Frozen skipjack was thawed under various conditions and the changes in the amounts of glycolytic intermediates in the meat were examined in relation to the extent of orange discoloration.
1. The amounts of glycogen and D-glucose in the meat decreased remarkably under all the test conditions of thawing while the amount of lactic acid increased.
The amount of glucose-6-phosphate (G 6 P) in the meat was hardly changed when thawed in iced water or in still water but increased to 117-131mg/100g from 34-42mg/100g when thawed in running water or in air.
2. When thawed in running water or in air, a strongly orange discolored meat was induced on cooking, more often than when thawed in iced water or in still water. The conditions of cooking did not influence the orange discoloration.
3. When frozen skipjack prestored at -40°C was subjected to a temperature of 1-2°C for two days during the storage and finally thawed in still water, the amount of G 6 P in the meat increased to 246mg/100g from prethawing value of 122mg/100g. A strong orange discoloration was observed in all canned products prepared from the material treated in this manner.
