Chemical composition antioxidant and antimicrobial activities of essential oils extracted from citrus varieties in VietNam

Abstract

Essential oils (EOs) are complex mixtures of biologically active substances used since a long time as flavoring agents and preservatives of a number of commercial products. The important characteristics of essential oils are their antioxidant and antimicrobial potential. In the present study, Vietnamese citrus essential oils from nine varieties were extracted by two methods, cold pressing and vacuum hydro-distillation. The essential oils were characterized for their chemical compositions, antioxidant and antimicrobial activities. GC analysis of the chemical compositions of the isolated essential oils revealed the presence of nine main compounds. The total concentrations of these compounds were from 63.06% to 99.27%, including α-pinene (0.04-1.98%), sabinene (0.15-3.89%), β-pinene (0.02-

21.89%), myrcene (0.96-41.95%), α-terpinene (0.02-11.41%), limonene (40.29-

95.78%), terpinolene (0.02-0.57%), ٧-terpinene (0.01-12.14%) and linalool (0.02-

0.43%). Both cold pressed essential oils and vacuum hydro-distillated essential oils show strong antioxidant and antimicrobial activities. For antioxidant capacity, the lime showed the strongest, followed by pomelo and orange EOs. The lime also had the highest antimicrobial capacity as compared to other citrus essential oils. The minimal inhibition capacity (MIC) was a range of 0.66–42 mg/ml for lime EOs, 5.25- 42 mg/ml for orange EOs, 2.63-42 mg/ml for pomelo EOs. Although the yield of essential oils extracted by the vacuum hydro-distillation method was higher than that by the cold-pressing method, the antioxidant and antimicrobial capacities of hydro-distillated essential oils were lower than those of the cold pressed extracts for all citrus varieties. The results of this study show that the vacuum hydro-distillation method used in this study could be developed to be used in industrial application and the citrus essential oils could be widely used as flavoring and preservatives in food, cosmetic and pharmaceutical industries.