Label-free quantification proteomics reveals potential proteins associated with the freshness status of crayfish (Procambarus clarkii) as affected by cooking.

In order to characterize the freshness status of raw material of cooked crayfish products, protein and physicochemical changes were investigated in raw and cooked crayfish from fresh-live state to the early postmortem using Label-free quantification proteomics, total volatile basic nitrogen (TVB-N) and biogenic amines (BAs) analysis. Results showed that the TVB-N and BAs contents in both raw and cooked crayfish remained low levels and no obvious changes were observed within 24 h of postmortem storage at 4 °C. Altogether, six differentially expressed proteins (DEPs) were detected in both C6/C0 and C24/C0 groups by proteomics. Furthermore, five among the six DEPs were verified both in cooked and raw crayfish samples by parallel reaction monitoring. Among the six DEPs, "Unigene990_S_0_Gene.8754" changed most significantly with the increasing of postmortem time and not obviously influenced by heating, indicating that "Unigene990_S_0_Gene.8754" may be highly associated to the freshness status of crayfish.