Extraction temperature 35–50 ℃, significantly lower than steam distillation (≈100 ℃), preserving volatile terpenes such as D-limonene and -myrcene, as well as natural aromas, in tangerine peel oil.
Oxygen-Free Environment: The entire system is sealed, preventing oxidation, discoloration, and hesperidin degradation, resulting in light-colored essential oils with stable refractive index.
Low latent heat of solvent vaporization, and over 60% of heat energy can be recovered through internal heat exchange; solvent consumption per ton of material is <5 kg, with a processing cost of approximately 200 RMB/t⁻¹.
Single production line capacity 50–200 t·d⁻¹, equipment investment is approximately 40% lower than supercritical CO₂, suitable for industrial scale-up.
Raw materials → Impurity removal → Coarse crushing (particle size 3–5 mm) → Vacuum feeding → Subcritical extraction tank (material-to-solvent ratio 1:1.1, static 30 min + 3–4 cycles) → Temporary storage of mixed oil → Vacuum evaporation (45 ℃, -0.07 MPa) → Solvent recovery transfer tank → Crude tangerine peel oil → Molecular distillation/thin-film evaporation dewaxing and degumming → Final product (yield 2.5–4.0%, limonene content >=65%)
Besides dried tangerine peel, the same equipment can be used to extract other spice raw materials such as Sichuan pepper, vetiver, and agarwood; the by-product defatted tangerine peel residue can be further used to extract flavonoids or to make animal feed, achieving full utilization of the fruit. With the increasing demand for natural flavorings, subcritical low-temperature extraction has become the mainstream green technology for citrus essential oils, high-end flavoring oils, and the aromatic health industry.