Fig. 2

Effect of repeated freeze thaw cycles on the TVB-N and TBARS values of cooked crayfish (a), Raman spectra of MPs of cooked crayfish during repeated freeze-thaw cycles (b), changes in the secondary structure of cooked crayfish after repeated freeze-thaw cycles (c), and endogenous fluorescence spectra of MPs after repeated freeze-thaw cycles (d) (CK: fresh crayfish; 0 F-T: cooked crayfish with 0 freeze-thaw cycles; 1 F-T: cooked crayfish with 1 freeze-thaw cycle; 2 F-T: cooked crayfish with 2 freeze-thaw cycles; 5 F-T: cooked crayfish with 5 freeze-thaw cycles). Different letters in the same column of the same indicator showed significant difference (p < 0.05)