Evaluation of mechanical-pressed essential oil from Nanfeng mandarin (Citrus reticulata Blanco cv. Kinokuni) as a food preservative based on antimicrobial and antioxidant activities

An optimum condition for extraction of essential oil from Nanfeng mandarin (Citrus reticulata Blanco cv. Kinokuni) was obtained by mechanical pressing with an aid of a three-factor, three-level rotatable experiment central composite design (CCD) based on the response surface methodology (RSM). Under the optimized condition, the actual oil yield was obtained by 0.689 ± 0.01%, which well matched the predicted value. Furthermore, sixty-four components, representing 96.34% of the total oil were identified by gas chromatography-mass spectrometry (GC/MS). The essential oil revealed broad-spectrum antimicrobial effects against the tested microorganisms with the inhibition zones and minimum inhibitory concentration (MIC) values in the ranges of 9.24-16.35 mm and 7.5-60 mg/mL, respectively. The oil also exhibited moderate antioxidant activities in the 1,1-Diphenyl-2-picrylhydrazyl (DPPH), 3-(N-morpholino) propane sulfonic acid (ABTS) as well as the reducing power assays. Meanwhile, the potential active components in the essential oil were characterized according to the subsequent evaluation of antimicrobial and antioxidant activities of seventeen constituent compounds. Results demonstrated that this essential oil has the potential to act as a plant-derived natural additive for food preservation.