As I suspected...The 90%RH becomes critical at the lower temp processing, IT of 130 to 145°F, of
Commercial Jerky production.
NOTE: Appendix A is the standard Pasteurization chart with processing time at various temps.
The humidity options in Appendix A that are applicable to jerky processing are: o Heating jerky to a minimum internal temperature of 145 °F (62.8 °C) in an oven maintained at any temperature if the relative humidity of the oven is maintained either by continuously introducing steam for 50 percent of the cooking time or by use of a sealed oven for over 50 percent of the cooking time, or if the relative humidity of the oven is maintained at 90 percent or above for at least 25 percent of the total cooking time but in no case less than 1 hour; or o Heating jerky in an oven maintained at any temperature that will satisfy the internal temperature and time combinations from the chart provided in 19 Appendix A if the relative humidity of the oven is maintained at 90 percent or above for at least 25 percent of the total cooking time but in no case less than 1 hour. The relative humidity may be achieved by use of steam injection or sealed ovens capable of producing and maintaining the required relative humidity.
While 145 may be common for Commercial Production it would require specialized control and monitoring. Not something one should attempt without more detailed training . Kind of like adding Cure #1 to make Kielbasa verses having the skill and specialized equipment to ferment and Dry Cure an Italian Salami for several months.
In general, SMF and the most common recipes for Home Production includes heating to an IT of 165°F during the beginning of smoking or before dehydrating at 130 to 140. Below is an excerpt from the FSIS/USDA Fact Sheet on Homemade Jerky Safety with no mention of maintaining any % RH. Heating to 165 at the start kills all active bacteria in seconds so there is no time for the bacteria to become heat resistant as it could at lower temps.
http://www.fsis.usda.gov/wps/portal...at-preparation/jerky-and-food-safety/ct_index
Why is temperature important when making jerky? Illnesses due to
Salmonella and
E. coli O157:H7 from homemade jerky raise questions about the safety of traditional drying methods for making beef and venison jerky. The USDA Meat and Poultry Hotline's current recommendation for making jerky safely is to heat meat to 160 °F and poultry to 165 °F before the dehydrating process. This step assures that any bacteria present will be destroyed by wet heat. But most
dehydrator instructions do not include this step, and a
dehydrator may not reach temperatures high enough to heat meat to 160 °F or 165 °F.
After heating to 160 °F or 165 °F, maintaining a constant
dehydrator temperature of 130 to 140 °F during the drying process is important because:
- the process must be fast enough to dry food before it spoils; and
- it must remove enough water that microorganisms are unable to grow.
Why is it a food safety concern to dry meat without first heating it to 160 °F?
The danger in dehydrating meat and poultry without cooking it to a safe temperature first is that the appliance will not heat the meat to 160 °F and poultry to 165 °F — temperatures at which bacteria are destroyed — before the dehydrating process. After drying, bacteria become much more heat resistant.
Within a
dehydrator or low-temperature oven, evaporating moisture absorbs most of the heat. Thus, the meat itself does not begin to rise in temperature until most of the moisture has evaporated. Therefore, when the dried meat temperature finally begins to rise, the bacteria have become more heat resistant and are more likely to survive. If these surviving bacteria are pathogenic, they can cause foodborne illness to those consuming the jerky.
I hope this addresses your concerns...JJ
