Minced meats of bigeye tune Thunnus obesus and halibut Hippoglossus stenolepis were vacuum-packed in retortable pouches to give about 8mm in thickness and subjected to thermal processing at F values of 8, 12, and 21 at 115°C and 124°C. Sablefish Anopoploma fimbria was thermal-processed at 115°C in the same manner.
On heating at 115°C, the contents of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) decreased in both bigeye tuna and halibut meats, being accompanied with formations of lysophosphatidylcholine (LPC) and lysophosphatidylethanolamine (LPE), while the content of free fatty acid (FFA) did not increase. Lipid composition of sablefish remained almost unchanged. On heating at 124°C, however, the contents of LPC and LPE increased in bigeye tuna and halibut meats and that of FFA decreased markedly. In addition, the PC decreased in bigeye tuna and the PE in halibut meat.
On heating at 115°C and 124°C, no appreciable change occurred in fatty acid composition of total lipid, non-polar lipid, polar lipid, PC, and PE in all fish meats examined. Only FFA changed in fatty acid composition; percentage of polyenoic acid decreased with increase in Fvalue.