## 2 Results and Discussion
### Volatile Compounds in Prepared Green Teas
#### 2.1.2 Compounds Present
Jasmone has been reported in _Gyokuro_ having 4.16% of volatile compounds extracted [40]. Seven samples had 2-penten-1-ol at various concentrations ranging from 0.48 ng/kg to 1.52 ng/kg. Research [7, 8] has found _cis_-2-penten-1-ol in green tea samples and have classified it as an off-flavor. However, direct comparison of the concentrations was not possible as only peak area was reported in those studies [7, 8]. The compound has been reported at a much higher concentration of 1.35 mg/kg in green tea than in our findings [41]. This difference probably is because of the variation in sample extraction. In that study [41] the sample was prepared by solvent extraction directly from green tea whereas in our study the tea samples were brewed in water. 1-Penten-3-ol was in six samples at a level of less than 1 ng/kg. It has been described as having a powerful, grass-green and very diffusive odor but the recognition threshold for this compound was not reported [33]. It has been found that green tea samples and green teas made with leaves harvested in June, when compared to those harvested in April, had higher levels of 1-penten-3-ol [7]. In a later study it was found that steam-processed samples had twice the amount of 1-penten-3-ol compared toroast-processed samples [8]. Contrary to those reports, 1-penten-3-ol was to be prevalent in stored and/or lower quality green teas in one study [42]. In this study, steam-processed green tea samples from Japan did not contain 1-penten-3-ol, although other C5 compounds (pentanal or 2-penten-1-ol) were present. Our research did show that 1-penten-3-ol was present in various Chinese and Korean samples including Korea 3, which was made from leaves collected during the first picking in April and roast-processed. At higher levels, 1-Penten-3-ol can be considered an off-flavor because it has a pungent odor, but the amounts found in our samples were well below those levels [31]. Benzeneethanol was present in six green tea samples. Concentrations in these samples were much lower than threshold, which is 1,000 \(\mu\)g/L for orthonasal evaluation and 45 \(\mu\)g/L for retronasal evaluation [31]. The compound has been reported to have a floral rose odor [29]. Six samples had toluene, which has a sweet-grassy odor [33]. Toluene was reported by a limited number of researchers studying green tea [21, 37]. Samples in this study had a wide range of concentrations from 0.35 to 3.40 ng/kg. Six samples in the study had pentanal, which typically has a woody, vanilla-like, nutty odor [37]. Pentanal has been detected in green tea when the sample was extracted using the dynamic headspace technique but it was not detected when it was extracted by simultaneous distillation-extraction technique [35]. Because pentanal is one of the first compounds to emerge from a GC column during separation, it could be an actual aromatic in the tea or may be introduced with other compounds from the column and/or be trapped residue. Five green tea samples had 2,6-dimethyl-cyclohexanol. It was detected in green tea when the sample was extracted using a dynamic headspace technique but was not found when extracted by the simultaneous distillation-extraction technique [35]. In this study, the concentration ranged from 0.33-0.66 ng/kg, but comparison of these results with other literature reports is not possible because previous researchers only reported percentage peak areas. Threshold information also was not found for 2,6-dimethyl-cyclohexanol. Styrene and 2-Hydroxy-3-methyl benzoic acid were detected in four samples each.