Determination of the heating temperature of fishery products.

The German Fish Directive prescribes that products must be heated to the core temperature of +70 degrees C to kill existing larvae of nematodes. For subsequent determination of the heating temperature samples were extracted with water. The extracts were analysed for protein content, for protein patterns obtained by isoelectric focusing and by using the coagulation test. The suitability of these methods was investigated with heated extracts, heated minced fish flesh, and smoked herring and mackerel. Smoking was performed in the kiln of the institute at controlled temperatures. Analysis of commercial samples showed that the core temperature during smoking of herring and mackerel must have been clearly below 70 degrees C in several cases.