Effects of cooking and heat treatment on concentration and tissue distribution of okadaic acid and dinophysistoxin-2 in mussels (Mytilus edulis)

Using high-performance liquid chromatography with mass spectrometry, the influence of conventional steaming and another heat treatment on the level of okadaic acid and dinophysistoxin-2 in mussels (Mytilus edulis) was investigated. Concentration increases correlated with water loss during steaming, and increased distribution of okadaic acid and dinophysistoxin-2 from the digestive glands to the remainder tissues was observed as a result of the processes examined. This suggests that the analysis of whole flesh tissues, as opposed to dissected digestive glands, is more appropriate for regulatory purposes, particularly if cooked samples are being analysed.A systematic heat treatment experiment showed that while okadaic acid group toxins are stable during cooking processes, degradation does occur in mussel tissues after prolonged exposure to high temperatures.The findings of the studies reported here have importance in terms of the methodology applied in regulatory phycotoxin monitoring programmes. Therefore, options for sample pretreatment are discussed.