Change in translucency of squid mantle muscle upon storage

ABSTRACT:   Change in the translucency of squid mantle muscle during itsstorage at 0°C was studied by monitoring L* valueand turbidity. Two indicators showed that squid mantle muscle lostits translucency and reached maximal turbidity within 24 hof storage. Thickness of mantle muscle also increased by 15% in12 h, earlier than the loss of translucency. ATP contentdecreased with storage time and was completely lost in almost 24 h,a similar period to translucency loss, but later than rigor contraction.Development of black color on skin surface by chromatophores wasfully achieved in 24 h. It was thus concluded that ATPcontent was well correlated with a loss of translucency or increasein the turbidity of mantle muscle and development of dark coloron the surface skin of mantle.     

Thermal denaturation and autolysis profiles of myofibrillar proteins of mantle muscle of jumbo squid Docidicus gigas

ABSTRACT:    Jumbo squid was very similar to Japanese common squid in terms of myofibrillar Ca²⁺-, Mg²⁺- and K⁺(EDTA)-ATPase activities. Myofibrils of jumbo squid were significantly stabilized upon addition of Ca²⁺ and destabilized by increasing KCl concentration for heating. Incubation of muscle homogenate of jumbo squid induced a selective cleavage of myosin into two major fragments and the cleavage was inhibited by EDTA. Autolysis was prominent at and above 0.3 M NaCl where myosin filaments dissolve. The enzyme involved in the autolysis was proved to be unstable showing maximal autolysis rate at 25°C. Washing the homogenate partially reduced the autolysis activity.