Essential oil extraction and evaluation from the fresh Platycladus orientalis (L.) Franco seed peel waste by an environment-friendly method

In this study, the essential oil was extracted and characterized from fresh seed peel waste of Platycladus orientalis (L.) Franco by enzymatic pretreatment combined with solvent-free microwave extraction method (EP-SME) for the first time. The optimal preparation conditions were obtained by single-factor and response surface optimization. Under the optimum conditions, the essential oil yield was 1.13%, which was 24.18% higher than that by traditional steam distillation method (SD) (0.91%), and the essential oil was rich in more polyphenols and flavonoids. The results of gas chromatography-mass spectrometry showed that the essential oil from EP-SME method had the high percentage of oxygenated compound (13.38%). Compared with SD method, the content increments of the first three components were cedrol (+4.91%), 2-carene (+2.31%), caryophyllene (+0.81%), respectively. In addition, the essential oil from the EP-SFME method showed higher comprehensive antioxidant activity and stronger acetylcholinesterase inhibitory activity than those from the hydrodistillation method. The results of extraction kinetics and energy consumption showed that EP-SME method had high extraction efficiency and reached the extraction equilibrium point in a short time (50 min). Its energy consumption and gas emission were only 15.16% of SD.