Freezing is an efficient way of storing fish. Objectively though, it is very hard to determine whether a fish has been previously frozen. Following an appraisal of various methods, we selected a physical determination (torrymeter), a physiological examination (eye lens) and three enzymatic assays (a-glucosidase, b-N-acetylglucosaminidase and b-hydroxyacyl-CoA-dehydrogenase) and applied them to three species: plaice (Pleuronectes platessa), whiting (Merlangus merlangus) and mackerel (Scomber scombrus). We also compared the results obtained following slow and rapid freezing and investigated how spoilage affects the torrymeter measurements and a-glucosidase assay values. For whole fish the physical method using the torrymeter is a reliable indicator. For fish fillets we recommend the enzymatic method using the a-glucosidase assay, which should be accompanied by measurement of the freshness to avoid confusing a frozen-thawed fish and a fish in an advanced stage of spoilage. The values noted for fresh and thawed whiting and plaice indicated cut-off values of 0.15 for whiting and 0.5 for plaice, above which it can be asserted that the sample had been frozen.

Producers of processed anchovies have developed hazard analysis and critical control points (HACCP) to guarantee the quality of their products. Nonetheless there is a lack of objective data to determine products' shelf life. The quality of a product is usually established on the basis of its safety and organoleptic properties. These parameters were assessed by monitoring the profiles of volatile compounds and quantitating six biogenic amines in samples of two types of processed anchovies during their shelf life. With regard to biogenic amines, quantities were below the regulatory limits throughout shelf life, except when a temperature abuse was applied for marinated samples. Moreover, this work highlights an optimum volatile profile at 5 and 6 months of storage for salted and marinated anchovies, respectively. This is the result of a higher content of six aldehyde and nine ketone compounds, mainly from lipid oxidation.

The market for vacuum-packed pasteurized seafood products is developing rapidly. The stability and safety of pasteurized products rely on pasteurization processes and subsequent storage at refrigeration temperatures. The aim of this work was to study the heat resistance of characteristic bacterial flora responsible for spoilage in pasteurized seafood products and to determine the minimal pasteurizing value required for the destruction of nonsporeforming bacteria. The DT and z-values were determined for various bacteria selected from among the most heat-resistant bacteria isolated from seafood products (Pseudomonas paucimobilis, Pseudomonas putida, Micrococcus varians, Enterococcus faecium and Staphylococcus aureus). Thermal resistance was measured in different media (fish fillet, fish terrine and M/15 phosphate buffer). The most heat-resistant microorganism found was Pseudomonas paucimobilis: the D70 varied between 1.16 and 3.36 min, and the z-value, between 5.8 and 9.1°C, depending upon the medium. The minimal pasteurizing values required to destroy a sufficient proportion of nonsporulated bacteria were determined. In France, the pasteurizing value is designated PTZ. The reference temperature was 70°C (the official reference temperature in France). In fish, the minimal pasteurizing value, p706 = 15 min, should be applied to ensure the destruction of almost any vegetative forms of bacteria. In a fish terrine, the minimal pasteurizing value should be P709 = 30 min.