Impact of texturing using instant pressure drop treatment prior to solvent extraction of anthocyanins from Malaysian Roselle (Hibiscus sabdariffa)

Because of the natural structure of plants, which oppose resistance to penetration by any liquid, solvent extraction is very slow. The kinetics involves multiple serial steps and generally internal diffusion is the limiting process. To improve the technological aptitude, and intensify solvent extraction, we propose to submit plants to a treatment by thermo-mechanical Instant Controlled Pressure Drop (DIC), in order to ensure the expansion of the plant structure. In this paper, we present the results of a study concerning the effect of DIC treatment on the extraction of Roselle anthocyanins. By identifying the effect of various operative parameters, we found that an appropriate DIC treatment improved both the kinetics and yield of extraction of anthocyanins from Roselle calyces. By studying extraction kinetics, we identified and quantified the effective diffusivity, which ranged from 4.62 to 6.11 x 10(-11) m(2) s(-1) for DIC treated material compared with 4.19 x 10(-11) m(2) s(-1) for raw material. (C) 2009 Elsevier Ltd. All rights reserved.