dehydrators do not reach 160 degrees, it is necessary to do this step in the oven or by steaming. Use a meat thermometer to verify the beef reached 160 degrees F before proceeding. You can’t destroy the harmful bacteria by bringing the jerky up to 160 degrees F after you have finished the drying process. Drying makes the bacteria heat-resistant. Therefore, drying will make the bacteria stronger and able to survive 160 degrees F.
Always wash your hands and all utensils and preparation surfaces before preparing the beef. If you decide to marinate the raw meat before drying it, do this in the refrigerator. Use a lean piece of beef, and trim off and discard any fat. Bring the meat’s internal temperature up to 160 degrees F by steaming it or in the oven. Cut the meat into thin strips, about a 1/4-inch thick. For uniform drying, keep the pieces all about the same size. Lay the strips on the drying trays in a single layer, without overlapping the pieces.
The USDA recommends drying beef jerky at a temperature between 130 and 140 degrees F, and consistently maintaining that temperature during the drying time, which might take up to 10 hours.
The Drying Process
Homemade jerky has a shelf life of about two months. The principle behind dehydration is that bacterial and fungal enzymes are unable to react effectively in food without moisture. Dehydration removes the moisture, thus inhibiting harmful enzyme action. Drying at 130 to 140 degrees F is not warm enough to kill pathogenic bacteria, which is why it is necessary to preheat to 160 degrees F prior to dehydration.