Z β ocimene

Authentic standards of (E)-2-hexenal, p-xylene, α-pinene, β-pinene, trans-isolimonene, β-myrcene, 2-carene, α-phellandrene, 3-carene, α-terpinene, p-cymene, β-phellandrene, (Z)-β-ocimene, (E)-β-ocimene, γ-terpinene, terpinolene, n-nonanal, allo-ocimene, methyl salicylate, β-elemene, (Z)-jasmone, (E)-β-caryophyllene, and α-humulene (>95% purity) were purchased from Sigma-Aldrich (St. Louis, MO, United States). Dichloromethane (99.9% purity) was purchased from Merck (Germany).

Standards of geranyl pyrophosphate (GPP), farnesyl pyrophosphate (FPP), geraniol, (Z)-β-ocimene, and (E)-β-ocimene were purchased from Sigma-Aldrich (St Louis, MO, USA).

Geraniol and other volatile compounds in the samples were examined using a combination of SPME and GC/MS (Thermo Scientific TRACE 1300, ISQ 7000, MA, USA). In brief, the tea samples were ground into powder in liquid nitrogen, 0.2 g of each sample was weighed and placed into the sample vial for testing. An internal standard of two μl of ethyl caprate (1 ppm in methyl alcohol) was introduced. The samples were then incubated at 60°C for 1 hour, during which the volatiles were absorbed by the SPME process. GC column: DB-5, 60 m × 0.25 mm, film thickness 0.25 μm (J&W Scientific, USA). Pure helium was used as the carrier gas at a flow rate of 1 mL/min. The GC injector had a split ratio of 10:1. The GC oven condition: maintained at 40°C for 3 min, increased by 5°C/min to 80°C; increased to 160°C at 2°C/min; and then to 240°C at a rate of 10°C/min; held at 240°C for 5 min. Full-scan mode with an m/z range of 300–600 was applied. All compounds were identified by comparison with a mass spectrometry library (NIST) and compounds with known retention times. Geraniol, (Z)-β-ocimene, and (E)-β-ocimene (Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany) were identified using standards.