Physical properties and conformational changes of shrimp surimi from Litopenaeus vannamei during cold gelation

Variations in the cold gelation of shrimp surimi at low temperatures significantly affect their gel properties and secondary processing. In this study, the physical properties and protein conformation of shrimp surimi at 4 °C storage were investigated for fresh shrimp (F0) and shrimp frozen for 4/8 months (F4/F8). Gel hardness and frequency tests indicated that F0 maintained a sol state, whereas F4 and F8 exhibited elastic gel characteristics, and a higher degree of crosslinking occurred in F8 during storage. Gel electrophoresis revealed that the myosin heavy chain underwent polymerization in F4 and F8 during cold storage. The Raman spectra showed that F4 and F8 exhibited lower α-helix and higher β-sheet contents after storage. The intensity of C–H bending peaks and the ratio of tyrosine doublet bands also decreased significantly in F4 and F8. The changes in the secondary and tertiary structures in F8 were more notable than those in F4. Scanning electron microscopy confirmed the formation of the most compact gel network in F8. These results helped clarify the gelation process of shrimp surimi prepared from fresh and frozen states at low temperatures and contributed to regulate the gelation properties of shrimp surimi products.