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  • Drying of olive (Olea europ...
    Canabarro, Nicholas I.; Mazutti, Marcio A.; do Carmo Ferreira, Maria

    Industrial crops and products, 09/2019, Volume: 136
    Journal Article

    Display omitted •Olive leaves were dried in a conveyor belt dryer aimed at supercritical extraction.•Influence of drying conditions on extraction was investigated.•Leaf temperature and output moisture were successfully predicted by a drying model.•Higher extraction yields and AA were found in samples dried at 50 °C for 300 min.•Total phenolic compounds content was enhanced in samples dried at 70 °C for 60 min. The influence of drying conditions on the composition of supercritical extracts recovered from olive leaves was investigated. Leaves were dried on a conveyor belt and the effects of air temperature and residence time on the extraction kinetics, global yield, antioxidant activity, total polyphenols content and chemical profiles of the extracts were evaluated. Inlet air temperatures of 50, 60 and 70 °C with residence times of 180, 120 and 60 min, respectively were tested. A model based on mass and energy balances with effective heat and mass transfer coefficients fitted from experimental data was used to describe the drying process. The temperature and output moisture of the leaves were well predicted by the model. The extraction kinetics was not significantly affected by the drying conditions (air temperature and residence time), but the extraction yield was enhanced for samples dried at 50 °C/180 min whereas the higher values of antioxidant activity and phenolic contents were found at 60 °C/120 min. Sovová’s model was effective in describing the supercritical extraction of olive leaves and can be used to estimate the extraction kinetics and mass transfer coefficients.