Hydrophobic bonds-dominated key off-odors/silver carp myofibrillar protein interactions, and their binding characteristics at cold storage and oral temperatures

This study revealed the interaction mechanism between silver carp myofibrillar protein (MP) and key off-odors by combining fluorescence spectroscopy with molecular dynamics (MD) simulation. Spectroscopic results exhibited a dynamic quenching mechanism between MP and off-odors. Thermodynamic analysis indicated that the MP/off-odors interaction was spontaneous (ΔG° < 0) and dominated by hydrophobic interactions (ΔH° > 0, ΔS° > 0). Meanwhile, the binding affinity was in the order of nonanal (n = 1.38) > hexanal (n = 0.89) > 1-octen-3-ol (n = 0.65), which was further verified by the MD results. Among off-odors, nonanal had the highest binding energy with myosin (8105.66 kJ/mol) and formed more hydrophobic binding sites to Trp residues in myosin head (e.g., Trp820 and Trp822), thereby changing myosin conformations via both physical and chemical interactions. Additionally, higher binding energies of myosin/off-odors were observed at oral temperature (37 °C) than at cold storage temperature (4 °C), implying that less off-odors were released at 37 °C.