Brussels, 16 Jul 2004
A EU-funded project has developed improved monitoring techniques to measure the freshness of fish, with the aim of improving the quality of fish available to consumers.
Traditionally, the most accurate way of assessing fish quality and freshness is through a sensory panel made up of 10 people trained to monitor attributes such as appearance, smell, taste and texture. This technique is of course expensive, both in terms of training and assembling the panel.
In response, the MUSTEC project brought together a team of partners from Denmark, Germany, Iceland, Italy, Norway, Spain and the UK in order to develop automated, multi-sensor techniques for the rapid measurement of fish freshness.
'The objective of our project was to develop instruments that mimic human senses,' explained Dr Paul Nesvadba, the project coordinator and head of food physics at Robert Gordon University in Aberdeen, UK. 'We then had to develop a quality index that characterises the freshness of the fish by combining the measurements taken by the sensors.'
The three and a half year project received 730 000 euro under the FAIR programme of the EU's Fourth Framework Programme. The aim of the FAIR programme was the promotion and harmonisation of research in the primary production sectors of agriculture, horticulture, forestry, fisheries and aquaculture.
The researchers developed instruments to measure four main attributes: texture, through compression to measure elasticity and firmness; odour, through 'electronic noses' to detect volatile compounds associated with decomposition; electrical impedance, another parameter indicating spoilage; and optical analysis of the colour and appearance of the fish surface.
Texture in particular is key during the first four days of chilled storage. The research confirmed the available biochemical models of fish spoilage, with flesh stiffness decreasing due to autolytic softening during chilled storage, and increasing due to protein denaturation and cross-linking during frozen storage. These measurements were then complimented by the 'electronic noses', which were sensitive to changes in odour from the third day of storage onwards.
'Our results show that our instrumental measurements can be calibrated to be as good as those of a trained sensory panel,' continued Dr Nesvadba. 'The added benefit of the system is that measurements can be taken online and in locations that would not necessarily be accessible to the members of a sensory panel.'