E β ocimene

The following compounds were purchased from Sigma–Aldrich (St. Louis, MO, USA): hexanal (98% chemical purity), (E)-2-hexenal (98% chemical purity), octanal (99% chemical purity), nonanal (95% chemical purity), decanal (≥98% chemical purity), (E)-2-nonenal (97% chemical purity), benzaldehyde (≥99% chemical purity), 6-methyl-5-hepten-2-one (99% chemical purity), 1-hexanol (≥99% chemical purity), (Z)-3-hexen-1-ol (98% chemical purity), 1-octen-3-ol (98% chemical purity), propyl 3-methylbutanoate (≥98% chemical purity), 3-methylbutyl propionate (≥98% chemical purity), 3-methylbutyl 3-methylbutanoate (≥98% chemical purity), hexyl acetate (99% chemical purity), ethyl octanoate (≥99% chemical purity), (Z)-3-hexenyl acetate, (Z)-3-hexenyl 3-methylbutanoate (≥97% chemical purity), α-pinene (98% chemical purity), α-phellandrene (≥95% chemical purity), limonene (≥98% chemical purity), (E)-β-ocimene (≥90% chemical purity), p-cymene (99% chemical purity), linalool (97% chemical purity), α-terpinyl acetate, 2-phenylethyl acetate (99% chemical purity), (E)-geranyl acetone (96% chemical purity), hexane (≥99% chemical purity). Ethyl hexanoate (99% chemical purity), 3-methylbutyl acetate (98% chemical purity) were purchased from Alfa Aesar (Ward Hill, MA, USA), δ-3-cerene from Carl Roth (Karlsruhe, Germany), α-farnesene from Bedoukian Research Inc. (Danbury, CT, USA).

The chemicals used for HPLC including D-(+)-xylose, 99%, D-(+)-galactose 99%, D-(-)-fructose 99%, sucrose 99.5%, maltose 99%, D-(+)-glucose 99.5%, D-(+)- trehalose 99%, D-lactose 99.5%) and acetonitrile (ACN) (HPLC grade) were purchased from Sigma-Aldrich, St. Louis, Missouri, United States. Chemicals used in the GC-MS analysis including hexanal, heptanal, benzaldehyde, octanal, nonanal, decanal, 6-methyl-5-hepten-2-one, acetophenone, α-pinene, p-cymene, sabinene, β-pinene, (E)-β-ocimene, (Z)-linalool oxide (furanoid), (Z)-linalool oxide (pyranoid), α-cedrene, octanol, 1-octen-3-ol, phytol, benzyl alcohol, m-cresol, p-cresol, indole, methyl salicylate and standard n-alkanes solution were purchased from Sigma Aldrich. All the chemicals were >97% purity.

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.

The chemicals used in GC-MS analysis including hexanal, heptanal, benzaldehyde, octanal, nonanal, decanal, 6-methyl-5-hepten-2-one, acetophenone, α-phellandrene, α-pinene, p-cymene, β-citronellene, camphene, sabinene, β-pinene, limonene, 1,8-cineole, (Z)-β-ocimene, (E)-β-ocimene, γ-terpinene, δ-2- carene, (Z)-linalool oxide (furanoid), linalool, α-copaene, α-cedrene, (E)-caryophyllene, α-humulene, (Z)- caryophyllene, skatole, heptanol, octanol, 1-octen-3-ol, nonanol, p-xylene, o-xylene, phenol, benzyl alcohol, m-cresol, p-cresol, indole, and standard n-alkanes solution were purchased from Sigma Aldrich (purity >97%).