Matrix effects in supercritical CO₂ extraction of essential oils from plant material

• Published in: Journal of food engineering Vol. 92; no. 4; pp. 438 - 447
• Main Authors: Araus, Karina, Uquiche, Edgar, del Valle, José M
• Format: Journal Article
• Language: English
• Published: Oxford [New York, NY]: Elsevier Science Pub. Co 01-06-2009; Elsevier
• Subjects: Aroma and flavouring agent industries; Biological and medical sciences; camphor; carbon dioxide; chamomile; diffusion; diffusivity; essential oils; flowers; Food engineering; Food industries; Fundamental and applied biological sciences. Psychology; General aspects; Lavandula; leaves; mass transfer; mathematical models; Mentha pulegium; microstructure; molecular weight; oregano; particle size; plant extracts; porosity; sage; solid matrix; solids; solutes; supercritical fluid extraction; thymol; Essential oil plant; Essential oils; Materials; Matrix effect; Extraction; Essential oil; Mathematical modeling; Modeling; Supercritical CO2; Solid; Solid matrix
• ISSN: 0260-8774; 1873-5770
• DOI: 10.1016/j.jfoodeng.2008.12.016

In this work, we reviewed the effect of the solid matrix in the supercritical CO₂ (SC-CO₂) extraction of essentials oils from plant material. A diffusional model was adopted that assumed the substrate is as an homogeneous solid and the partition of essential oils between the solid substrate and the SC-CO₂ phases is constant. The model was fitted to literature data from several plant materials (relevant solute identified between parenthesis): chamomile flowers (α-bisabolol), lavender flowers (camphor), oregano bracts (thymol), pennyroyal leaves and flowers (menthol), and sage leaves (1,8-cineole). Based on values of binary diffusion coefficient of the solute in the solvent (D ₁₂) from a literature correlation, and the best-fit values of effective diffusivity of the solute in the solid matrix (D e) we estimated the value of the so-called microstructural factor (MF), which is defined as the ratio between D ₁₂ and D e which ranged from 420 for pennyroyal to 25,000 for oregano. MF encompasses several factors, mainly related with to the microstructure of the substrate, that affect the extraction rate of a solid substrate with a solvent.