Since the industrial economic development, natural compounds have received much attention and study in recent years. Essential oils (EOs) that contain many volatile constituents and aromatic compounds have been around for a long time but are still considered today due to their natural characteristics and unique application. In this study, the leaves of Calamondin (Citrus microcarpa) shells were used to investigate the yield of essential oil extracted by the Microwave-assisted hydrodistillation (MAHD). Calamondin essential oil is determined by the microwave assisted hydrodistillation method and analyzed by GC-MS. Extraction essential oil Calamondin with MAHD in optimal conditions for 45 min, 300W capacity and 1:3 shells/water ratio. The main components of volatile compounds in Calamondin essential oils include limonene (96.039%), β-myrcene (0.953%), 1R-α-pinene (0.266%), sabinene (0.55%), 1,6-cyclodecadiene (1.611%), ϒ-eudesmol (0.207%), β-eudesmol (0.232%), α-eudesmol (0.185%). The oil produced by microwaves assisted hydrodistillation (MAHD) method was found to have higher levels of compounds and significant economic values.

In this study, the essential oils from lemon (Citrus aurantifolia) peels were extracted using hydrodistillation and microwave-assisted hydrodistillation and their volatile compositions were compared via gas chromatography-mass spectrometry (GC-MS) analysis. Microwave-assisted hydrodistillation (MHD) achieved the oil yield of 2.48% at microwave power of 470W and extraction time of 60 min. The yield obtained using conventional hydrodistillation (HD) was 2.2% at 90 min at 120 °C. GC-MS analysis revealed a total of 17 and 8 components existing in the oil samples produced by MHD and HD methods respectively. The main components shared by both samples were limonene, α-pinene, β-pinene, β-cymene, ocimene, and sabinene. Overall, these results suggest that MHD could produce lemon (Citrus aurantifolia) peels essential oil at a higher yield within a shortened period of time as compared to the traditional HD, thus it could be used as an alternative for HD to reduce costs of the extraction process.

The mandarin (Citrus reticulata Blanco) essential oil is well-known for bactericidal, antioxidant and anti-cancer properties. Thus, an effective extraction method is required to obtain high oil yield with an abundant content of bioactive compounds. In the present study, the chemical profiles of essential oils extracted from the peels of Mandarin) via hydrodistillation (HD), microwave-assisted hydrodistillation (MAHD) and microwave extraction (ME) were reported in this study. Extraction techniques were carried out at their optimal conditions and the results were compared with each other. Gas chromatography-mass spectrometry (GC-MS) was employed to perform compositional determination. A total of 5 components was determined, accounting for almost 100% of total oil content. The extraction efficiencies were 3.6%, 6.8%, and 5.5% respectively obtained from HD, MAHD and ME. The results showed that MAHD seemed to result in higher yield and essential oil with identical chemical composition and quality in comparison with those of other methods, suggesting that MAHD was a potential alternative method to HD to reduce the time and cost of the extraction process.

Vietnam is a leading producer and exporter of products harvested from plants of the family Piperaceae such as green pepper, black pepper, red pepper and white pepper. In this study, an attempt is made to examine the essential oil extraction process with the material of white pepper grown and harvested in Phu Quoc island, Vietnam. To maximize essential oil production, three factors consisting the ratio of materials and solvents, extraction time and extraction temperature were selected and optimized. The surface response methodology optimization resulted the highest yield of 3.6%, achieved at the ratio of material and water ratio of 1:20 g/g, extraction time of 96 min and at 130 ºC. A high F values, low P values (< 0.0001), the determination coefficient (R2 = 0.9993) and a non-significant lack of fit suggested a strong correlation between actual and predicted values of the responses. The essential oil obtained was determined for chemical composition by gas chromatography-mass spectrometry (GC-MS) method. The GC-MS results showed that major constituents existing in the oil sample were limonene, 3-carene, sabinene, β-pinene, α-pinene and α-phellandrene, accounting for 27.059, 23.345, 17.903, 9.996, 5.167 and 4.588%, respectively.