Supercritical CO2 extraction of Tetraclinis articulata: Chemical composition, antioxidant activity and mathematical modeling

Operating conditions for extraction from the leaves of Tetraclinis articulata using supercritical carbon dioxide (SCCO2) were studied to focus on the feasibility of obtaining volatile and nonvolatile fractions through the use of different extraction pressures (90, 280 and 1000 bar). In addition, influence of temperature, static pretreatment and dynamic extraction durations, particle size and CO2 flow rate were investigated. All extracts were analyzed by GC-FID/MS and their antioxidant activity was measured using ABTS(center dot+) and DPPH center dot methods. Conventional hydrodistillation (HD) was also performed for comparison. At high CO2 pressure (280 and 1000 bar), the amount of phenolics in the extracts was higher (respectively 102.03 and 267.90 GAE mg/g) than for HD and supercritical fluid extraction (SFE) at 90 bar (respectively 8.89 and 9.70 GAE mg/g). Correlatively, high antioxidant activity was found for high pressure SFE. Surprisingly, for extracts obtained by SFE at 90 bar, despite very low phenolic content, significant antioxidant activity was observed, while essential oil obtained by HD, which presented also low phenolic content, exhibited low antioxidant activity. Physical aspects were only investigated for the low pressure supercritical extraction (90 bar) process. Qualitative assessment of kinetic curves together with their modeling revealed that the extraction process was mainly limited by the thermodynamic equilibrium of easily accessible solutes but where axial dispersion was significant. From this result a simple extrapolation procedure was proposed. (C) 2013 Elsevier B.V. All rights reserved.