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Jerky Compliance Guidelines
The concern over jerky products, Salmonella, and humidity during thermal processing relates back to a 2003 outbreak from Salmonella Kiambu in Jerky produced in New Mexico. While the absolute linkage between this outbreak and humidity used during thermal processing is debateble becaus it was only a hypothesis of the U.S. Department of Agriculture’s Food Safety and Inspection Service (USDA/FSIS), jerky compliance guidlines were nevertheless developed.
The USDA/FSIS published the revised, third version of the compliance guidlines for the production of jerky products in April, 2012. Although these guidlines are still being finalized by USDA/FSIS, the American Association of Meat Processors (AAMP) has a good grasp on what the final version is likely to include. Through the years, there has been a lot of confusion about the proper thermal processing of jerky products and the acceptability of utilizing the parameters outlined within Appendix A (Compliance Guidlines For Meeting Lethality Performance Standards For Certain Meat And Poultry Products).
The guidelines are “guidelines” and are not intended to set any regulatory requirements. The April 2012, jerky guidlines replace the previous version of the guidance that was last updated in 2007.
Appendix A Lethality Requirements
The Lethality treatment of poultry jerky must acheive at least a 7.0 log reduction of Salmonella spp. as required in 9 CFR 381.150. The lethality treatment of meat jerky should acheive at least a 5.0 log reduction of Salmonella spp. and should also acheive sufficient reductions in the other bacterial pathogens of public health concern (e.g., at least a 5.0 log reduction for E. coliO157:H7 for products containing beef. In addition, the lethality treatment of meat and poultry jerky should acheive at least a 3.0 log reduction in Listeria monocytogenes, although a 5.0 log reduction or greater is desirable for providing an even greater safety margin.
Although Appendix A provides many time/temperature combinations to acheive proper lethality, AAMP recommends that processors take jerky products(meat and poultry) to an internal temperature of 160°F. The goal is to not only acheive lethality of the harmful pathogens, but also to reduce potential spoilage bacteria that may be present and extend shelf life.
Product internal temperature can be measured by inserting a thermocouple probe into the geometric center of a meat/poultry strip. Proper insertion may be difficult because the product is so thin; therefore, USDA/FSIS recommends that establishments slice one piece of jerky twice as thick as normal so that the probe can be inserted. If this thicker piece reaches the lethality temperature, the thinner pieces should be as well.
Appendix A Humidity Requirements
Through University research, it has been demonstrated that without sufficient humidity the product surface may be dry too quickly, and the bacteria (i.e, Salmonella) may become more heat resistant. For this reason, it is crucial that jerky processors prevent drying of the product until the lethality is attained.
If you recall, the April 2007, Compliance Guidline for Meat and Poultry Jerky Produced by Small and Very Small Plants stated:
“The 90% humidity parameter must be applied throughout the lethality treatment for meat and poultry jerky if the lethality compliance guidelines (Appendix A) are used as supporting documentation. The humidity must be maintained at >90% for the time that the product is heated at the temperature specified in Appendix A.”
Although this information was only provided in guidance and was not a regulatory requirement, it caused massive confusion and debate between processors and inspection personnel. This confusion has been clarified in the new April, 2012 guidlines,which also includes other useful information for processors who produce jerky products.
Jerky processors can utilize Appendix A, as long as they address the humidity requirements as identified within Appendix A, which includes the following three options:
- Close the oven dampers to provide a closed system and prevent moisture loss. This would meet the requirements of Appendix A provided that the oven remains sealed for 50% of the cooking time and no less than 1 hour; or
- Continuously introducing steam for 50% of the cooking time and no less than 1 hour; or
- If the relative humidity of the oven is maintained at 90% or above for at least 25% of the total cooking time and no less than 1 hour.
Following Appendix A as written, options #1 and #2 don’t state a specific relative humidity amount that processors must acheive. On the other hand, the scientific literature has shown that at least 27-32% relative humidity should be present during the cooking process to ensure that adequate lethality is attained. This humidity range is only a recommendation and not a regulatory requirement. In any case, the use of a humidity sensor or the use of wet-bulb and dry-bulb thermometers (to measure relative humidity) would enable the establishments to determine whether adequate humidity is being applied. In order to ensure adequate humidity is attained, the establishment should monitor the humidity throughout the lethality treatment.
Dry Bulb/Wet Bulb Temeperature
The dry-bulb temperature refers to the ambeint air temperature. The wet-bulb temperature is the temperature indicated by a moistened thermometer bulb exposed to the air flow. If the dry bulb and wet bulb temperatures are known, then the relative humidity can be calculated by the smokehouse microprocessor, an online calculator, or a smokehouse slide ruler.
Although relative humidity monitoring devices are currently available, it is questionable whether these monitoring devices can withstand the somewhat harsh conditions of a smokehouse. It is highly advised to research these devices prior to any purchase.
A basic wet-bulb thermometer can be prepared by fitting a wet, moisture-wicking cloth around a dry bulb thermometer. To maintain a wet cloth during the process, submerse an end of the cloth in a water supply. The cloth must remain wet during the entire lethality treatment, especially if smoke is applied. If a smokehouse does not currently have the capabilities of measuring dry bulb/wet bulb temperatures, processors should consider building a basic device that can be used in their current smokehouse.
Language Within Appendix A & Guidlines
As the aregulated meat industry currently understands, if statements are made within a cited supporting document, they can be interpreted from a very literal perspective. Appendix A and the jerky compliance guidlines contain several such statements that USDA/FSIS has clarified.
- Sealed Oven – A “sealed oven” is generally defined as one in which the smokehouse doors and smokehouse oven dampers are closed to prevent moisture loss.
- Introducing Steam – The “introducing steam” option is meant to refer to the use of live steam, although it may also apply to establishments that spray water onto hot heating elements, which creates steam that in turn produces humidity in the smokehouse.
- Continuously Introducing Steam – “Continuous” does not mean that the steam is injected for at least one hour during one stage; rather, steam could be injected during stages or time intervals during the lethality, as long as the total amount of time the steam is introduced for adds up to over 50% of the cooking time.
- Rising Wet Bulb Temperature – Processors should be able to demonstrate that the wet bulb temperature is rising for 50% of the cooking time. In many smokehouse schedules, the wet bulb temperature may be increasing and decreasing, depending on the stage of thermal processing. The “rising wet bulb temperature” is meant to represent the overall rise throughout thermal processing until lethality is acheived and not a requirement to occur in every stage of thermal processing prior to lethality.
For many years in the United States, the moisture:protein ratio(MPR) was used to define the shelf stability of jerky products. This is no longer the case, and MPR is only to be used to define the standard of identity of meat products. The USDA’s Standards and Labeling Policy Book define the MPR of certain products. The regulations published in the Food Standards and Labeling Policy Book are for labeling purposes only and must also be acheived in the production of certain meat products. The standards are related to product characteristics that are expected by the consumers.
A moisture:protein ratio refers to the quantity of moisture in a product in relationship to the quantity of meat protein, expressed as X parts (or percent) of moisture for each part (or percent) of meat protein. The MPR requirement for jerky products is 0.75:1 in order to label a product as “jerky”. MPR is an innappropriate indicator of shelf-stability and food safety. Establishments should relate MPR strictly to a labeling aspect of jerky products and not to a food safety control measure.
Food Safety – Water Activity
Water activity (also referred to as Aw), is a more appropriate indicator to verify the jerky is properly dried for food safety purposes. This is because water activity is a better measure of available water (or water that is not bound by other components) for microbial growth. Minimizing available water (e.g., acheiving a proper water activity) is critical for controlling growth of pathogens after lethality has been attained.
The jerky compliance guide provides several suggested water activity options, depending on how the product is marketed.
Aerobic conditions (i.e., product is not vacuum packaged and exposed to oxygen) water activity <0.85
Anaerobic conditions (i.e., product is vacuum packaged and is not exposed to oxygen) water activity <0.91.
USDA/FSIS based these limits on the growth and toxin production limits for Staphylococcus aureus under optimal conditions with and without oxygen present, as defined by the International Commission of Microbiological Specifications for Foods (ICMSF). Establishments that choose to use the limits identified in the USDA/FSIS jerky compliance guideline as support for the shelf-stability of their product may cite the guidline as supporting documentation for these limits and are not expected to provide additional scientific support.
The guidlines provide further clarification that if vacuum packaged jerky products have a water activity level >0.85 and <0.91, they should be kept refrigerated once the package is opened because the product would no longer be considered shelf-stable,since it is exposed to oxygen. Therefore, if the product has a water activity in the range of >0.85 and <0.91 and is in a package that is more than a single serving, the package should be labeled with a statement such as “Refrigerate After Opening” (as described in 9 CFR 317.2(k)). The reference amounts customarily consumed per eating occasion are outlined in 9 CFR 317.312 and the single-serve reference amount for jerky products is 30 grams.
Although the jerky guidlines reference a water activity of <0.91 for vacuum packaged jerky, AAMP cautions meat processors regarding the use of this water activity. AAMP believes that a water activity of <0.91 and >0.85 may be too high, even though, from a pathogen perspective, the product is safe. There are a couple of issues processors should consider. With a water activity of <0.91 and >0.85, the jerky product may no longer meet the MPR labeling criteria of 0.75:1. Also, jerky products are commonly given a shelf life of one year. So a jerky product will be safe from pathogen perspective, but a water activity higher than 0.85 may cause potential product spoilage during the shelf life of the product.
Other Supporting Documentation
Currently, there are a variety of scientific journal articles available regarding jerky processes that contain studies that have been conducted to determine time/temperature/humidity combinations that result in adequate lethality for jerky. This AAMPlifier focuses on the use of the USDA/FSIS jerky compliance guidlines and Appendix A for the thermal processing of jerky because it can be much more universally applied for many meat processors. Moreover, journal articles are being highly scrutinized by inspection personnel, and AAMP doesn’t envision this practice to diminish in the future. This is especially true with the HACCP system validation issues looming.
If an establishment chooses to utilize a journal article as scientific support, it should ensure that the critical operational parameters used in the study match those used in the actual process. If one or more of the parameters are not addressed or do not match the level used in the support, then the establishment’s process may not acheive the same level of lethality as cited in the journal article. In that case, the establishment should document a justification as to why that parameter does not need to be met or measured or why it differs from the support. The establishment should consider whether it is using the same:
- Product (e.g.’species, type-whole muscle or ground)
- Product Formulation
- Product Time/Temperature Combination
- Relative humidity at each stage (including, if reported, using the same humidity levels at the beginning and end of each stage)
- Type or pH of marination (if applicable)
- Smoke (if applicable)
If any of these items described in a scientific journal article differs from the procustion of a processor’s unique jerky product and they are determined to be “critical operational parameters,” then the establishment may find themselves in a debate with inspection personnel that they most likely won’t win. Therefore, the use of the jerky guidlines and/or Appendix A for the thermal processing of jerky os encouraged by AAMP.
Valadation of Jerky Thermal Processing
Although the final guidance for the HACCP system validation has not been published, there are some key elements within the jerky guidlines that should be recognized. They include:
- The identification of the critical operational parameters within the supporting documentation used by the establishment.
- The monitoring/data collection of the critical operational parameters
If the jerky processors are using Appendix A as their supporting documentation, they may consider the potential critical operating parameters of:
- Relative humidity prior to lethality to adhere to one of the three potential humidity requirements
- Internal product temperature
- Proper probe placement
Ideally, processors should have a documented smokehouse schedule that demonstrates that, theoretically, the relative humidity and internal product temperature parameters are being met. As confirmation, processors could document that the parameters are being met using smokehouse charts or data logger documentation.
For example, the smokehouse schedule below demonstrates that humidity is being added for 57.1% of the time prior to lethality (i.e.’ 60 minutes of the 105 minutes), which is in compliance with Appendix A. Due to the fact that the set time for step 4 is based on reaching a specific internal temperature, an analysis of the actual smokehouse cook chart is necessary. Since humidity will never be less that 57.1% of the time, if the smokehouse is fuctioning properly. The smokehouse data will confirm whether the thermal processing schedule is truly in compliance with Appendix A critical operating parameters.
Although the final version of the jerky compliance guidlines have not been published by USDA/FSIS, the April, 2012, version gives a somewhat clear indication of what potential food safety hazards the Agency wants jerky processors to address. The collection and analysis of thermal processing data (i.e.’ dry bulb temperature, wet bulb temperature, relative humidity, internal product temperature,etc.) is going to be crucial to demonstrate that all food safety critical operating parameters have been acheived to control harmful pathogens such asSalmonella and adulterant STECs.
The final version of the jerky compliance guidlines should be released in the Spring,2013. AAMP will be posting any revised versions on the AAMP website(www.aamp.com). When it is published, AAMP will conduct a critical review of the information and update the membership on any new information that may not match what has been provided in this AAMPlifier.
Step/Type/Time/Dry Bulb(°F)/Wet Bulb(°F)/% Humidity/Dampers/Smoke
1 • Surface Prep. • 00:30 • 130 • 0 • 0% • Open • Generator On
2 • Smoke/Cook • 01:00 • 130 • 95 • 28% • Auto • On
3 • Set Color • 00:15 • 145 • 0 • 0% • Auto • Off
4 • Cook • 00:01 • 170 • 158 • 74% • Auto • Off
Internal Temperature = 158°F and hold for at least 0 seconds as stipulated in FSIS Appendix A
5 • Dry • 00:45 • 175 • 120 • 20% • Auto • Off
6 • Dry • 00:45 • 185 • 110 • 10% • Auto • Off