Differential sensitivity of myofibrillar proteins from Litopenaeus vannamei and Parapenaeopsis hardwickii to long-term frozen storage and freeze-thaw cycles: structural destabilization and functional deterioration mechanisms

Freeze-thaw cycles amplify species-specific stability differences of shrimp MPs. • Parapenaeopsis hardwickii MPs: compact native state but high freeze-induced damage. • Litopenaeus vannamei MPs maintain superior structural integrity under frozen stress. • Results highlight the necessity of stable frozen environments for shrimp preservation. This study compared the structural and functional responses of myofibrillar proteins (MPs) from Litopenaeus vannamei (LV, farmed species) and Parapenaeopsis hardwickii (PW, wild species) to long-term frozen storage (−20 °C, FG) and freeze-thaw cycles (FC), aiming to reveal species-specific freezing sensitivity mechanisms and guide differentiated preservation strategies. Results indicated that FC induced more severe damage than FG, leading to greater oxidation (PW: hydrophobicity +29.12%, carbonyl +2.53 nmol/mg), structural unfolding (LV: α -helix −4.96/−5.21%, β -sheet +2.82/+6.93% in FG/FC; PW: α -helix −7.10/−8.17%, β -sheet +8.15/+9.27%), aggregation, and loss of solubility and emulsifying functionality. PW MPs demonstrated higher freezing sensitivity compared to LV MPs, characterized by less stable secondary/tertiary structures, faster oxidation and aggregation, and consequently a more pronounced decline in functional properties. These findings not only clarify the molecular damage pathways of shrimp MPs under frozen stress but also provide actionable guidance for industrial preservation, facilitating the quality maintenance of different shrimp products. Download: Download high-res image (253KB) Download: Download full-size image