General Information

Agricultural products and animals have a wide range of microbes on, or in, them at harvest/slaughter, whose type vary with commodity, geographic region, and production and harvesting/slaughtering methods. Some of these microbes (bacteria, yeasts, moulds) can grow on the food causing spoilage, which is a common cause of rejection at import. Other pose a hazard to man through illness, having the capacity to infect the consumer, or to intoxicate if they have multiplied in the food and produced a toxin (enterotoxin or exotoxin).

The levels of microbial contamination of food are influenced by harvesting / slaughtering technologies and by the processes applied during food manufacture. With current technologies it is impossible to guarantee the absence of pathogenic microorganisms on raw foods, both of plant and animal origin. Widespread and increasing incidence of foodborne diseases and the resultant social and economic impact on the human population have brought food safety to the forefront of public health concerns. Foodborne illness occurs in every country in ever increasing frequency. Many outbreaks are the consequence of a failed process, or inappropriate storage conditions (usually temperature abuse) during distribution, food service or by the consumer. There are also examples of sporadic outbreaks of illness attributed to raw products eaten unprocessed (e.g. lettuce, melons, raw fish). Foodborne illness has long been linked primarily to foods of animal origin, but in recent years many outbreaks of foodborne illness have been associated with fruits, vegetables and other foods.

There are also examples of imported foods causing human illness, exported from both developed and developing countries. Consequently there is widespread concern that food in international trade carries pathogenic microorganisms that could result in outbreaks of illness. Importing countries have sometimes responded to this concern with measures which are neither scientifically based nor statistically sound, and may be an impediment to fair trade.

Foodborne Illness

Widespread and increasing incidence of foodborne diseases and the resultant social and economic impact on the human population have brought food safety to the forefront of public health concerns. Foodborne illness occurs in every country in ever increasing frequency. Many outbreaks are the consequence of a failed process, or inappropriate storage conditions (usually temperature abuse) during distribution, food service or by the consumer. There are also examples of sporadic outbreaks of illness attributed to raw products eaten unprocessed (e.g. lettuce, melons, raw fish). Foodborne illness has long been linked primarily to foods of animal origin, but in recent years many outbreaks of foodborne illness have been associated with fruits, vegetables and other foods.

There are also examples of imported foods causing human illness, exported from both developed and developing countries. Consequently there is widespread concern that food in international trade carries pathogenic microorganisms that could result in outbreaks of illness. Importing countries have sometimes responded to this concern with measures which are neither scientifically based nor statistically sound, and may be an impediment to fair trade.

Food Inspection and Control

From the earliest records there were religious edicts concerning food handling, e.g. prohibition of meat from animals that died, other than from slaughter. In the following years ordinances, codes of practice and laws concerning the processing, handling and sale of foods have been promulgated by local, national and international bodies with the intention of protecting the public from adulteration, fraud and illness. Adherence to food control regulations regulations has been based mainly upon inspection procedures although it is recognized that inspection as a means of attaining food safety has serious shortcomings. Limited resources in food importing countries normally allow only a fraction of such food to be inspected for safety.

End-Product Testing of Foods

Microbiological testing, as a means of assessing whether a product is microbiologically hazardous has been successfully applied to drinking water, milk, milk products, and egg products to protect public health. Nevertheless, the use of testing to control microbiological hazards in foods has serious limitations. These include:

(i) the problem of sampling and examining a sufficient number of sample units to obtain meaningful information on the microbiological status of a batch of food;

(ii) the difficulty in defining a batch (a lot);

(iii) constraints of time and cost to obtain results; and

(iv) reliable and comparable laboratory methods.

The microbiological safety of food can never be achieved by end-product testing, which only detects that a failure has occurred and can only contribute indirectly to identification and control of the cause of the problem. No sampling plan can ensure the absence of pathogen in a food, and testing products at point-of-production, port-of-entry, or in the retail distribution chain cannot guarantee food safety. All too frequently, industry has become aware of microbiological problems in its products as the result of spoilage in the marketplace or from reports of illness. Control measures are then applied as a response to an existing problem. Furthermore, the isolation of a bacterial pathogen from a food does not mean that the food necessarily is dangerous, e.g. the food may be cooked before consumption. Nevertheless, microbiological testing, used appropriately, is one of the measures that can be used to achieve microbiological safety.

Although diseases seem to be the major microbiological problem related to food, post-harvest losses due to microbial spoilage are a major concern, and significant quantities of food are lost due to microbial spoilage. This is exemplified by food at import often being rejected due to decomposition.

Microbial spoilage, just as foodborne illness, cannot be controlled by end-product microbiological testing, and preventive approaches are required, often as simple as control of storage time and temperature.

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