Texture maintenance and degradation mechanism of ice-stored grass carp (Ctenopharyngodon idella): A scope of intramuscular connective tissue

Although intramuscular connective tissue (IMCT) is low in fish, its impact on texture cannot be ignored due to its special location. Therefore, this study was aimed to investigate the contribution of IMCT degradation to fish softening and its mechanism induced by endogenous proteases. Results showed that IMCT honeycomb-like structure collapsed entirely on the 10th day of ice storage, along with a decrease of shear force by 36.5%. Meanwhile, IMCT and myofibrils (MF) degradation accelerated softening by 25.1% and 15.3% during 10 days of ice storage, respectively. Next, IMCT deterioration was indicated to be highly correlated with decorin degradation (0.956**), followed by elastin (0.928**) and collagen (0.904**). Ulteriorly, endogenous collagenase was shown to degrade IMCT crucial components, while endogenous cathepsins had little effect. In conclusion, this study confirmed that IMCT played an essential role in maintaining fish texture and was mainly degraded by endogenous collagenase.