The Effects of Temperature and Pressure on the Characteristics of the Extracts from High-Pressure CO 2 Extraction of Majorana hortensis Moench MARIA REGINA A. RODRIGUES, ² ELINA B. CARAMA ˜ O,* ,‡ JONATHAN G. DOS SANTOS, § CLA Ä UDIO DARIVA, § AND J. VLADIMIR OLIVEIRA § Institute of Chemistry and Geosciences, Federal University of Pelotas, Pelotas, RS, Brazil, Institute of Chemistry, Federal University of Rio Grande do Sul, Av. Bento Gonc ¸ alves, 9500. CEP 91501-960 Porto Alegre, RS, Brazil, and Department of Food Engineering, URI - Campus de Erechim, Erechim, RS, Brazil The aim of this work is to assess the influence of temperature and pressure (solvent density) on the characteristics of the essential oil obtained from high-pressure carbon dioxide extraction of marjoram (commercial marjoram samples available in the free market and Majorana hortensis Moench, cultivated in South Brazil under rigorous agronomic conditions). The extracts were analyzed in terms of the liquid yield (extract/raw material, wt/wt) and distribution of volatile chemical components. The experiments were performed in a laboratory-scale unit using the dynamic method in the temperature range of 293.15-313.15 K, from 100 to 200 bar in pressure. Chemical analyses were carried out in a GC/MSD. Results show that an increase in temperature leads to a rise in the extract liquid yield despite large changes in solvent density. Chromatographic analyses permitted the identification of cis-sabinene hydrate, terpineol-4, R-terpineol, and cis-sabinene hydrate acetate as the main volatile compounds present in both commercial and cultivated samples. KEYWORDS: Chemical analysis; high-pressure extraction; extraction kinetics; marjoram; essential oil; GC/MSD INTRODUCTION Marjoram comprises several aromatic labiatae herbs belong- ing to different species. The best known is Origanum majorana L. (syn. Majorana hortensis Moench, M. Vulgaris Miller), native on Cyprus and South Turkey. It is also cultivated extensively as sweet marjoram, an annual herb, in several areas of Europe, North Africa, America, and Asia. The dried leaves of sweet marjoram are widely used by food industry as flavoring agents for dressings, soups, and in formulation of vermouth and bitters, among others (1-3). The essential (volatile) oil of sweet marjoram has been known since antiquity due to its biological activity, notably antibacterial, antifungal, and antioxidant prop- erties, thus making the investigation of the flavor composition of this raw-material of great interest (4, 5). Some studies have shown that the aroma composition may vary with the origin of plants and cultivating conditions (6, 7). For instance, some essential oils of marjoram have been obtained with high contents of monoterpene alcohols whereas in others phenols are the major constituents. In some oils, terpineol-4 is the major component, alone or together with other monoterpene alcohols such as cis- and trans-sabinene hydrate and R-terpineol. The essential oil is commonly defined by the method of preparation, namely, the separation of volatile substances by distillation at atmospheric pressure and elevated temperature (8). Other methods such as simultaneous steam distillation extraction (SDE) and supercriti- cal fluid extraction (SFE) can also produce high-quality essential oils from herbaceous materials (8, 9). For instance, Jime ´nez- Carmona et al. (10) have used subcritical water extraction (CSWE) to extract the essential oil from marjoram under dynamic conditions and have concluded that this method, when compared with hydrodistillation, provides a more valuable essential oil, because the oxygenated fraction content is larger than the terpenic one. Some studies concerning the application of high-pressure carbon dioxide to the extraction and fractionation of marjoram are available in the literature (9, 11). In a recent review, Reverchon (12) pointed out that SFE of flavors and fragrance from vegetable matters presented in the literature are focused mainly on the analytical aspects and thus there is a lack of a comprehensive study regarding the influence of process param- eters on SFE of essential oils. This work is aimed at investigating the influence of temper- ature and pressure (solvent density) on the characteristics of the extracts obtained from high-pressure carbon dioxide extrac- tion of two marjoram samples, a commercial and a cultivated * To whom correspondence should be addressed. Telephone: 55-51- 3316-7213. Fax: 55-51-3316 7304. E-mail: elina@vortex.ufrgs.br. ² Federal University of Pelotas. E-mail: regina24@terra.com.br. ‡ Federal University of Rio Grande do Sul. § URI - Campus de Erechim. E-mail for C.D.: cdariva@uricer.edu.br. J. Agric. Food Chem. 2003, 51, 453-456 453 10.1021/jf020708s CCC: $25.00 © 2003 American Chemical Society Published on Web 12/13/2002