The Missing Element in Microbiological Food Safety Inspection Approaches, Part 1
The purpose of food safety programs should be to keep harmful agents, that is, chemicals, allergens, extraneous matter (insects, metal filings, rubber, plastic, etc.) and microbes out of the food supply. This article will focus entirely upon enhancing control of pathogenic bacteria in foods by showing the need for improvement in food safety audits as they relate to microbiological risk.
It is often stated, and likely true, that the United States has the world’s safest food supply. Nevertheless, the Centers for Disease Control and Prevention (CDC) have estimated that every year in the United States there are approximately 76 million cases, 325,000 hospitalizations and 5,000 deaths as a result of foodborne disease.[1] The number of multistate Class I recalls has grown over the past decade, despite apparent improvements in reducing the number of foodborne disease events with several different microorganisms. This is a consequence of improved surveillance capability throughout our nation as local, state and federal agencies share information in the context of FoodNet and PulseNet.
Added to the cost in human suffering from foodborne illness, expensive recalls may also occur when food-processing companies become aware that their product is contaminated with a pathogenic microorganism. If such product results in illness, lawsuits from stricken individuals (including class action suits) and other business losses (and possible lawsuits) from shorted customers may also result. Product contamination events typically result in a plant’s suspending production on implicated lines—sometimes for many weeks—until contamination sites are determined and eliminated, their entire food safety system overhauled and appropriate repairs and modifications to equipment and facilities are made before restarting production. The resulting costs of these activities are often in the millions of dollars, not to mention other losses due to public embarrassment and loss of market share. Consequently, the food industry has implemented a number of approaches to food safety inspection through the years, including finished product testing, good manufacturing practices (GMPs) and Hazard Analysis Critical Control Point (HACCP) verification audits. Each of these approaches has its own flaws but forms a part of a larger picture of food safety.
Finished Product Testing
Finished product testing is a type of inspection. Prior to widespread understanding and implementation of HACCP in the United States, many companies relied extensively upon end-product holds and testing to provide assurance of the microbiological safety of their products. There is a flaw in this approach.
The incidence of foodborne contamination that occurs in the industry is likely to be fairly low. A published example of this is found by Cutter and Henning[2] who reported incidences of Listeria monocytogenes between about 1 and 6% in various ready-to-eat (RTE) meat products (Table 1).
L. monocytogenes is considered by many to be a ubiquitous pathogenic organism in the natural environment and can be found in many food-processing environments.[3] Frequent isolation of Listeria spp. from meat-processing environments has resulted in a viewpoint that complete elimination of this organism from RTE meat and poultry processing environments may not be possible with current technology.[4] Consequently, plant environmental, and therefore processed product, contamination with other less environmentally prevalent pathogens (e.g., Salmonella) can be expected to be a good deal lower.
Table 2 below shows that if 1% of a given manufacturing production lot is contaminated, one would need to take at least 299 samples to have a 95% chance of recovering a single positive. It should be pointed out that these tables are based on assumptions of homogeneous contamination, perfect test methods and other considerations that do not reliably occur in the real world. In my experience, finished product contamination is nearly always from the post-processing (e.g., post-CCP) environment[5,6] and is often sporadic.
Clearly, one cannot rely on finished product testing to guarantee food safety. This is one reason why appropriate implementation of HACCP is important. However, there is a role to be played by finished product testing in the context of HACCP plan verification (HACCP principle No. 7). Nevertheless, finished product testing is one small piece of a much larger food-safety puzzle.
HACCP Verification Audits
HACCP is regarded by many as the pinnacle of the food safety system built upon laws and regulations, GMPs and Sanitation Standard Operating Procedures (SSOPs), respectively. The principles of HACCP are well known and include:
1. Hazard Analysis and Identification of Preventatives
2. Identification of Critical Control Points (CCPs)
3. Establishment of Critical Limits (CL) for CCPs
4. Monitoring of CCPs
5. Corrective Actions for Critical Limit Deviations
6. Establishment of Record Keeping System
7. Establishment of Verification Procedures
However, serious risks can be missed when one seeks to audit HACCP in isolation from the rest of a plant’s food safety system. The importance of recontamination of food after a CCP cannot be underestimated.[7] I recall one checklist for a HACCP verification audit many years ago of a company that received previously unwashed tomatoes in field-soiled boxes. These boxes of tomatoes were placed in a controlled atmosphere for ripening, removed at the appropriate time, and the tomatoes were placed on a conveyor that transported them through a proprietary machine that washed the tomatoes. Critical operating parameters for this machine (temperatures and chemical strength) were identified as CCPs that were appropriately controlled and monitored. Subsequently, the tomatoes were placed, by a worker with a large, cloth, blood-stained “bandage” over a cut finger, back into the soiled boxes. A review of the plant records indicated that it had fulfilled all seven elements of HACCP. No objective observer would argue that the product was free of environmental contamination. Clearly there was a failure of appropriate GMP-based prerequisite programs. Nevertheless, our observations were disputed as irrelevant to the HACCP verification. This highlights the importance of combining the two approaches and takes us back to GMPs and GMP auditing.
GMPs and GMP Auditing
GMPs are described in the Code of Federal Regulations (21 CFR 110). Establishment of GMPs is considered prerequisite to HACCP. The industry typically interprets these items and develops audits for them. Common elements that are reviewed in such audits follow: