Essential oils from citri reticulatae pericarpium: Optimization of hydrodistillation extraction and effects of stir-frying processing on chemical components and multiple biological activities

This study aims to investigate the chemical components and biological activities such as antioxidant, antibacterial, expectorant, and antitussive activities of essential oils (EOs) from raw and stir-frying Citri Reticulatae Pericarpium (ORP and OSP, respectively). The process for EOs extraction by hydrodistillation was optimized by response surface methodology. The optimized condition included soaking time of 7.20 h, liquid–solid ratio of 17.22:1, and extraction time of 4.18 h. The extraction rates of EOs from ORP and OSP were 2.11 % and 1.58 %, and 34 and 32 chemical components were identified by gas chromatography–mass spectrometry (GC-MS) with the highest proportion of monoterpene hydrocarbons (83.61 % and 93.64 %), respectively. The main components of ORP and OSP were limonene (69.43 % and 75.04 %) and γ-terpinene (8.93 % and 9.94 %). In the antitussive and expectorant tests, OSP significantly promoted tracheal secretion and inhibited cough. The cough frequency of OSP at low dose (100 mg/kg) was lower than that of theobromine. The phenol red secretion and cough incubation period of OSP at a high dose (400 mg/kg) was close to that of the positive control theobromine and ambroxol. ORP and OSP demonstrated strong antitussive and expectorant activities and also possessed certain antioxidant and antibacterial activities. These activities of OSP were significantly better than those of ORP. Hence, OSP shows great application potential in food, medicine, and chemical industries. The traditional processing technology plays a very important role in improving activities.