Service Communautaire d'Information sur la Recherche et le Développement - CORDIS

Toughening in frozen fish

The project investigates the biochemical changes and mechanisms causing the aggregation of proteins in frozen fish in order to predict and control quality in terms of texture, nutrition and safety. This involves studying the interaction of myofibrillar and collagen fish proteins with formaldehyde (produced during fish storage) and fat oxidation products using techniques such as spectroscopy, radiolabelling and microscopy with a view to inhibiting toughening of frozen fish. Cod, hake, blue whiting and haddock (a species that does not produce formaldehyde) are being tested fresh and after storage at -10 C (to accelerate changes) and -30 C (controls). Proteins have been extracted using salt, sodium dodecyl sulphate (SDS) and SDS + beta mercaptoethanol. Blue whiting was the most susceptible to denaturation as indicated by proteolysis and the development of non-sulphide covalent bonds in the aggregates.

The development of fat oxidation products (rancidity) was determined by adding aldehydes and measuring the resulting fluorescence. Fluorescence was observed after 3-5 months for cod and haddock at -10 C. It was higher for cod than for haddock, and at -10 than at -30 C. However, the development of lipid oxidation products, overall, in cod and haddock was minimal in the first five months. Fillets stored at -10 C had tougher gels than those at -30 C, and values for haddock were higher than for cod. These changes were also reflected by differential scanning calorimetry.

Reported by

UNIVERSITY OF SURREY
GU2 7XH GUILDFORD
United Kingdom
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Thèmes

Biotechnology - Food