Lemongrass essential oil has many compounds appropriate for application in foods, cosmetics, and pharmaceutical products. Of these, citral is a high-value compound of interest to industry. This work aims to evaluate the use of vacuum fractional distillation to separate lemongrass essential oil compounds, producing essential oil fractions containing high citral content. The effect of process parameters, namely vacuum pressure, type column, and energy input, on the fractionation time, content, and recovery of citral in the fractions, was investigated. The fractionation of lemongrass oils successfully provided five fractions, i.e., fraction 1 (F1), fraction 2 (F2), fraction 3 (F3), fraction 4 (F4), and fraction 5 (F5). GC-MS (Gas Chromatography-Mass Spectrometry) spectra showed that the main compound contained in F1 and F2 fractions was β-myrcene (>70%). Meanwhile, F4 and F5 were the two main fractions for citral recovery. The optimal conditions of the fractional distillation system included a column height of 400 mm, power input of 165 W, and pressure of 15 mmHg. These conditions correspond to the highest total citral content of 95%, with a recovery of 80% at the F4 and F5 fractions. Therefore, fractional vacuum distillation may be an effective method to upgrade lemongrass essential oil.

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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.

Neem (Azadirachta indica A. Juss.) oil has been widely used in pharmaceuticals and cosmetics. The oil was extracted by the hydraulic press at the pilot scale. The effect of various critical factors such as the morphology of material, moisture of the neem seed, applied pressure, a number of presses turn, pressing time on the oil yield was considered. It was found that the oil yield increased with increasing applied pressure and pressing time. The moisture content of the neem seed kernel has a great influence on the oil yield, the higher the moisture content, the harder it is to recover the oil. The highest oil yield of 378mL/kg dry seed kernel was obtained at 190 MPa, 4% moisture content for 10 minutes of pressing per turn, and 3 turns of pressing. The main ingredients in neem kernel oil were oleic acid (45.9%), stearic acid (18%), palmitic acid (16.9%), and linoleic acid (15.65%). The results obtained can be used in the production of Neem oil at an industrial scale.

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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.

The water extraction procedure (WE) was critically selected to extract (+)-catechin and (-)-epicatechin in cashew testa. The effects of different extracting factors, including multiple extraction, extracting temperature, extracting duration, and solvent-material ratio, on catechin amounts were evaluated. Under optimal conditions, a gram of water extract (WE’) contained 151.2±4.7 mg of (+)-catechin and 85.2±2.3 mg of (-)-epicatechin. These values were nearly three-folded compared to raw material, 55.0±1.4 and 31.0±0.6 mg, respectively. By using fractional extraction with ethyl acetate, the amounts of (+)-catechin and (-)-epicatechin per gram of ethyl acetate extract (WE2) in the present extracts respectively increased to 219.4±16.5 and 123.6±8.9 mg.

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.