2010-2012 Subcommittee: Study of Microbiological Criteria as Indicators of Process Control or Insanitary Conditions
- Mr. Spencer Garrett: Working Group Chair
- Dr. Robert Dole
- Dr. Kathleen Glass
- Dr. Stephen Knabel
- Ms. Angela Ruple
- Dr. Robert Whitaker
- Dr. Donald Zink
The Department of Defense (DoD) has specific standards for Salmonella, Listeria monocytogenes, E. coli O157:H7, Clostridium perfringens and microbial toxins in certain raw and processed meat, poultry, egg products and many other products such as bagged leafy green salads procured globally for U.S. military personnel. However, there are other bacteria that, when present in higher numbers, may indicate that processing conditions did not adequately prevent or reduce contamination of the product. The DoD has encountered numerous circumstances where numbers of potential pathogens or indicator bacteria have generated concerns about the safety and/or wholesomeness of products. The DoD seeks refined microbiological and other possible criteria to better evaluate process control and insanitary conditions at the point of production. Proposed organisms for the National Advisory Committee on Microbiological Criteria for Food (NACMCF) evaluation are Staphylococcus aureus and Bacillus cereus in ready-to-eat (RTE) products, mesophilic aerobic plate count in raw and RTE products, and other possible indicators of insanitary conditions in food processing establishments (e.g., generic E. coli, coliforms, Enterobacteriaceae, enterococci and gas-forming anaerobes).
The DoD, when procuring food around the world, often sends auditors to evaluate processing conditions within food establishments. Many processors reference microbiological criteria from various entities or have established their own criteria to monitor the safety and/or quality of raw or RTE components of products. Many establishments also use microbiological criteria to monitor process control. Since the U.S. has not published these types of standards recently, the DoD has established their own standards to assist auditors in their evaluation of various processing systems. The existing DoD standards need to be suitable for application to current processing conditions in the region where the food is produced.
The DoD is often faced with using a variety of microbiological criteria in combination with other audit findings to determine whether an establishment is maintaining appropriate process control, or whether product produced in certain circumstances is safe and/or wholesome for military personnel. For potential pathogens such as Staphylococcus aureus and Bacillus cereus, a 5-log level is generally regarded as an indicator level that product that is clearly unsafe for human consumption. However, given the potential for abuse down the distribution chain and the limitations of typical testing plans for addressing the heterogeneity of levels throughout each production lot, it appears that microbiological criteria for these potential pathogens at the time of production might be significantly lower.
Many industry and regulatory laboratories have relied upon organoleptic evaluation of regulated products for quality purposes. While organoleptic examination has its value, it is inherently subjective and dependent upon sensory capabilities that vary from analyst to analyst. Numbers of indicator bacteria such as aerobic plate count might be more effective for determining quality of products that may have been stored for a significant period of time.
Food processors, including those who supply the DoD, are responsible for evaluating individual components of RTE products (e.g., processed meats, cheese, poultry, egg products and spices) received at their establishments, which may be included as ingredients in the final product without further processing to inactivate biological hazards. These establishments often perform microbiological testing on raw materials or require microbiological criteria as elements of a certificate of conformance that accompanies the raw materials. The NACMCF's guidance on the role of microbiological or other indicators to evaluate raw materials or product components in food establishments would greatly support food safety initiatives.
A variety of analytes (e.g., aerobic plate count, generic E. coli, Enterobacteriaceae, coliforms, enterococci) are currently monitored by the DoD, food establishments and other entities, which may indicate insanitary conditions or poor process control. Over the years, various international agencies and other organizations (e.g., Codex Alimentarius) have developed microbiological criteria for many products, but there is no consensus on acceptable microbiological levels in the U.S., where entities with an interest in food safety have been left to develop their own criteria.
Charge Questions for the Subcommittee
Because of the many questions regarding microbiological criteria that might indicate poor process control or insanitary conditions, the National Advisory Committee on Microbiological Criteria for Foods (NACMCF) is asked for its guidance to clarify the following issues.
- Describe processes and important considerations that could be used to develop a microbiological criterion for a particular product (e.g., raw ground beef, RTE sliced luncheon meat) at various points in the process that might indicate poor process control and/or insanitary conditions. Describe how the processes and considerations could differ in other regions of the world where processing conditions may make certain indicators or levels of indicators more or less appropriate.
- At the point of production, how many Staphylococcus aureus, Bacillus cereus, generic E. coli, coliforms, Enterobacteriaceae, enterococci and/or gas-forming anaerobes in RTE finished products might indicate: a) a possible process control problem or insanitary conditions, or b) potentially hazardous product unfit for distribution?
How might the levels and the applicability of these criteria vary between different RTE products (e.g., processed meat, poultry, egg products, refrigerated meat/poultry salads, and bagged leafy green salads)?
- At the point of production, what level of mesophilic aerobic plate count in RTE finished products and in non-intact raw meat and poultry products might indicate a possible process control problem or insanitary conditions?
How might these criteria vary between different RTE products (e.g., processed meat, poultry and egg products, and refrigerated meat/poultry salads)?
How might these criteria vary between different non-intact raw products (e.g., beef trimmings versus ground product)?
How might these levels be expected to change during the expected shelf-life of the product?
- Are there other potential indicators (e.g., microbiological, biochemical or molecular parameters) of process control that should be considered? If so, how might these apply at various points in the process to major product categories (e.g., processed meat, poultry and egg products, bagged leafy green salads and refrigerated meat/poultry salads)?
- Discuss various sampling plans (e.g., International Commission on Microbiological Specifications for Food 2 or 3 class plans) that may be applicable for the various analytes and products identified in the questions above. In the attached table, provide appropriate values [i.e., ranges (log CFU/g), categories (acceptable, marginal, unacceptable)] and if applicable, the recommended sampling plan. (Table 1, PDF Only).