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- Title
Conveyor-belt drying of Eugenia uniflora L. leaves: Influence of drying conditions on the yield, composition, antioxidant activity and total phenolic content of supercritical CO<sub>2</sub> extracts.
- Authors
Canabarroa, Nicholas I.; Ugaldeb, Gustauo A.; Mazuttic, Marcio A.; Ferreira, Maria do Carmo
- Abstract
Eugenia uniflora L. leaves were dried in a conveyor-belt dryer to assess the influence of drying conditions (air temperature and number of passes/residence time in the dryer) on the yield, composition, antioxidant activity and concentration of phenolic compounds found in the extracts obtained from supercritical extraction. An analysis of leaf drying in the conveyor belt was carried out by investigation of sorption isotherms and drying curves obtained under air temperatures of 50, 60 and 70 °C. The sorption curves were fitted to the GAB thermodynamic model and the drying curves to a one-parameter empirical equation. The fitted equations were effective to predict the discharge moisture as function of the residence time under different temperatures. The samples for extraction were dried under 50°C/120min, 60 °C/60 min and 70 °C/60 min and their moisture levels were reduced respectively to 15 wt.%, 10wt.% and 6 wt.%. The extractions were carried out at 80 °C and 250 bar using as solvents either the pure supercritical CO2 or a mixture of ethanol and supercritical CO2 at a mass ratio of 0.5:1. The higher extraction yields (9.9 ± 0.1 wt.%), phenolic content (85 ± 2 mg GAE/g extract) were found in the extracts from samples dried under 60 °C/60 min using ethanol as a co-solvent in extraction.
- Subjects
SUPERCRITICAL fluid extraction; PLANT phenols; DRYING
- Publication
Food & Bioproducts Processing: Transactions of the Institution of Chemical Engineers Part C, 2019, Vol 116, p140
- ISSN
0960-3085
- Publication type
Article
- DOI
10.1016/j.fbp.2019.05.005