Hazard Analysis Critical Control Point. Future Directions

The absolute safety of a food can be ensured only by testing each and every bite. In medieval times, the king would employ a taster whose job it was to sample the food prior to the king’s consumption. If and only if the taster survived was the food then fit for a king. Obviously this would be a suitable assay for acutely toxic material, but none of the bacterial pathogens or their toxins would work in such a rapid fashion.

In lieu of this system, end product sampling and testing has certain merits, but given the low statistical probability of an outbreak, the sampling frequency must be high. Furthermore, an assay conducted immediately after processing does not ensure that the product will be safe throughout the projected shelf life, especially if the product is abused or not properly cooked by the consumer.

Hazard Analysis Critical Control Point (HACCP) is an approach to food safety that attempts to predict and then control the specific steps in a given process that, should they fail, will lead to a potentially unsafe product. Originally developed in the 1970s in a joint effort by the National Aeronautics and Space Administration (NASA) and Pillsbury, it applies not only to food processes but to any process where failure can occur due to a problem in one or more steps. In HACCP, the entire process is examined and specific steps in the process or key ingredients are examined to determine which, should they fail to meet a certain specification, might lead to an overall failure in the process.

These steps are then termed critical control points, of which there may be one or more for any given food process. For example, in the processing of fluid milk, the pasteurization step and the need to heat the milk at 145°F for 30 min would be a critical control point. Monitoring of that critical control point might consist of having a thermocouple in the heating section and a flow gauge to determine residence time in the heating region of the pasteurizer. In fact, for several food processes, many critical control points are not only common sense but also standard practice. In other situations, HACCP is only now being considered, and for a few, HACCP is being mandated by regulatory agencies.

Some critical control points may incorporate microbiological testing, for example, with ingredients or between shift cleaning of equipment. Specifically, in a food process where the processing temperatures may not be very severe, ingredients need to be tested to ensure that they are free of Salmonella. Specifications for ingredients are useful because it allows the food processor to produce a food that employs a process that may not be rigorous enough to kill a particular pathogen. They ensure the safety by not allowing a pathogen to contaminate the ingredients.

Future Directions. There will be constant demands to improve the safety of the food supply, which invariably must be balanced against the economic premium that their implementation imposes. The field of risk assessment has been established to weigh various factors in estimating the impact of food safety in terms of potential consequences and likelihood of reducing potential safety problems. A key element in the process of ensuring food safety is the detection of pathogens in the food. Traditional methods for detection rely on growth of the targeted organism under conditions that also aim to suppress the growth of other organisms. Despite their labor intensity and relatively long time to completion, growth-based microbiological methods are still the standard methods for detection.

Modern technology for ensuring the safety of foods is being developed, driven principally by the need to develop quick methods for diagnosis of human disease. One of the more fundamental differences in opinions among food microbiologists is the use of indicator organisms as a sentinel for the presence of pathogens. The use of indicators is not a new concept, in terms of both qualitative and quantitative specifications. One global indicator that is attracting increased attention is the quantification of adenosine triphosphate (ATP) levels to determine relative biological loads. On processing equipment that contacts food, cleaning practices should reduce the biological load to negligible levels. ATP levels can be rapidly assessed using biological reagents that were originally characterized in fireflies.

The enzyme luciferase in the presence of ATP and luciferin emits a photon of light that can be quantified using a luminometer. The process is very rapid and typically results can be obtained within 5 min. The development of low-cost lumino-meters and the accessory reagents have spurred the use of ATP as a measure of total microbial load and hence cleanliness. Yet how this measure relates to the potential for pathogen contamination is difficult to predict. The primary value of ATP measurements may lie in their integration into a HACCP plan. It can then provide a measure of assurance that cleaning and anticipated reductions in the microbial load are achieved on a regular basis.

Specific tests for pathogens will continue to be improved in terms of specificity and speed. One likely assay format to be incorporated into food pathogen tests is the polymerase chain reaction (PCR). This method for amplifying nucleic acid sequences as delineated by a set of oligonucleotide primers is a very powerful means to detect target sequences that uniquely define, for example, a bacterial pathogen.

The speed at which these sequences can be amplified opens new avenues for the development of unique tests to look for virtually any pathogen in any food system. However, there are obstacles to be overcome, which in part involve the purification of the targeted DNA sequence from the food matrix with an efficiency that is consistent with a need to detect very small numbers of bacteria in relatively large food samples.

Bibliography. Oliver, D. O. (ed.) (1990). “Foodborne Diseases.” Academic Press, San Diego.
Jay, J. M. (ed.) (1996). “Modern Food Microbiology,” 5th Ed. Chapman Flail, New York.