Modeling the Sequential Extraction of Water and Oil Essential from <i>Cymbopogon Citratus</i> Acclimatized in the “Plateau des Cataractes”. Empirical Diffusion and Desorption Models

Drying and oil extraction from the same plant matrix have very often been treated as independent operations with different methodologies. The study of drying involves the numerical solution of mathematical models using regression methods and leads to adjustment parameters, often without obvious physical significance: the model parameters. Oil extraction favours empirical models constructed from simple physical representations and validated graphically, in particular by linear correlation lines. In this study, these two operations were considered as a linked pair, treated using empirical models based on the phenomenological approach to metabolite desorption and validated graphically. Such an approach, with few mathematical bases and computer inputs, corresponded to our objective: the production of essential oil from Cymbopogon citratus, on a small scale and in a rural environment. Indeed, it is mainly in rural areas that lemongrass cultivation is developing with the support of public authorities as part of the fight against poverty. Peleg's desorption model and the Avrami/Page and Fick diffusion models gave consistent results, and the parameters generated had physical significance. This study showed that drying could therefore be described by the empirical methods widely used in the literature to model the extraction of various metabolites from plant matrices.