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Elsholtzia winitiana var. dongvanensis Phuong is a plant contains an essential oil characterized by an important chemical transformation. Essential oils were isolated from Elsholtzia winitiana var. dongvanensis Phuong flowers and aerial parts by hydrodistillation and analyzed for chemical constituents by GC-MS. Twenty-two components accounting for 99.99% of the total oil of flowers and twenty-three components accounting for 98.72 % of the total oil of aerial parts were identified. The composition of the essential oil contains aldehyde, aromatic ketone, monoterpenoid and secquiterpenoid. Major components found in two essential oil samples were andehyde, terpenoid, ketone benzaldehyde, germacrene D, E-caryphyllene and caryophyllene oxide. Moreover, essential oil sample isolated from flowers and aerial parts of E. winitiana var. dongvannensis was dominated by the high content of rosefuran (75.67%) and rosefuran epoxide (71.33%), respectively.

Pomelo (Citrus maxima (Burm. f.) Merr). juice is known as an enriched source of antioxidants and nutrients. It is therefore necessary to develop a preservation method for freshly prepared juice. This study aims to determine the effect of the vacuum concentration process on the change in color, bioactive compounds and antioxidant activity of pomelo juice. High pressure showed negligible effects on color. However, longer heating time seemed to cause browning in juice. In comparison with the fresh sample, total color difference (TCD) value of the treated sample was 6.73 ± 0.58 after 150 min of heating at 85°C. The total polyphenol content (TPC) values in the sample also increased with longer heating time or increased pressure. The total flavonoid content (TFC) seemed to be non-responsive to changes in heating time and pressure but was closely related to total soluble solid. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) of pomelo juice are affected by heat and, to a lesser extent, by pressure. The changes caused by the application of vacuum dehydration in the juice texture resulted in a higher water loss and higher sugar content (52.92 ± 0.79 °Brix).

Zingiber officinale is a frequently used herb and food flavouring agent, commonly known as ginger. Z. officinale belongs to the Zingiberaceae family, comprising of more than 1200 species [1]. In traditional therapeutic systems, Z. officinale is known for its various medicinal properties that give rise to the ability to cure a variety of diseases. Ginger oil is a potential commodity, but the extraction of these oils takes a long time to produce good quality essential oils. Thus, optimization work is required in the extraction process. In this study, the extraction was performed with the hydro-distillation method, which has been widely used to extract essential oils from natural plant and herbs due to its feasibility and green technology The extraction was carried out over several extraction cycles from 15 minutes until the amount of essential oil recovered is almost unchanged. The maximum yield in ginger essential oil extract achieved 0.5% from 100 g starting material. This yield was obtained on optimum temperature conditions, extraction time and water to material ratio such as 204 W, 120 min, and 1:4 mL/g. The mathematical model of essential oil extraction was constructed, which is a crucial step in the industrial plant project because it helps to understand the extraction process and to achieve optimal operating conditions. The process kinetics in this study was modeled by the first and second-order kinetic models. The kinetics of the extraction of ginger essential oil by the hydrodistillation method has demonstrated that the extraction process is based on a second model as it has been done experimentally. The second order model was satisfactorily modified, with extremely high correlation coefficients (R2= 0.99355), demonstrating that the process was successfully described.