Four extraction methods of peppermint essential oil
There are four extraction methods for peppermint oil:
- Steam distillation extraction method: take 200g of crushed peppermint, put it in a volatile oil extractor, add 1000ml of water, and extract the volatile oil according to the method of determination of volatile oil in appendix XD of “Chinese Pharmacopoeia” 2000 edition. After extracting for 6 hours, the peppermint oil was collected, dehydrated with anhydrous sodium sulfate, and filtered with filter paper.
- Cold soaking extraction method: Take 20g of mint powder, soak it with 600ml of petroleum ether at room temperature for 3 times, use 200ml of solvent each time, soaking time is 3h/time, combine the extracts, evaporate the filtrate on a rotary evaporator to remove the petroleum ether, as follows The steps are the same as method one.
- Ultrasonic extraction method: take 20g of peppermint powder, use 200ml of petroleum ether as solvent, and ultrasonically extract 3 times. The ultrasonic frequency is 40kHz, and the extraction time is 30min/time. The extracts were combined, and the filtrate was evaporated on a rotary evaporator to remove petroleum ether, and the following steps were performed in the same way as method 1.
- Supercritical CO2 extraction method: take 1.3kg of peppermint powder and put it into an extraction kettle. Under the conditions of extraction pressure of 9MPa, emerald zone temperature of 50°C and CO2 flow rate of 25L/h, extract for 1.5h, collect peppermint oil, and operate in the same way as method 1 for the next step.
CO2 extraction VS steam distillation
Peppermint oil was extracted respectively according to the above method, and the oil yield was calculated. The extraction rate of steam distillation extraction method was 1.15%, the extraction rate of cold soaking extraction method was 1.27%, the extraction rate of ultrasonic extraction method was 1.34%, and the extraction rate of supercritical CO2 extraction method was 2.43%. Therefore, the supercritical CO2 extraction method and steam distillation method are commonly used in the market at present, and we will briefly introduce them below.
- CO2 Extraction Process: supercritical CO2 extraction peppermint oil machine is 1L, mint is crushed to 20 mesh, extraction pressure is 15MPa, extraction temperature is 50℃, the CO2 flow rate is 40L/H, separation pressure is 6MPa, and separation temperature 50℃, extraction time is 90min. The extraction rate under this process condition is 3.2%;
- Steam distillation: Weigh 200g of mint that has been dried and crushed through a 20 mesh sieve, add 1200mL of water, soak for 60min, distill for 3h, collect the volatile oil, dehydrate it with anhydrous sodium sulfate, and weigh it. The calculated yield is 0.84%. The volatile oil is brown. Liquid with a special fragrance.
The ABTS and FRAP methods were used to detect the antioxidant capacity of peppermint supercritical extract, and compared with the antioxidant capacity of peppermint volatile oil extracted by steam distillation. The results showed that the antioxidant capacity of peppermint volatile oil extracted by the supercritical CO2 extraction method