HS-SPME-GC-MS Coupled with OAV to Evaluate the Aroma of Flowery Black Tea Made from Oolong Tea Varieties

To analyze the difference in aroma components and aroma characteristics of flowery black tea made from oolong tea varieties. The aroma components extracted with headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS), and odor activity value (OAV) was used to determine the key and modified flavor components. Combined with hierarchical clustering analysis (HCA), principal component analysis (PCA), orthogonal partial least squares discrimination analysis (OPLS-DA) and sensory evaluation, the aroma of flowery black tea was comprehensively evaluated. Results showed that 22 key and modified flavor components were selected from 54 identified aroma components, hierarchical clustering divided them into five categories. The models of PCA (R2X(cum)=0.892，Q2(cum)=0.645) and OPLS-DA (R2X(cum)>0.7，Q2(cum)>0.9) had a high degree of fitting. The main difference components between traditional black tea and flowery black tea were linalool, linalool oxide I, linalool oxide II and 2-methylbutyraldehyde. The main difference components between flowery black tea and oolong tea were β-cyclocitral, linalool oxide I, trans,trans-nona-2,4-dienal, hexanal, 1-penten-3-one, linalool oxide II, linalool and geraniol. Determination of flowery black tea aroma characteristics by OAV combined with chemometrics methods was consistent with the sensory results. The results of this experiment can clarify the differences in volatile substances in flowery black tea and provide for further optimization of volatile component analysis methods.