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		How fresh is your fish?       The fish so enticingly displayed on the counter in the supermarket may look fresh, but the chances are that no-one, least of all the supermarket, knows how old it is or where it came from. To do something about this surprising state of affairs, fish research scientists from 14 countries took part in a three-year project to pool their knowledge and come up with better, objective methods of testing the freshness of fish.   Fresh gills: gills are a characteristic red colour and mucus is absent; spoiled gills: gills are discoloured with excessive mucus.. The idea of a concerted action to investigate methods of testing fish freshness arose at a meeting of the Western European Fish Technologists Association in Gothenburg in 1994. "That was the first year that Iceland was eligible for research grants from the European Community and we were eager to benefit from that," says Gudrun Olafsdóttir of the Icelandic Fisheries Laboratories. "So we initiated the idea to have a common project on the evaluation of fish freshness." At present, fish are graded by simple indicators of appearance, touch and smell, a traditional approach which goes under the rather grand name of sensory analysis. "Sensory analysis has always been the method of choice," explains Mrs Olafsdóttir. "But scientists have been trying to find rapid analytical methods that are more objective." Most fish is graded according to the "EU scheme", which places it in one of three classes, the lowest being unfit for human consumption. But there is widespread agreement that the EU scheme is too crude and something better is needed. Changes in sensory attributes of ocean perch during storage. Fresh head: eyes are clear and concave ; spoiled head: eyes are cloudy and sunken.. Quality Index Method One alternative is the Quality Index Method (QIM). "It's more accurate than the EU scheme because you look at each characteristic and you grade it. You look at the eyes, the gills, the skin, and so on, and you add all the scores to get an overall grade for the quality of that fish." QIM first came from Australia, and is now used in the Nordic countries and elsewhere in Europe. The aim of the FAIR concerted action, involving fish and food research laboratories in 14 countries, was to evaluate these methods objectively, investigate whether any new methods could be used - especially rapid instrumental methods - and make recommendations to the fish industry. Apart from sensory analysis, the partners looked at the work that had been done on the chemical and biological changes that occur when a fish starts to decompose, and investigated many methods of detecting these changes. They looked at the growth of bacteria, the breakdown of proteins and fats, the decay of ATP - an energy-carrying molecule that breaks down rapidly after death - and the emission of volatile organic compounds, which produce the characteristic fishy smell. Physical methods included measurements of texture, structure of muscle tissue, electrical properties, colour and spectroscopic measurement, and the use of indicators to record the time-temperature history of the fish. Meeting with industry While the project did not involve any original research, it did provide funding for two meetings a year and an exchange of scientists between institutes. The project ended with a conference in Nantes in November 1997. "We invited representatives of the industry to come and present their views on the need for methods of evaluating fish freshness," Mrs Olafsdóttir says. "They all agreed that there was a need to have these methods in the industry. "The main conclusion is that, although sensory analysis is the method used most widely in the industry, it is not effective enough and not standardised enough. The EU scheme is not thought to be very useful; it's too broad. Since sensory analysis is mostly being used, we have to make the methods more accurate and more useful. We recommend the use of schemes like the Quality Index Method. "At the same time we realise that the industry would like to have some objective instrumental methods and there is a lot of research going on in different areas and one of them is 'electronic noses' to detect volatile compounds. We believe that such rapid techniques will be very useful for certain applications in the industry, but they have to be adapted and compared to sensory analysis to ensure they are of use to the industry. And we need to have more research on those instrumental methods that have already been developed." Rapid instrumental techniques A new FAIR project to develop a practical instrument for testing fish has already been proposed. The so-called multi-sensor for fish will combine several techniques in one instrument. "So you would actually make an instrument that could look at the different characteristics just like you do with sensory analysis, you would have an 'electronic nose' with some texture measurements, some measurement of microstructure, something like that. That's the new project idea and the future goal." Mrs Olafsdóttir believes that rapid, easy-to-use, standardised methods - either computerised QIM or rapid instrumental techniques - would play a crucial role in establishing traceability in the fish supply industry. At present, fish retailers have no means of knowing the age of the fish they sell and how fresh it really is. "At each point in the chain the fish could be checked. So the retailer could check it when it arrives from the fish market, and it would be good if the consumer could test it too." A reliable testing instrument would mean that fish could be properly labelled with expiry dates. "The consumer is putting all their faith in supermarkets, but there is no way in which the supermarket can give them any proof." Quality Labels for fish A new concerted action, "Fish Quality Labelling and Monitoring", which aims at defining quality labels for fish, has now been approved. The idea is to reach consensus on fish quality labelling and to discuss which factors (for example, freshness) affect quality. To administer such labelling schemes, good quality control and monitoring is vital, and another objective of the project is to reach agreement on appropriate, reliable, and rapid means to measure fish quality. The aim is to further develop, extend and implement the QIM as a reference method to monitor quality.     Project Title:   Evaluation of fish freshness Programmes: AIR3 Contract Reference: CT94-2283 For more information on this project, go to the Cordis database Record