Two Extraction Methods of Essential Oils: Conventional and Non-conventional Hydrodistillation

The traditional extraction of essential oils exposes plant material to high temperatures for hours, which may lead to the production of artifacts, even originating unpleasant odors and loss of quality. In addition, this procedure is energy-consuming, which makes it an expensive method. The present work has been focused on a method that combines hydrodistillation and subsequent extraction with water vapor and volatiles of essential oil in the same apparatus, that we called non-conventional hydrodistillation (NCH). Three aromatic plants were used: Rosmarinus officinalis leaves (X-1), Lavandula angustifolia flowers (X-2), and Citrus aurantium leaves (X-3). In the processes, the operating parameters as vegetal mass moisture, total sum vegetal mass used, and water flux rate have been fixed at 17 %, 100 g, and 0.97 L/h, respectively. The extraction process was made using mixture experimental design, taking into account the plants used (one plant, binary and ternary combinations); the position of the plants in the apparatus to study essential oils' yields. The results showed that NCH of binary and ternary mixtures allows obtaining higher yields than expected with values superior to 2 % for the following combinations: X-1:X-2 (50:50), X-1:X-3 (50:50); X-1:X-2:X-3 (33:33:33) and X-1:X-2:X-3 (0.67: 0.16:0.16). The new NCH had a high kinetic coefficient k (2.98) and lower extraction time (70 min) than conventional hydrodistillation (CH), which means less energy consumption.