Who are the culprits? – Potential contaminants of foods and beverages

The ‘culprits’ of the title are actually extremely diverse, and include both living organisms and what might be referred to as ‘complex biochemical agents.’ This last, somewhat contrived, term is intended to cover viruses, viroids and prions. These latter may be thought of as occupying the evolutionary gap between molecules and living organisms. All of these agents have the ability to contaminate foods and beverages, and the potential to cause food poisoning in different ways and with various degrees of severity ranging from mild enteric discomfort to death. Whilst methods of detection for known pathogens continue to improve, it is also the unknown that we need to be constantly vigilant over. The nature of the unknown is literally unknowable, but some guidance as to what new types of foodborne agents might emerge in the future may be gained by considerations of recent discoveries in microbiology that are helping to (re)define the boundaries of the possible. Consequently, whilst primarily focussing on well-characterised foodborne pathogens, some speculation about the ‘next generation’ has also been included where strictly relevant. Filtration represents one method of removing potentially harmful pathogens from the human food chain. The physical dimensions of these agents is of particular importance in the context of filtration, and rather than attempting to formulate a new classification based on size, it will prove more efficient to make use of existing taxonomic divisions. We need not concern ourselves here with the foundations upon which the various sub-divisions have been arrived at, but merely attempt to draw general conclusions about the size ranges of the various taxons that are relevant here. Let us start with living organisms.