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Study of Microbiological Criteria as Indicators of Process Control or Insanitary Conditions
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Executive Summary
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).
Background
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 US 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 to be applied 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 indicating 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)?
- 3. 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)?
5. 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).
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Last Modified:
March 27, 2009 |
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