Effect of different precooling methods on the physicochemical changes, water migration and myofibrillar protein characteristics of pufferfish (Takifugu obscurus) during cold storage

The objective of this study was to evaluate the effect of slurry ice (SI) in physicochemical changes, water migration, myofibrillar protein characterisation, and extended shelf life during cold storage of pufferfish (Takifugu obscurus). SI provided faster cooling rate, better structural stability of muscle tissue, and a significant reduction in total viable count (TVC). In addition, the use of SI treatment resulted in a considerable reduction in total volatile basic nitrogen (TVB-N) and pH. The results of the texture profile analysis (TPA) demonstrated that SI had a significant inhibitory effect on the reduction of hardness, springiness, resilience, and chewiness. In addition, SI treatment better maintained a well-structured myofibrillar protein stabilising the tertiary structure. Low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) revealed that SI treatment could retard the water migration. Furthermore, the results of confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) indicated that SI treatment of pufferfish effectively slowed down the degradation of their myofibrillar protein fraction throughout the cold storage.