Abstract

Physicochemical changes of oxeye scad (Selar boops) and shrimp scad (Alepes djedaba) whole muscles were investigated during ice storage (0°C) for 15 days. Muscle pHs of both species tended to increase throughout the storage period and shrimp scad muscle had a higher pH value at all time points (p<0.05). The decreases in Ca²⁺-ATPase activity, protein solubility and sulfhydryl group content with a concomitant increase in disulfide bond formation were found in both species when the storage time increased (p<0.05). The proteolytic degradation pattern of both species, analyzed by SDS-PAGE, revealed that myosin heavy chain (MHC) was negligibly hydrolyzed but an increased trichloroacetic acid (TCA)-soluble peptide content was markedly found throughout the storage time (p<0.05). Breaking force of kamaboko gel of surimi prepared from both species decreased as storage time progressed (p<0.05) but a marked reduction in breaking force was noticeable in shrimp scad (p<0.05). Therefore, extended storage in ice seemed to have a negative effect on the stability of muscle protein as well as the gel strength of surimi processed from aged fish. In addition, the physicochemical changes of fish muscle during iced storage were species-dependent.