A thermomechanical method of heating and mixing, was developed to study directly protein denaturation and aggregation in minced fish. It is based on simultaneous and continuous measurement of torque and temperature in a meat sample mixed while being heated. The torque and temperature were continuously recorded. From curves thus obtained, thermal denaturation temperatures of minced samples from 6 marine fish species were determined. The curves showed 4-6 peaks at 32-38°C, 44-46°C, 52-56°C, and 62-75°C, presumably corresponding to denaturation of myosin, actomyosin, sarcoplasmic proteins, and actin, respectively. The temperature range of peak 1 was 4-5°C higher in fatty fish (herring, mackerel) than in lean fish (cod, blue whiting).