Proteomic analysis revealed the deterioration of surimi gelling capability to fish stress during transportation

Live silver carp with various transportation durations (3 h, 6 h, 12 h and 24 h) was processed into surimi. Proteomics and other technical methods were applied to investigate the changes in protein composition and structure aiming to explore the mechanism through which transportation stress affects gelling capability of surimi. As the transportation time was prolonged from 3 to 24 h, the gel strength of surimi gel decreased by 28.97 %, and the whiteness value decreased significantly (p < 0.05). Moreover, malondialdehyde content in fish serum and surface hydrophobicity of surimi also increased significantly (p < 0.05), suggesting that oxidation induced protein unfolding. Proteomic analysis identified eleven significantly differential proteins in the samples after 24 h of transportation compared to those transported for 3 h. Notably, the expression levels of myosin heavy chain and glutathione peroxidase were significantly down-regulated. Additionally, the PI3K-Akt signaling pathway was activated. Prolonged transportation time resulted in a looser microstructure of surimi gels, increased free water content and uneven water distribution. These results indicated that the altered properties of surimi gel due to transportation stress are primarily related to oxidative stress which leads to oxidative denaturation of proteins and the degradation of myosin.