Identification of characteristic aroma compounds of Longjing tea and their molecular mechanisms of interaction with olfactory receptors using molecular docking

The aromas of Longjing tea samples (Qiantang, Yuezhou, and Shifeng) of different grades and origins were comparatively analyzed by gas chromatography–mass spectrometry–olfactometry (GC–MS–O) using stir bar sorptive extraction combined with thin film-microextraction (SBSE-TF-SPME). Key aroma compounds in Longjing tea were identified, including (Z)-jasmone, geraniol, 2-methylbutanal, 2-methylpropanal, 3-methylbutanal, dimethyl sulfide, dimethyl sulfoxide, etc. Furthermore, molecular docking was used to reveal the active region and active site of olfactory receptors (OR1A1, OR1D2, OR1G1, OR2W1 and OR52D1), and clarify the interactions of hydrogen bond, hydrophobic force with characteristic aroma compounds (geraniol, 2-methylbutanal, dimethyl sulfide, 3-methyl-2,4-nonanedione, and 1-octen-3-ol) of Longjing tea. The average binding energy of geraniol, 3-methyl-2,4-nonanedione, 1-octen-3-ol, dimethyl sulfide, and 3-methylbutanal on the five receptors was – 4.53 kcal/mol, – 4.21 kcal/mol, – 3.36 kcal/mol, – 2.27 kcal/mol, and – 3.43 kcal/mol, respectively. The Tyr178/Tyr276 (OR1A1), Asn109 (OR1D2), His56 (OR1G1), Lys186 (OR2W1) are key amino acid residues in the interactions. The presence of hydrogen bonding and hydrophobic interactions are important drivers of the formation of characteristic aroma compounds. The results are helpful to reveal the reasons behind the formation of characteristic aroma of Longjing tea, and provide a theoretical basis for the regulation of Longjing tea’s characteristic flavor.