Common Food Contaminants and Their Detection

A recent article in one of the British online news magazines suggested that, unknowingly, many of the nation’s consumers could be ingesting enough plastic each week to manufacture a credit card. Whether this is simply another example of media alarmism or a verifiable statistic may, of course, be questionable, but nevertheless, the risks posed by other possible food contaminants are a matter of record, and it is a possibility about which both producers and consumers in all countries, including South Africa, need to be seriously concerned.

Over the past half-century or so, the gradual transition from our former dependence upon natural produce, with which to prepare home-cooked meals, to the willing acceptance of processed foodstuffs, has been partly the result of a desire for convenience and partly an unavoidable necessity in the face of a burgeoning world population. Processing, however, leads to increased handling and, with that, comes a significant increase in the likelihood that these manufactured food products could contain contaminants.

The source of these unwanted contents can sometimes be traced to the raw ingredients used to prepare a product, and so, manufacturers seek assurances based on stringent quality control measures, which are thus incumbent upon their suppliers. However, the most common sources of contamination are, invariably, to be found in the working environment. Typically, these can be the result of contact with a factory’s employees, with its work surfaces, or with its various items of equipment, but could also be atmospheric in origin. In addition, the contamination can take one of three possible forms. It can either be physical, chemical, or biological.

Among the more common physical food contaminants are fingernail fragments, strands of hair, and pieces of plastic or metal from damaged equipment. Excluding foreign bodies, such as these, is largely a matter of instituting preventative measures, such as providing caps and gloves for workers, and conducting regular inspections and maintenance of the processing equipment.

Chemical contamination can occur when, for example, residual traces of herbicides, pesticides, or of cleaning products remaining on a work surface, or when potential allergens are accidentally introduced into a product that would not normally contain them. The latter are, perhaps, among the most dangerous of the chemical food contaminants, and manufacturers are mandated to report their presence or, where a known risk exists, to state that they cannot rule out their presence. All, however, need to be checked for.

Biological contamination is undoubtedly the biggest fear faced by producers, as it can pose the most widespread threat to consumers. This was demonstrated in Polokwane only too well by the 2017-18 outbreak of Listeriosis, a form of food-poisoning, which infected more than a thousand people and claimed 216 lives. The bacterium occurred in polony, but is also found in raw vegetables and various dairy products. Rapid screening tests for the presence of microorganisms are absolutely essential in order to eliminate the risk posed by biological food contaminants, such as Listeria, Salmonella, Shigella, Campylobacter, and E. coli.

Where once, their detection required inoculating culture media and overnight incubation followed by tests to identify possible pathogens, tests based on the detection of ATP can now achieve this in minutes. These and rapid tests for pesticide residues and other chemical food contaminants are available in South Africa from IEPSA.

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