Changes of Biogenic Amines in Croaker Fish (Otolithes ruber) by Different Methods of Thawing

Biogenic amines are nitrogen-based organic compounds, which are basically produced by decarboxylation of amino acids. The presence of high amounts of biogenic amines in food represents deterioration and undesirable quality of food. In this study, changes in the amount of biogenic amines produced in the muscle of the croaker (Otolithes rubber) as a chemical indicator of spoilage caused by different methods of thawing (water, air, refrigerator and microwave) were evaluated. The croaker fishes were kept in powdered ice and transported to the processing factory, where they were deep frozen at -36°C through a freezing tunnel, followed by storage in cold store at -18°C for 4 months. The experiments were conducted by application of different thawing methods of water, air, refrigerator and microwave, followed by simultaneous monitoring of changes in the biogenic amines (histamine, putrescine, tyramine and cadaverine). The results showed a significant decrease in the amount of histamine during thawing in refrigerator compared to the other methods and control (P<0.05). Also, a significant decrease was observed in the amount of putrescine produced during thawing by microwave technique compared to the other methods (P<0.05), but there were no significant differences between the amounts of tyramine and cadaverine produced by different thawing methods compared to the control treatment (P<0.05). The highest levels of histamine and putrescine were observed in thawing methods of air and refrigerator respectively. Based on the results of this study, it can be concluded that thawing by refrigerator method can be suitable technique for defrosting the frozen croaker fish.