Seafood poisoning and diseases of bacterial origin have received relatively high attention and there are methods available to detect the micro-organisms or their toxins. This has not been the case with biotoxins or viruses, mainly because techniques for their detection have not been widely available. With improvement in the sensitivity, accuracy and capacity of diagnostic techniques, it is reasonable to expect an increase in the number of documented viral infections and a decrease in biotoxin-caused poisoning cases.
Parasites are primarily a problem in freshwater crustaceans and fish. Aquaculture in infected areas demands the implementation of strict controls on each of the links of the chain. The waters and all inputs used to breed the fish must be free of potential human pathogens and parasites and the use of antibiotics must be reduced to the absolute minimum level. Many seafood consumers are not even aware of the fact that fish may carry potentially harmful parasites and there are not many studies published regarding the treatment necessary for their elimination from the flesh of the fish or crabs. Moreover, the tools for identification of parasites in clinical, veterinary and especially food samples are troublesome, fastidious and require expert personnel. It is therefore not surprising that they often remain misdiagnosed. Faster and accurate techniques are required to identify these organisms, as well as the design of processing conditions that kill them if they are present in the product. Under present circumstances where these strict practices are not applied and with the lack of suitable methods for the detection of trematode metacercaria, the export of trematode-infested fish and crabs from endemic regions to other countries may be only a matter of time. What is particularly necessary is a long-term realistic plan to eradicate the parasites from populations where they are endemic and from the food chain. If local producers aim to produce “safe” fish for export only, the importing countries will still view with scepticism the quality and safety of a product coming from a region where the parasite is endemic.
With advances in the fields of genomics and proteomics, together with increased concern about the quality and safety of foodstuffs, it is reasonable to assume that there will be an increase in the number of kits and equipment to conduct identity and safety tests on foodstuffs. Thousands of analyses will then be automatically handled in a much shorter time than required at present. This will impose more stringent conditions on the producers but will also help to diminish the risk associated with seafood consumption, increase the trust of the consumers in the safety of these products, and aid in improving public health by increasing the consumption of seafood.
It is likely that DNA-based techniques will be the favourite approach for species identification, both in single products and in mixtures, because they are easy to use. Even if the DNA is severely degraded, identification and also quantification is very likely to be feasible by using quantitative PCR. Moreover, development of suitable DNA-chips for this purpose is also under way funded by the European Union (Project no QRLT-1999-3047, Development of molecular genetic methods for the identification and quantification of fish and seafood). DNA based techniques are, on the other hand, poorly equipped to determine the geographical origin of biological material. For this latter approach, spectroscopic techniques, such as trace element analysis and distribution of natural isotopes will most likely be the preferred choice. To differentiate wild from cultivated fish and in the absence of a comprehensive database to cover all possibilities, either trace element analyses or nuclear magnetic resonance techniques have proven to be adequate.
Proteomics and NMR methods may have a major application within food authentication to characterize the “quality” of the material, the word quality intended to refer to species and tissue, health status of the organism, contamination levels (or stresses) in the place where it was bred and post-mortem treatment. The last would include stress, freshness, and some processing conditions. Conditions that affect the composition and nutritive value of the foodstuffs will be of particular relevance, and proteomics and NMR based studies can make a significant contribution in this area as well.
Many countries’ fisheries are severely depleted and alternative raw materials will have to be provided either from aquaculture or by using different species. Interestingly, the main aquaculture producers and remaining exploitable fishing grounds for alternative species are in the poorer regions in the world - Asia, Africa and South America.
It is very important that when these countries introduce their products in new markets the “new” consumers are properly informed about the identity and properties of their purchases, which means ensuring that the products are safe, with characteristic organoleptic properties, and that they are correctly labelled and identified. This will help the consumers to become familiar with a new product that they can come to appreciate and be willing to pay for. If, on the other hand, a new species is introduced as a substitute for another species or, even worse, it is deceitfully labelled as something else, consumers will automatically assume that the new species is of lower quality than the “original”. Since it is more difficult to restore a ruined reputation than to acquire one, it is critical to avoid situations that can lead to negative perceptions from the very beginning.
Correct identification of the species and their origin requires the collaboration of the international community. During the first TAFT meeting held in Reykjavik, Iceland in June 2003, Dr Rehbein proposed the creation of an international network of institutions to provide authentic reference samples, since the main problem to authenticate a sample is often the lack of authentic reference material at the location where the analysis is required. It would be most useful to construct a database or a web page containing a list of each species being used as food, with the common names for each species, the location where each common name is indeed common, the scientific name, description of the analyses performed on the species and link to the results (for example, material and methods used for IEF, 2-DE analyses, PCR amplifications, NMR and trace element analyses, etc). This could link to a page containing a figure of how the results look (photograph of the gel or the scan) and, if possible, to a table containing the values corresponding to the figure. For each species, it would also be most helpful to include a link to an institution from which any other institution in the world could obtain samples of authentic material (the costs of preparing the authentic material and sending it should be covered by the requesting institution). The support of an internationally recognized institution could be of great value to establish the infrastructure and the contacts among the relevant interested institutions in each country. FAO will examine the possibilities of taking on this responsibility in relation to the Aquatic Food Product Initiative developed under the direction of the Fishery Industries Division.
