resumo
The supercritical fluid extraction (SFE) of phenolic compounds from Eucalyptus globulus bark was carried out along with detailed analysis of the extracts for the first time. The extracts were accessed in terms of: (i) extraction yield (EY), (ii) total phenolic content by Folin-Ciocalteu method (TPC), (iii) phenolics quantified by high performance liquid chromatography (PC-HPLC), and (iv) antioxidant activity (AA). Preliminary runs were performed with pure and modified CO2, using ethanol (EtOH), ethyl acetate, and water. The CO2/EtOH mixture provided the best extraction yield, high total phenolic content and antioxidant activity. Results also demonstrated high selectivity of the CO2/EtOH mixture to the extraction of flavanones, particularly eriodictyol and naringenin; and to the O-methylated flavonol isorhamentin, also found in abundance. To analyse the influence of temperature, ethanol content and flow rate on SFE at 300 bar using CO2/EtOH, a full 2(3) design of experiments was accomplished. The most favourable conditions under the experimental range studied were found as 70 degrees C, 20% ethanol, and 10 g of CO2 min(-1), for which EY = 0.48%, TPC = 57.22 mg of gallic acid equivalents (GAE)g(-1) of extract, PC-HPLC = 119.46 mg g(-1) of extract, and AA = 49.74 mg of ascorbic acid equivalents (AAE)g(-1) of extract. (C) 2012 Elsevier B.V. All rights reserved.
palavras-chave
CARBON-DIOXIDE; ANTIOXIDANT ACTIVITY; LIQUID-CHROMATOGRAPHY; CO2 EXTRACTION; PLUS ETHANOL; GRAPE SEEDS; MIXTURES; FRACTIONATION; POLYPHENOLS; SOLUBILITY
categoria
Chemistry; Engineering
autores
Santos, SAO; Villaverde, JJ; Silva, CM; Neto, CP; Silvestre, AJD
nossos autores
Armando Jorge Domingues Silvestre
Professor Catedrático
Carlos Manuel Silva
Professor associado
Carlos Pascoal Neto
Diretor do Raiz
Sónia Andreia Oliveira Santos
Investigador Auxiliaragradecimentos
The authors wish to thank 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); Fundacao para a Ciencia e a Tecnologia for the PhD. grant of S.A.O. Santos (SFRH/BD/42021/2007), for postdoctoral grant of J.J. Villaverde (BPD/UI89/4520/2009), within the Programa Operacional Potencial Humano (POPH) of QREN, and the Associate Lab CICECO funding (Pest-C/CTM/LA0011/2011).