Characterization of honey-like characteristic aroma compounds in Zunyi black tea and their molecular mechanisms of interaction with olfactory receptors using molecular docking

The important characteristics of honey-like aroma compounds in six Zunyi black tea were determined by gas chromatography-mass spectrometry-olfactometry (GC-MS-O), odor activity value (OAV), gas chromatographyion mobility spectrometry (GC-IMS) and partial least squares-discriminant analysis (PLS-DA) methods, including geraniol, 2-phenylethyl alcohol, 2-phenyl-2-butenal, furaneol, cinnamaldehyde, ethyl cinnamate, benzoic acid, ethyl pentanoate-M. Furthermore, the molecular docking was used to study the region, site, binding energy, and force of the interaction between the honey-like aroma compounds (geraniol, 2-phenylethyl alcohol, furanol, cinnamaldehyde, and ethyl cinnamate) and olfactory receptors (OR1A1, OR1G1, OR2W1, OR1D2, and OR5M3). The average binding energies of these compounds on the five receptors were -4.34 kcal/mol, -4.14 kcal/mol, -4.24 kcal/mol, -5.08 kcal/mol, and -5.33 kcal/mol, respectively. The experiment indicated the interaction sites of five characteristic compounds and key residues of ORs, such as geraniol and Tyr252 (OR1D2), 2-phenylethyl alcohol and Thr219 (OR1G1), furaneol and Asn155/Ser109 (OR2W1), furaneol and Phe166/ Leu164/Val7 (OR5M3), and ethyl cinnamate and Asn155/Asn109 (OR1A1). Further research has found that hydrogen bonding and hydrophobic interactions are important driving forces for the binding of aroma compounds to ORs. By systematically studying the material basis, formation mechanism of honey-like aroma, theoretical guidance can be provided for the regulation of honey-like aroma in Zunyi black tea.