Supercritical Carbon Dioxide Extraction of Rosemary Comparison with Steam Distillation and Hydrodistillation

Content Provider	Semantic Scholar
Author	Bensebia, Ouahida Barth, Danielle Dahmani, Amine M.
Copyright Year	2005
Abstract	Supercritical fluid extraction (SFE), steam distillation and hydrodistillation were used to extract the essential oils from rosemary (Rosemarinus officinalis) and a comparative study of extracts obtained using SFE, SD and HD is presented. Supercritical fluid extraction of natural products show that many factors have impacts on the oil yield, such as extraction pressure, temperature, particle size, addition of cosolvent and the distribution of material in the extractor. For the extraction process (SFE) of rosemary the conditions were as follows: extraction pressure of 80 100 bar extraction temperature of 3540°C dP > 0.270 mm ethanol was added directly to the material (3% mass) the raw material is charged with a packing into the extraction vessel. Under such a condition the yield obtained by SFE is higher compared to the others methods. GC analysis shows that the extracts obtained using the three methods were no similar in composition. INTRODUCTION In recent years supercritical fluid extraction (SFE) has become an alternative to more conventional extraction procedures, chiefly because the dissolving power of supercritical fluids can be adjusted by regulation the pressure and the temperature conditions employed. By using SCCO2 instead of steam distillation or extraction with organic solvent, contributes to solve the problem of toxic residual solvent in the products, and allows to use lower temperatures leading to lesser deterioration of the thermally labile components in the extract [1, 2]. Rosemary occupies 100.000 hectares of the Algerian territory [3], it is an aromatic plant used in flavouring of food, cosmetic and folk medicine, the composition of rosemary (Rosmarinus officinalis) extracts vary due to climate factors during cultivation, humidity and extraction process, there are three principal chemotypes of Rosmarinus officinalis : cineole, camphor/borneol, verbenone. Arthur et al [4] used 23 cultivars of rosemary and they observed that all cultivars could be grouped into six chemotypes based upon the composition of their essential oils, Boelens [5] concluded that two types of Rosemary oils existed one high in 1,8 cineole (from France, Greece, Tunisia and parts of Italy) and one low in 1,8 cineole (from Spain, Yugoslavia and other parts of Italy). Few studies concerning the rosemary from Algeria have been reported, Boutekedjiret et al [6] observed that the Rosemary of east Algeria origin content 30-50 percents of 1,8 cineole, our experiments showed the existence of an other chemotype: camphor/borneol. Several authors have compared the essential oil obtained by steam distillation and the product obtained by SFE, they found that steam distillation oil contained higher percentages of terpene hydrocarbons. In contrast, the SFE oil contained a higher percentage of oxygened compounds [7, 8, 9]. In the present study SFE was used to extract the essential oil from Rosemary leaves. Extraction conditions were adjusted to obtain the highest yield. Extracts were analyzed by GC and compared with Rosemary oil isolated by steam distillation (SD) and hydrodistillation (HD). 1MATERIALS AND METHODS 1-1 Materials Rosemary leaves (Rosmarinus officinalis) were collected from plants growing in university garden, the leaves were air dried. 1-2 Extraction procedures The supercritical extraction apparatus mainly consisted of a 125 ml extractor (inside diameter 23mm and length of 300mm) and three separation vessels, operated in series. CO2 (99.8 % pure, Carboxyque française, France) circulation was assured by volume metering pump (Dosapro Milton Roy. Milroyal D ) assuming a liquid flow rate up 3.2 kg/h and pressure up to 250 bar. A schematic representation of the apparatus is given in figure 1. Figure 1 : Experimental Apparatus For some experiments the extraction cell was filled with 10g of ground Rosemary (dried) and 60g of glass bead, in the extraction with ethanol as modifier, 3 % of ethanol was added directly to the material. The analysis of particle size distribution was performed by passing the ground plant material through sieves of various mesh size and weighing the fraction taken from each tray. Steam distillation and hydrodistillation were performed for 3h with a conventional apparatus, all experiments were realized with 10 g; of fresh Rosemary. 1-3 Analysis Chemical composition of extracts was determinate by gas chromatography method using a fused silica capillary column with a bonded stationary phase CP Sil 5CB, and flame ionisation detector. The identification was performed by comparison the retention time of the available pure products with the retention time of the extracted Rosemary oil. RESULTS AND DISCUSSION The raw material and drying process applied to the Rosemary plants were based on previous data obtained in our laboratory. The supercritical fluid extraction conditions were investigated in the range P = 80-100 bar and T = 35 – 40C; they were found to be optimum at P = 100 bar and T = 40C. The separators conditions were kept constant for all experiments : P1 = 80 bar, P2 = 40 bar, P3 ∼ P atm., T1 = T2 = T3 = 22°C. CO2 flow rate is kept constant near 1. g/min. The effect of following process parameters on the percentage yield were studies: particle size, packed cell, and addition of co-solvent in material leaves. All the results are summarised on table 1. Table 1: Parameters and experimental results of SFE at p = 100 bar and T = 40C Experiments Particle size (mm) Mass feed (g.) Glass bead ( g ) Ethanol ( mass % ) Yield ( % ) 1 0.224 >dp>0.160 10 0 0 Trace
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