Quantitative PCR method for evaluating freshness of whiting (Merlangius merlangus) and plaice (Pleuronectes platessa).

We have developed a method for rapid quantification of fish spoilage bacteria based on quantitative PCR with degenerated oligonucleotides that hybridize on the torA gene coding for trimethylamine N-oxide reductase, one of the major bacterial enzymes in fish spoilage. To show the utility of this gene, we used a regular PCR with DNA extracts from whiting (Merlangius merlangus) and plaice (Pleuronectes platessa) stored in ice. Quantitative PCR showed that the number of copies of the torA gene, i.e., the number of spoilage bacteria, increases with length of storage. This approach can therefore be used to evaluate freshness for the two fish species studied (whiting and plaice).