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Lemongrass (Cymbopogon citratus) essential oil (raw oil) is a natural product with many biological activities and is commonly used in the food and cosmetic industries. In this study, fractions of lemongrass essential oil were segregated from raw oil by vacuum fractionation. These fractions were then examined for their constitution, antioxidant and antimicrobial activities. Gas chromatography-mass spectrometry results indicated a difference in constitution and content of compounds among the fractions and raw oil. β -myrcene was the main ingredient in two fractions, F1and F2, with content 2-4 times higher than the original content in raw oil. At the same time, F4 was the primary fraction for citral recovery, with the highest citral content of 83.53%. Fractions F3, F4, and undistilled oil (Unoil) showed better antioxidation than raw essential oil. On the other hand, the antimicrobial experiments indicated that F1, F2, and F4 had the highest activity in both cases against Staphylococcus aureus and Escherichia coli bacteria. These outcomes could increase the applicability of lemongrass essential oil in many fields, especially in medical and food applications.

Natural products have attracted attention from scientists because of their potential to replace antibiotics in the near future. Thanks to Vietnam’s richness in biodiversity, this study aimed at evaluating antibacterial activity of eleven essential oils from various plants. These essential oils were collected from various plants across Vietnam such as corn mint, clove, clove basil, eugenol, tea tree, terpinen-4-ol, kaffir lime, Mexican mint, rosemary, Homalomena occulta, and betel. By chemical reaction and fractional vacuum distillation method, eugenol and terpinen-4-ol was isolated from clove basil and tea tree oils with the content reaching up to 97.0% and 95.8%, respectively. The antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli of essential oils was determined by disk diffusion and broth dilution method. As a result, Mexican mint oil and eugenol exhibited high antibacterial properties with low MICs and MBCs (62.5 to 125 uL/L), whereas other essential oils (clove, clove basil, betel, tea tree, terpinen-4-ol) had higher MIC and MBC values ranged from 125 to 500 uL/L.

Essential oils are incredibly effective natural antimicrobials, and they have the potential for substitute synthetic antimicrobials in the food industry, but the use of essential oils is restricted by their little solubility in water. In this research, the phase inversion temperature (PIT) method was employed to produce essential oil from orange nano-emulsions. The effects of oil phase composition, surfactant, and storage condition on the formation and stability of the nano-emulsions were investigated. Study results showed that the surfactant and oil phase constitution highly influenced the thermal property of the nano-emulsions. The transparent nano-emulsions system with the least average droplet size (46.5 nm) was created in the conditions: 10 wt% tween 80, 8 wt% essential oil from orange, 2 wt% coconut oil, and distilled water. The mean droplet diameter of these nano-emulsions raised over time and depended on the composition of surfactants. The nano-emulsion systems contained 10% tween 80 gained small size and stability after 30 days of storage, while systems with 20% tween 80 showed instability, and particle size increased rapidly after 30 days of storage. These outcomes of this investigation could be useful for the fabrication and use of nano-emulsions as distribution systems in food technology.