Antimicrobial and antioxidant activities of the essential oil from onion (Allium cepa L.)

The aims of this study were to test the efficacy of essential oil of Allium cepa against food spoilage and food-borne pathogenic microorganisms and its antioxidant activity. The essential oil revealed an interesting antimicrobial effect against the tested microorganisms with the MIC and MBC values in the ranges of 0.18-1.80 mg/mL and 0.54-3.6 mg/mL, respectively. The antioxidant activities of the essential oil were investigated and the oil showed moderate antioxidant activities in ABTS assay (0.67 mg/mL as IC50 value), DPPH test (IC50 value = 0.63 mg/mL) and metal chelating assay (IC50 value of 0.51 mg/mL). Furthermore, the reducing power of the oil was dose dependent, and the reducing capacity of the oil was inferior to butylated hydroxytoluene, which is known to be a strong reducing agent. It was suggested that the essential oil from A. cepa may be a new potential source as natural antimicrobial and antioxidant agents applied in food systems. (C) 2012 Elsevier Ltd. All rights reserved.