スケトウダラおよびティラピアの肉のりのすわり中に起る筋原繊維たんぱく質の変化

Abstract

Salted meat pastes from Alaska pollack and tilapia were cooked in a water-bath at 35°C to induce the setting. During the setting, the jelly strength of the paste and several properties of myofibrils prepared from the paste were investigated with a lapse of cooking time. The gelation of Alaska pollack meat paste proceeded more rapidly than that of tilapia meat paste; the maximal jelly strength was obtained at about 2h-setting for Alaska pollack and at 10h-setting for tilapia, respectively. Solubility of myofibrils in 0.5M KCl, viscosity of the soluble protein, and myofibrillar ATPase activity were all decreased as the jelly strength of the source paste was increased; when the jelly strength was reduced to about 40% of the maximum, a bulk (80-90%) of the original biochemical properties was lost for both fish species. Microscopic observation of the myofibrils revealed that the meat paste was coagulated with the size growing larger as the setting proceeded. In addition, SDS-polyacrylamide gel electro-phoresis showed that myosin heavy chain in the meat paste gradually disappeared as the setting time prolonged. These results indicated that heat-induced gelation of the salted meat paste was caused by the denaturation of myofibrillar protein in it. It was further suggested that the above changes oc-curred more rapidly for cold-water fishes than tropical-water fishes.