resumo
The supercritical CO2 extraction of E. globulus deciduous bark was carried out at different temperatures (40-60 degrees C), pressures (100-200 bar), and ethanol contents (0.0-5.0 wt. %) to study triterpenic acids (TTAs) recovery. A factorial design of experiments and response surface methodology were implemented to analyze the influence of these variables upon extraction and perform its optimization. The best conditions were 200 bar, 40 degrees C and 5% ethanol, for which the statistically validated regression models provided: extraction yield of 1.2% (wt.), TTAs concentration of 50%, which corresponds to TTAs yield of 5.1 g/kg of bark and a recovery of 79.2% in comparison to the Soxhlet value. The trends of the free and acetylated TTAs were very different, due to their distinct CO2-philic character caused by dissimilar polarities: the acetyl derivatives approached a plateau near 200 bar and 5% ethanol, while the free TTAs extraction always increased in the range of conditions studied. (C) 2012 Elsevier B.V. All rights reserved.
palavras-chave
TRACER DIFFUSION-COEFFICIENTS; OLEANOLIC ACID; CARBON-DIOXIDE; LIPOPHILIC EXTRACTIVES; OPERATING-CONDITIONS; OUTER BARKS; L.; OIL; SOLVENTS; SYSTEMS
categoria
Chemistry; Engineering
autores
Domingues, RMA; de Melo, MMR; Oliveira, ELG; Neto, CP; Silvestre, AJD; Silva, CM
nossos autores
Armando Jorge Domingues Silvestre
Professor Catedrático
Carlos Manuel Silva
Professor associado
Carlos Pascoal Neto
Diretor do Raiz
Marcelo Morais Rodrigues de Melo
Bolseiro de pós-Doutoramentoagradecimentos
We acknowledge the 7th Framework Programme FP7/2007-2013 for funding project AFORE: Forest Biorefineries: Added-value from chemicals and polymers by new integrated separation, fractionation and upgrading technologies (CP-IP 228589-2), the BIIPP project (QREN 11551) for awarding a grant to R.M.A.D., and to CICECO (Pest-C/CTM/LA0011/2011).