Table 2.
Physical-chemical properties of fennel, peppermint, pine, and thyme essential oils.
| Property | Fennel Essential Oil | Peppermint Essential Oil | Pine Essential Oil | Thyme Essential Oil |
|---|---|---|---|---|
| Relative density [g/cm3] | 0.961–0.975 | 0.900–0.916 | 0.855–0.875 | 0.915–0.935 |
| Refraction index | 1.528–1.539 | 1.457–1.467 | 1.465–1.480 | 1.490–1.505 |
| Optical rotation, [°] | 10.0–24.0 | −30–−10 | −9.0–30.0 | −21.0–+15.0 |
| Residue on evaporation, [%] | max 1.5 | max 1.5 | max 1.5 | max 1.5 |
| Solubility in: | hexane | hexane | hexane | hexane |
| Antioxidant activity (mg equivalent to Fe2SO4 × 7H2O/g for sample) |
6.09 | 6.07 | 7.09 | 6.79 |