1Hokkaido Kushiro Fisheries Experiment Station, Kushiro, Hokkaido 085-0027, 2Research Faculty of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido 041-8611, Japan
Chum salmon and skipjack tuna meats containing skin and bone were frozen and pulverized at below −130°C and the frozen powdery fish meats thus obtained were applied to extrusion cooking. The raw materials were mixed with defatted soy protein concentrate at the mixing weight ratio of 70 : 30, adjusted their moisture to 63%, and then applied to a twin-screw extruder. The extrudates showed a strong fibrous structure along with the direction of the extrusion, when the extruder was operated at 50 rpm of the screw speed and 170°C in the final barrel. There is no difference in the proximate composition between the raw materials and the extrudates. Although taurine, methionine and histidine decreased slightly during the extrusion cooking, no significant change was observed in other amino acid contents. In addition, the extrusion cooking has no effect on the fatty acid compositions of total lipid. These results indicate that fish meat containing skin and bone at the intrinsic level would be utilized for extrusion cooking without significant loss of nutrition.