Funding improves the quality of the fish we eat

The quality of the fish that ends up in the shops, and eventually on our dining tables, is set to improve following a three and a half year research project into the monitoring techniques available to the fish processing industry.

The MUSTEC project, for the development of multi-sensor techniques for monitoring the quality of fish, received a grant of €730,000 from the Information Society Technology (IST) Programme of the European Union’s Framework Programme towards the overall cost of just over €1 million.

“Freshness is the most important attribute of the quality of fish” says Dr Paul Nesvadba, head of Food Physics at the Robert Gordon University in Aberdeen who co-ordinated the project. “Freshness is a complex concept, but can be estimated by a combination of several sensory attributes such as appearance, smell, texture and of course taste. Until now, the most accurate way we have had to monitor the freshness of fish was a trained sensory panel made up of 10 people who have to be specially trained. This can be expensive as the training is critical and all members of the panel are not always accessible.

“The objective of our project was to develop instruments that mimic human senses to take rapid measurements of freshness with results that are as good as those of real people on a trained sensory panel. We then had to develop a quality index that characterises the freshness of the fish by combining the measurements taken by the sensors. Our results show that our instrumental measurements can be calibrated to be as good as those of a trained sensory panel.

“The added benefit of the system is that measurements can be taken on-line and in locations that would not necessarily be accessible to the members of a sensory panel”

Peter Walters, UK National Contact Point for IST within the EU’s 6th Framework Programme, recognises the contribution EU funding had in taking the MUSTEC project forward: “Over seventy per cent of the funding for this project came from the EU’s Fifth Framework programme, so it seems fair to assume that, without it this project may well not have gone ahead. Yet the results of the project will benefit all of us who eat fish as well as the thousands of people who work in the fish processing industry.”

“The Framework Programmes are the EU’s main vehicle for support of leading edge, internationally collaborative R&D. The current Framework Programme (FP6) runs until 2006 and organisations wanting free information on how to access some of the €17.5bn available should log on to http://fp6uk.ost.gov.uk or call central telephone support on 0870 600 6080.”

Partners from seven different countries - the United Kingdom, Iceland, Norway, Spain, Germany, Italy and Denmark - carried out the MUSTEC project. They used instruments to take readings in four main areas and these readings were then combined to give an overall measurement of the freshness of the fish. The four areas were:

Texture - where instruments compress the body of the fish to measure its firmness and elasticity. This varies over a number of days in chilled storage and over several months in frozen storage.

The results show that the absolute value of the stiffness modulus of the fish flesh, although subject to biological variation, generally decreases during chilled storage and increases during frozen storage. This is in agreement with the biochemical models of fish spoilage - autolytic softening during chilled storage and protein denaturation and cross-linking during frozen storage. The texture measurements are particularly sensitive to changes during the first four days of chilled storage, thereby complementing the electronic noses that are sensitive from day 3 onwards.

Volatile compounds - using ‘electronic’ noses based on conductance changes in polymer layers and adsorption on metal porphyrrins to monitor odour, strongly associated with fish freshness. Good correlation was obtained with the sensory odour score and contributed to the construction of the Artificial Quality Index.

Electrical impedance – using commercial instruments already available to measure the disruption of fish muscle by autolytic spoilage.

Optical methods (colour, spectral and image analyses) – monitoring the colour and visible transmission spectra that change during storage. The appearance of the skin and the coarseness of protein fibres on the cut surface of fish fillets also indicate freshness.

The results of the project are of great value as a basis for designing objective multi-sensor instruments for evaluating fish freshness.