Adequate pre-freezing handling slows the quality deterioration of frozen obscure pufferfish: Revealed by untargeted metabolomics

To investigate the effect of different pre-freezing handling methods on the frozen quality of farmed obscure pufferfish, live pufferfish were treated with commercial slaughter (CS), spinal cord cutting (SCC), or spinal cord cutting and precooling (SCCP) before freezing. The metabolic status was evaluated by metabolomics before freezing, and quality attributes were analyzed through the water-holding capacity and texture properties of dorsal muscle during frozen storage. The results showed that quality loss followed the order of CS > SCC > SCCP, as revealed by thawing loss, cooking loss, and springiness. A total of 654 metabolites were identified from pufferfish samples; 33 and 25 differential metabolites were screened from the SCC/CS and SCCP/CS groups, respectively. Different pre-freezing handling methods significantly affected arginine and histidine metabolism, fatty acid biosynthesis, and purine metabolism, which may inhibit protein denaturation and ice crystal growth, thereby slowing the quality degradation of frozen pufferfish.

Automated summary

The effect of different pre-freezing handling methods on the frozen quality of farmed obscure pufferfish was investigated. The results showed that spinal cord cutting and precooling method contributed to better quality retention compared to commercial slaughter method, and different handling methods significantly affected certain metabolic pathways, inhibiting protein denaturation and ice crystal growth.