Investigating the interactions between selected heterocyclic flavor compounds and beef myofibrillar proteins using SPME-GC–MS, spectroscopic, and molecular docking approaches

In this study, the interactions between myofibrillar proteins (MPs) and key heterocyclic flavor compounds, 2-ethyl-6-methylpyrazine, 2-acetylpyrrole, 2-acetyl-thiazole, and 2-acetyl-2-thiazoline, in beef, were investigated using solid phase microextraction (SPME) combined with gas chromatography-mass spectrometry (GC–MS), spectroscopic, and followed by molecular docking. The GC–MS results revealed that the molecular structures of the flavor compounds strongly influenced their binding affinity with MPs. 2-Ethyl-6-methylpyrazine and 2-acetylpyrrole exhibited salting-out effects from the MPs solution, and 2-acetyl-2-thiazoline displayed a higher binding affinity with MPs compared to 2-acetyl-thiazole, indicated by the Hill binding models. Fluorescence static quenching experiments also demonstrated that 2-acetyl-2-thiazoline had a higher Stern–Volmer constant with MPs than 2-acetyl-thiazole. Circular dichroism analysis revealed that increased concentrations of flavor compounds transformed ordered structures in MPs into random coils. This suggests that high molar concentrations of 2-acetyl-thiazole and 2-acetyl-2-thiazoline induced conformational changes in MPs. In accordance with the molecular docking model, hydrogen bonds, van der Waals forces, and hydrophobic interactions were identified as the primary noncovalent interactions between MPs and 2-acetyl-thiazole and 2-acetyl-2-thiazoline. This study provides valuable insights for controlling flavor profiles of beef products.