Analysis of Volatile Compounds of Jasmine Scented Tea during the Orthodox Manufacturing Process Using HS-SPME/GC-MS

Volatile components of jasmine-scented tea during the orthodox manufacturing process were extracted using Headspace solid-phase microextraction (HS-SPME) and the major flavor compounds were identified by Gas chromatography-mass spectrometry/Retention indices (GC-MS/RI). The major volatile compounds extracted by SDE could also be obtained by HS-SPME, which appears more suitable for extraction of aromatic compounds, for its advantages of simplicity and convenience. The GC-MS chromatograms of tea samples showed that the aromatic constituents of jasmine tea had been identified in composition after 1st scenting, which contained 6 apparently high peaks representing linalool, benzyl acetate, α-farnesene, (Z)-3-hexenyl benzoate, methyl anthranilate, and indole. According to the change of peak area of major volatile compounds, (Z)-3-hexenyl acetate and (Z)-3-hexenyl butyrate with green grass aroma reduced by 71.13% and 63.10% respectively in jasmine tea product, while 7 compounds with favorable flowery fruity aroma-benzyl acetate, (Z)-3-hexenyl benzoate, linalool, benzyl alcohol, α-farnesene, methyl anthranilate and indole- increased by 17.84%, 28.33 times, 32.49%, 1.70 times, 6.67 times, 11.84 times and 21.48 times respectively, comparing to the base tea. Besides, nerolidol (fruity-flowery) and germacrene D (woody), not detected in the base tea also gradually increased. The quality grade of jasmine tea was potentially correlated to the ratio of peak area of the 9 favorable compounds to that of the 2 grass compounds. After 1st scenting, the peak areas of compounds from jasmine flower increased by 1.81×105-18.24×105, and decreased by 36.14%-69.95% after the 1st drying. The peak areas of some components detected in both the base tea and jasmine flowers, like (Z)-3-hexenyl acetate and methyl salicylate, increased by 9.05%-57.60% of those of the base tea after 1st scenting, and lost more than 100% after the 1st drying, while the increased peak areas of some other components both detected, like α-farnesene and indole, were more than peak areas of the base tea, with 30%- 95% loss after the 1st drying. The content change tendency of volatiles during 2nd scenting and the 2nd drying were consistent with those during 1st scenting and the 1st drying. After raising fragrance, the contents of some low boiling point volatiles and compounds not detected in the base tea increased.