Thyme polyphenols modulate myofibrillar protein-odorant interactions: Molecular mechanistic insights into mutton off-flavor release

The characteristic flavor of mutton, commonly described as "muttony" or "goaty", limits consumer acceptance and market potential. This study evaluated the effects of four thyme phenolics, including gallic acid (GA), rosmarinic acid (RA), scutellarin (SCU), and apigenin-7-O-glucuronide (A7G), on the interaction between myofibrillar protein (MP) and six key off-flavor compounds. Gas chromatography-mass spectrometry showed that all four phenolics reduced MP binding with odorants and enhanced their release, with SCU and RA showing the strongest effects. Spectroscopic analyses demonstrated that phenolics induced MP conformational changes, such as decreased α-helix and β-sheet content, reduced surface hydrophobicity, and lower sulfhydryl levels. Docking and simulation confirmed that hydrophobic interactions and hydrogen bonding dominated phenolic-MP binding, and SCU exhibited the highest binding stability among tested phenolics and was likely to competitively displace 4-methyloctanoic acid. These findings provide molecular insights into how thyme phenolics promote off-flavor release and support their application in improving mutton sensory quality.